OSAC Technical Guidance Document 0005

Strengthening Fire and Explosion 

Investigation in the United States: 

A Strategic Vision for Moving Forward https://doi.org/10.29325/OSAC.TG.0005

Fire & Explosion Investigation Subcommittee
ii

OSAC Technical Guidance Document 0005

Strengthening Fire and Explosion 

Investigation in the United States: 

A Strategic Vision for Moving Forward

Prepared for 

The Organization of Scientific Area Committees (OSAC) for Forensic Science

Prepared by

Fire & Explosion Investigation Subcommittee

Organization of Scientific Area Committees (OSAC) for Forensic Science

April 2021
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Abstract

 Strengthening Fire and Explosion Investigation in the United States: A Strategic Vision for 

Moving Forward is a strategic plan for improvements in fire and explosion investigation as a 

forensic science discipline. The OSAC subcommittee for Fire and Explosion Investigation 

performed an in-depth examination of the past and current state of fire and explosion 

investigation and its relationship to the judicial system. The subcommittee then developed a 

comprehensive series of recommendations for how to improve the practice of fire investigation. 

The first edition of NFPA 921 was published in 1992. Much progress has been made since this 

early recognition of the need to enhance the practice of fire and explosion investigation. The 

field of fire and explosion investigation can now be said to be in its adolescence, but much work 

is required to bring it to maturity.

In terms of the impact of NFPA 921 on fire-related litigation, progress has been far more rapid in 

civil litigation than in criminal matters. Judges and lawyers need to be educated and trained on 

fire science and investigation to assure that only reliable fire investigations and analyses are 

presented to juries. 

NFPA 1033 has taken its place in defining the qualifications of fire and explosion investigators. 

The continuing development of NFPA 1033 is needed to support continuing improvements in 

fire investigation. It has become clear that the current NFPA 1033 educational requirement of a 

high school degree can no longer be accepted. The 16 knowledge areas which bear on fire and 

explosion investigation are too sophisticated for investigators to master the needed science and 

technology working simply from a high school education. Fire is a collection of complex 

physical and chemical processes that necessitates investigation by those educated in the science 

and practice of fire and explosion investigation. The day when a BS in one of the physical 

sciences, engineering, or fire and explosion investigation is the entry-level educational 

requirement needs to be realized in the coming years.

The field of fire and explosion investigation needs to move toward accreditation of all fire and 

explosion investigation units. In 2016, the OSAC Fire and Explosion Investigation 

Subcommittee proposed that NFPA develop a Standard on the Organization and Operation of 

Fire Investigation Units. That proposal was accepted, a technical committee was formed, and a 

proposed draft of the standard was submitted to NFPA (NFPA 1321). This standard should 

provide a foundation for accreditation of fire and explosion investigation units.

Fire and explosion investigation units need to implement information management practices to 

minimize bias and reduce exposure to task-irrelevant data. Also, there is a need for fire 

investigation units to fully implement the scientific method and technical review processes to 

minimize potential bias. All stakeholders need to take responsibility for requiring complete and 

comprehensive fire and explosion investigation reports.

Sustained funding for fire and explosion investigation research is needed to move the discipline 

forward. The research agenda detailed in Chapter 7 needs to be implemented. Efforts are 

required to assure that research for fire investigation is easily accessed by investigators.
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Keywords

fire, explosion, investigation, OSAC, strategic plan, vision, NFPA 921, NFPA 1033, education, 

training, research, certification, accreditation, investigation reports, minimizing bias

Authors

Craig Beyler

Philip Crombie

Chris Connealy

Mark Goodson

John Lentini

Melvin “Dixon” Robin

David Sheppard

Charles “Randy” Watson

Chad Wissinger
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Table of Contents

Acronyms / Abbreviations ix

EXECUTIVE SUMMARY xi

RECOMMENDATIONS xxv

1 INTRODUCTION 1

1-1 Introduction.................................................................................................................................................................. 1

1-2 What is Fire and Explosion Investigation?................................................................................................. 2

1-3 Challenges to the Fire and Explosion Investigation Profession..................................................... 6

2. CURRENT STRUCTURE OF THE FIRE AND EXPLOSION INVESTIGATION COMMUNITY, 

AND THE NEED FOR INTEGRATED GOVERNANCE. 12

2-1 Introduction...............................................................................................................................................................12

2-2 Oversight ....................................................................................................................................................................14

2-3 Licensing.....................................................................................................................................................................15

2-4 Research.......................................................................................................................................................................15

2-5 Governance................................................................................................................................................................16

2-6 Standards for Fire Investigators.....................................................................................................................21

2-7 Conclusions ...............................................................................................................................................................25

3. THE ADMISSION OF FIRE AND EXPLOSION INVESTIGATION EVIDENCE IN 

LITIGATION 27

3-1 Science and the Law..............................................................................................................................................27

3-2 Reports and Testimony.......................................................................................................................................30

3-3 Level of Certainty...................................................................................................................................................32

3-4 The Impact of Daubert and NFPA 921 on Fire Investigation Testimony ................................34

3-5 The Impact of NFPA 1033 on Fire Investigation Testimony ..........................................................43

3-6 Conclusion.................................................................................................................................................................45

4. THE PRINCIPLES OF SCIENCE AND INTERPRETING SCIENTIFIC DATA 48

4-1 The Scientific Method.........................................................................................................................................48

4-2 Fire Investigation – Basic Methodology....................................................................................................49

4-3 Origin Determination..........................................................................................................................................51

4-4 Cause Determination ...........................................................................................................................................54

4-5 Cause Classification..............................................................................................................................................57

4-6 Hypothesis Development..................................................................................................................................57

4-7 Reliability and Validity......................................................................................................................................58
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4-8 Uncertainty and Error ..........................................................................................................................................60

4-9 Conclusions ...............................................................................................................................................................61

5. DESCRIPTIONS OF SOME FIRE AND EXPLOSION INVESTIGATION DISCIPLINES 63

5-1 Scene Examination.................................................................................................................................................63

5-2 Documenting the Scene......................................................................................................................................66

5-3 Evidence Collection/Preservation.................................................................................................................74

5-4 Interviews...................................................................................................................................................................76

5-5 Post-Incident Investigation (Non-scene)...................................................................................................79

5-6 Presentations.............................................................................................................................................................84

5-7 Conclusions ...............................................................................................................................................................85

6. IMPROVING METHODS, PRACTICE, AND PERFORMANCE IN FIRE AND EXPLOSION

INVESTIGATION 88

6-1 Introduction...............................................................................................................................................................88

6-2 Team Approach to Fire and Explosion Investigation.........................................................................88

6-3. Mitigating Bias.......................................................................................................................................................90

6-4 Reporting Results of the Fire and Explosion Investigation............................................................95

7. RESEARCH NEEDS IN FIRE AND EXPLOSION INVESTIGATION 102

7-1 The Current State ................................................................................................................................................ 102

7-2 Establishing a Research Agenda................................................................................................................. 103

7-3 Getting Research into Practice..................................................................................................................... 112

7-4 Conclusions ............................................................................................................................................................ 114

8. STRENGTHENING OVERSIGHT OF FIRE AND EXPLOSION INVESTIGATION PRACTICES

117

8-1 Certification of the Individual..................................................................................................................... 117

8-2 Accreditation of Certification Bodies....................................................................................................... 119

8-3 Accreditation of Fire Investigation Units .............................................................................................. 120

8-4 Science Advisory Workgroup for Quality Control........................................................................... 123

8-5 Code of Ethics........................................................................................................................................................ 129

8-6 Conclusions ............................................................................................................................................................ 130

9. EDUCATION AND TRAINING IN FIRE AND EXPLOSION INVESTIGATION ........................133

9-1 Introduction............................................................................................................................................................ 133

9-2 Education and Training...................................................................................................................................134

9-3 Qualification Requirements for Fire Investigators: NFPA 1033................................................ 134
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9-4 Current Sources for Fire Investigation Training and Education...............................................137

9-5 Path to Better Education.................................................................................................................................. 140

9-6 Problems / Challenges / Proposed Solutions ....................................................................................... 141

9-7 Conclusions:........................................................................................................................................................... 143

10. CONCLUSIONS 145

 
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Acronyms / Abbreviations

A2LA - American Association for Laboratory Accreditation

AAFS – American Academy of Forensic Sciences

ACFE - Association of Certified Fraud Examiners

AFCI - Arc-Fault circuit Interrupters

ANAB - ANSI National Accreditation Board

ASTM International - formerly the American Society for Testing and Materials

ATF - Bureau of Alcohol, Tobacco, Firearms, and Explosives

BLEVE - Boiling Liquid Expanding Vapor Explosions

BS – Bachelor of Science

CALEA - Commission on Accreditation for Law Enforcement Agencies

CFE - Certified Fraud Examiner

CFEI - Certified Fire & Explosion Investigator

CFII - Certified Fire Investigation Instructor

CFITrainer -Certified Fire Investigator Trainer

CFPS - Certified Fire Protection Specialists

CFR – Code of Federal Regulations

CI - Certified Instructor

CIFI - Certified Insurance Fraud Investigator

COA - Committee on Accreditation

CPSC – Consumer Product Safety Commission

CVFI - Certified Vehicle Fire Investigator

DOJ – Department of Justice

DOT – Department of Transportation

ECT - Evidence Collection Technician

F - Fahrenheit

FIT - Fire Investigation Technician

FIU - Fire Investigation Unit

FRI - Full-Room Involvement

FRL - Fire Research Laboratory

FSAB - Forensic Specialties Accreditation Board

GC-MS - Gas Chromatography coupled with Mass Spectrometry 

GFCI - Ground-Fault Circuit Interrupters

HVAC – Heating Ventilating and Air Conditioning

IAAI - International Association of Arson Investigators

IASIU - International Association of Special Investigation Units

ICAC - Insurance Committee for Arson Control

ICS - Incident Command System

IFMA - International Fire Marshals Association

IFSAC - International Fire Service Accreditation Congress
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IGL Canines – Ignitable Liquid Detection Canine

ILR - Ignitable Liquid Residues

ISFI - International Symposium on Fire Investigation Science and Technology

ISO/IEC - International Organization for Standardization and the International 

Electrotechnical Commission

JPR - Job Performance Requirements

KSA - Knowledge, Skills, and Abilities

LEAA - Law Enforcement Assistance Administration

MS – Master of Science

NAFI - National Association of Fire Investigators

NAS – National Academy of Science

NASFM - National Association of State Fire Marshals

NASP - National Association of Subrogation Professionals

NBS - National Bureau of Standards (now named NIST)

NCFS - National Commission on Forensic Science

NFPA – National Fire Protection Association

NIJ - National Institute of Justice

NIST - National Institute of Standards and Technology

OSAC - Organization of Scientific Area Committees

OSHA – Occupational Safety and Health Administration

PI - Private-sector Fire Investigators

Pro Board - National Board on Fire Service Professional Qualifications

QA – Quality Assurance

SAW - Science Advisory Workgroup

SDS – Safety Data Sheet (formerly MSDS)

SFMO - State Fire Marshal’s Office

SFPE - Society of Fire Protection Engineers

SOP - Standard Operating Procedure

TDI - Texas Department of Insurance

TIA - Tentative Interim Amendment

TX FSC - Texas Forensic Science Commission

UL – Underwriters Laboratory

ULTR - Uniform Language for Testimony and Reports
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EXECUTIVE SUMMARY

 Strengthening Fire and Explosion Investigation in the United States: A 

Strategic Vision for Moving Forward is a strategic plan for improvements in 

fire and explosion investigation as a forensic science discipline. The OSAC 

subcommittee for Fire and Explosion Investigation performed an in-depth 

examination of the past and current state of fire and explosion 

investigation and its relationship to the judicial system. The subcommittee 

then developed a comprehensive series of recommendations for how to 

improve the practice of fire investigation. The Table of Contents of this 

document is modeled after the National Academy of Science (NAS) report 

of 2009, Strengthening Forensic Science in the United States: A Path Forward.

The executive summary provides the findings and recommendations of the 

strategic plan on a chapter-by-chapter basis. Chapter 1 is an introduction to 

the document, Chapters 2 through 5 describe the field of fire and explosion 

investigation as it is currently practiced, and Chapters 6 through 9 address 

the changes needed to move the profession forward.

While great progress has been made since the 1980s, there remains much to 

be done. This strategic plan identifies the work that is needed in the field of 

fire and explosion investigation in the coming years. The day in which 

NFPA 1033, NFPA 921, and a fire investigation unit standard (NFPA 1321)

are used in an integrated manner by certified fire and explosion 

investigators with sufficient education in the discipline, working in 

accredited fire and explosion investigation units, routinely producing highquality investigations and reports can be envisioned. It remains for the fire 

investigation community to work toward achieving that end in the coming 

years.
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Chapter 1. Introduction

The writing of this strategic plan was undertaken by the Fire and Explosion 

Investigation Subcommittee of OSAC after the subcommittee had 

completed the approval process for inclusion of NFPA 921, Guide for Fire 

and Explosion Investigations (2014), and NFPA 1033, Standard for Professional 

Qualifications for Fire Investigator (2022), on the OSAC Registry of Approved 

Standards. Subsequently, the 2017 edition of NFPA 921 replaced the 2014 

edition on the registry. The subcommittee had also prepared a proposal to

NFPA to develop a Standard for the Organization and Operation of Fire 

and Explosion Investigation Units. This proposal was accepted in 2018, and 

the committee began its work in 2019. These consensus documents fulfill 

the basic elements of the quality triangle in forensic science, with NFPA 921 

providing the standardization of procedures and practices, NFPA 1033 

providing the basis for qualifications and certification of investigators, and 

the new NFPA standard (NFPA 1321) providing the basis for accreditation 

of investigation units.

Fire investigation is the process of determining the origin, cause, and 

development of a fire or explosion. The term fire investigation is widely 

used to include explosion investigation. Fire investigations involve the 

analysis of witness and electronic data, fire damage patterns, and fire 

dynamics. The examination of physical evidence includes the fire scene 

examination, laboratory analyses of artifacts, and chemical analysis of fire 

debris. Chemical fire debris analyses are carried out by chemists, while 

artifact examination and analyses are at times carried out by engineers of 

varying disciplines, metallurgists, and chemists. 

The broader objectives of ascertaining the origin, cause, and development 

of the fire that fall to the fire investigator are typically more complex than 

laboratory sample analysis. As the fire grows and consumes combustibles, 

the complexity of the analysis of chemical and physical aspects of the fire 

increase while the artifacts that constitute evidence of the origin and cause 

of the fire continue to be consumed or altered by the fire. 

The standardization of methodology is gradually taking place as courts 

decide that NFPA 921 represents the “standard of care,” but many 
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investigators still practice without the benefit of certification. Accreditation 

of organizations is practically nonexistent in fire investigation.

Judges are called upon to be “gatekeepers” for forensic science evidence. 

Attorneys need to become better educated in science if they are to have any 

hope of presenting reliable evidence to juries. It is up to experts in fire 

investigation to pass their knowledge on to officers of the court through 

their reports and testimony. 

Chapter 2. Current Structure of the Fire and Explosion Investigation 

Community, and the Need for Integrated Governance

The fire investigation community includes both public and private sector 

investigators. Public sector fire investigators work for federal, state or local 

agencies, either law enforcement entities or fire departments. Federally, fire 

investigation is almost always carried out by the Bureau of Alcohol, 

Tobacco, Firearms, and Explosives (ATF). ATF agents are available to assist 

state and local investigators, and for significant events, ATF’s National 

Response Team can be mobilized. The primary focus of public sector 

investigators is determining if the cause of the fire or explosion was 

accidental or the result of a criminal act. Private sector investigators are 

primarily employed by fire investigative or engineering firms and 

insurance companies. Private sector fire investigators often are focused on 

fire causes that relate to product liability, insurance coverage and 

subrogation. Insurance companies have financial incentives to identify 

defective equipment or services that are responsible for the cause of the 

loss. Subrogation litigation is a major driver for the private sector fire 

investigation business.

Since the first publication of NFPA 921 in 1992, fire investigation began to 

see an increase in research through a variety of public and private efforts. 

Since the 2009 NAS Report, there has been an increase in funding of 

research in fire investigations by the National Institute of Justice (NIJ). 

Results of fire research are presented in NIJ reports, in journals, at meetings 

such as the International Association of Arson Investigators (IAAI) Annual 

Training Conference, and the International Symposium on Fire 
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Investigation Science and Technology (ISFI). It is expected that the science 

of fire investigation will be moved forward by this additional research. 

There are still many areas in fire investigation where there has been little to 

no research. Additional research is needed to validate forensic methods 

that assist with origin and cause investigations.

Fire investigators are largely governed by two professional organizations; 

the IAAI and the National Association of Fire Investigators (NAFI), based 

on NFPA consensus documents. Both of these organizations offer 

certification at different levels, and both organizations provide their 

members with publications directing them to the latest research. Each 

organization also has a Code of Ethics, to which members must subscribe.

Chapter 3. The Admission of Fire and Explosion Investigation Evidence 

in Litigation

The admission or exclusion of expert testimony is the responsibility of the 

trial court judge, the “Gatekeeper.” In the years before NFPA 921, there 

was little effective basis for gatekeeping, even if judges were scientifically 

literate.

The first edition of NFPA 921 was published just a year before the Daubert1

decision was handed down. Two important court decisions were issued in 

1998-1999. In Michigan Millers Mutual Insurance Corporation v. Benfield, the 

Eleventh Circuit ruled that the testimony of the fire science expert was 

subject to Daubert review because the testimony was based on scientific 

principles, above and beyond experience and skills.2 In Kumho Tire

Company v. Carmichael, the U.S. Supreme Court ruled that all expert 

testimony, not just “scientific” testimony, is subject to a Daubert evaluation 

1

 Daubert v. Merrell Dow Pharm., Inc., 509 U.S. 579, 597, 113 S. Ct. 2786, 2798 (1993)

2 Michigan Millers Mut. Ins. Corp. v. Benfield, 140 F.3d 915 (11th Cir. 1998) (“We do not 

hesitate in finding that Buckley's testimony was science-based, rather than experience-based, and 

as such is subject to Daubert 's inquiry regarding the reliability of such testimony.”).
xv

of its relevance and reliability.3 Thus, in federal cases, fire investigators’ 

testimony was subject to scrutiny under Daubert because Daubert inquiries 

on reliability applied to all expert testimony.4

In 2000, the IAAI endorsed the adoption of NFPA 921, and the U.S. 

Department of Justice declared that fire scene examination should be 

conducted in accordance with NFPA 921. Daubert and NFPA 921 in 

tandem moved fire investigation into the world of forensic science.5. 

NFPA 921 has become deeply entrenched in the post-Daubert world of fire 

litigation, even if courts do not always require that fire investigators 

testify that they followed it or be able to articulate why they deviated from 

its guidance.6. Although the first two decades of Daubert challenges relied 

on NFPA 921, more direct challenges of the investigator’s qualifications 

3 Kumho Tire Co. v. Carmichael, 526 U.S. 137, 119 S. Ct. 1167, 143 L. Ed. 2d 238 (1999) 

(“Daubert's ‘gatekeeping’ obligation, requiring an inquiry into both relevance and 

reliability, applies not only to ‘scientific’ testimony, but to all expert testimony”).

4 It must be remembered, however, Kumho Tire was not adopted by all state courts; thus, 

in states that have not adopted Kumho Tire, expert non-scientific testimony is not subject 

to Daubert. In those states, the relevant question is whether fire science testimony is 

scientific in nature or non-scientific. For example, in West Virginia fire science 

testimony is non-scientific and thus not subject to evaluation under Daubert. See Anstey 

v. Ballard, 237 W. Va. 411, 428, 787 S.E.2d 864, 881 (2016) (“Even today, the admissibility

of the State’s expert testimony would be assessed under Rule 702 of the West Virginia 

Rules of Evidence as evidence based on technical or specialized knowledge—and not 

under Daubert/Wilt.”).

5 Notably, in Frye jurisdictions that have not adopted Daubert, NFPA 921 alone acts to 

demand better science-based investigations.

6 See, e.g., Russell v. Whirlpool Corp., 702 F.3d 450, 455 (8th Cir. 2012) (“We have held 

NFPA 921 qualifies as a reliable method endorsed by a professional organization, but 

we have not held NFPA 921 is the only reliable way to investigate a fire. Our NFPA 921 

cases stand for the simple proposition an expert who purports to follow NFPA 921 must 

apply its contents reliably.”) (citations and internal quotation marks omitted); 

Schlesinger v. United States, 898 F.Supp.2d 489, 504 (E.D.N.Y. 2012) (“As an initial matter, 

the Court need not determine whether [the] methodology complied with NFPA 921, 

because both experts testified that they did not follow NFPA 921 in reaching their 

conclusions that the fire was incendiary.”).
xvi

based on NFPA 1033 are likely to become more common. These challenges 

should result in a more careful vetting of fire investigators proposing to 

give expert testimony, and an overall improvement in the quality of 

evidence presented to courts and juries.

Chapter 4. The Principles of Science and Interpreting Scientific Data

The core methodology for fire and explosion investigation has been the 

scientific method. Drawing on the data (case facts) and knowledge of fire 

science, the process of recognizing the need, defining the problem, 

collecting data, analyzing the data, developing hypotheses, testing these 

hypotheses, and reaching the final hypothesis is iterative, thoroughly 

documented, and transparent. The structure of the process reduces the 

potential impact of cognitive biases.

The scientific method is first applied to origin determination and then to 

cause determination. Along the way, narrower problems subsidiary to the 

origin and cause determinations are also structured and addressed through 

the scientific method. 

The origin of the fire is the location in three dimensions where the fire 

started. Initially, the origin is unknown and can be thought of as being 

indefinite in size and location. The process of hypothesis formulation and 

testing is one of paring down the volume of the origin by eliminating 

hypothesized volumes. 

The primary interest in determining the origin of the fire is in the service of 

determining the cause of the fire. The cause determination process requires 

the formulation of cause hypotheses for all potential ignition sources 

within the area of origin, as well as identifying the first material ignited, 

and the ignition sequence. The process of cause determination is simplified 

by a well-defined area of origin. However, one of the most serious errors 

an investigator can make is to over-define the area of origin, such that 

legitimate potential causes are not considered.
xvii

Both the origin and cause hypotheses need to be specific so that hypothesis 

testing is possible. The origin and cause of a fire is determined if one and 

only one origin and cause hypothesis survives hypothesis testing among all 

the hypotheses developed.

Investigative errors can arise in data collection, data analysis, development, 

and testing of hypotheses. Failure to collect sufficient data and 

misinterpretation of data can cause erroneous findings. Further, the use of 

biasing irrelevant data can lead to investigative errors. Expectation bias 

arises when premature conclusions are reached. Confirmation bias arises 

when investigators lapse into attempts to prove rather than disprove a 

hypothesis.

In the end, investigators need to be able to articulate the scientific method 

and demonstrate how it was applied to the investigation. Hypothesis 

development and testing need to be effectively communicated. Rigorous 

independent review of the investigation is needed to assure quality work 

product.

Chapter 5. Descriptions of Some Fire and Explosion Investigation 

Disciplines

The various tasks within an investigation are set forth by NFPA 1033, 

Professional Qualifications for Fire Investigator, as Job Performance 

Requirements (JPR’s):

1. Scene Examination

2. Documenting the Scene

3. Evidence Collection/Preservation

4. Interviews

5. Post-Incident Investigation (non-scene)

6. Presentations (written and oral reports, testimony)

The central focus of the scene examination is the identification of the fire 

effects and patterns of fire effects such as melting, charring, discoloration, 
xviii

etc. The identification of patterns of the fire effects provides the basis for 

hypothesis development and testing. 

In some cases, fire effects and patterns of fire effects can be identified by 

simple visual observation. In other instances, the identification of 

individual fire effects requires very close observation and may require 

measurements or analyses to identify. Visual fire effects are often a 

combination of multiple fire effects which are not easily separated through 

simple observation.

Fire scene reconstruction is an important scene examination process. The 

removal of debris and the establishment of the configuration of objects and 

fire effects upon these objects can provide significant data and better 

highlight patterns of fire effects and other contextual data. 

Documenting the scene is a central task in fire and explosion investigation, 

the goal of which is to preserve data for later analysis. Data that is 

documented include fire patterns, evidence, personnel and processes, 

structures/vehicles and their systems, and testing. Documentation is 

typically done through a combination of photography (and photo logs), 

videography, note-taking, sketching/diagramming, measurements, and 

audio recording. 

Interviews are critical in nearly all fire investigations with interviews of 

first responders, the fire discoverer(s), occupants, witnesses, property 

owners and others with information about the property and the event. 

Non-scene data is often critical to fire investigations. The non-scene data 

has a role in defining the timeline of the incident, identifying the area of 

origin, documenting the growth and spread of the fire, and in providing 

causation information. Non-scene data should be integrated with scene 

data for analysis.

The culmination of the documentation of an investigation is typically a 

written report. The report details the data collected at the scene, physical 

evidence collected, interviews, and non-scene data. The use of the data to 

develop and test hypotheses is fully described concerning both origin and 
xix

cause determinations. The process of hypothesis development and testing 

needs to be fully explained such that another investigator can evaluate the 

use of the scientific method to reach conclusions.

Chapter 6. Improving Methods, Practice, and Performance in Fire and 

Explosion Investigation

A team approach to a fire investigation is more effective than a lone 

investigator. The need for a team approach has three complementary 

aspects: 1) safety, 2) the diversity of technical skills required, and 3) the role 

of collegial interaction.

Working safely on the fire scene requires multiple people. The need for 

additional investigators grows with the size and complexity of the fire 

scene. Perhaps most importantly, working as a team in all investigations 

fosters collaborative investigative work. The collegial interaction of team 

members can act to minimize individual biases.

There is a need to consider only data that is relevant to the task to guard 

against presumptions and bias. Relevant data germane to the origin and 

cause investigation includes information about the fire scene and the 

actions that occurred at the fire scene either before or during the fire. Taskirrelevant data as it pertains to the origin and cause determinations often 

relates to motives. Financial, criminal history, social relationship stress, 

evasive, or deceptive behavior information are not relevant to the 

determination of the origin or cause of a fire.

The origin and cause analysis needs to be conducted separately from other 

aspects of the investigation, including determining whether or not a crime 

has been committed, the potential for insurance fraud, or potential civil 

litigation. It is sound practice for the fire investigator to only consider data 

needed for an origin and cause determination. Shielding the fire 

investigator or a technical reviewer from information not directly relevant 

to the origin and cause of the fire has been suggested as one way that this 

can be accomplished.
xx

Reports need to be written in such a way that the process of analyzing data 

and developing and testing hypotheses is fully explained. In this manner, 

another investigator can evaluate the use of the scientific method to reach 

particular origin and cause conclusions. The report needs to identify the 

hypotheses that survive the testing process and report the findings 

concerning the fire origin and cause.

An origin and cause report should be technically and administratively 

reviewed to ensure completeness, clarity, and technical quality. These 

reviews are a way to identify other potential hypotheses, further test 

identified hypotheses, and to identify and mitigate bias.

Chapter 7. Research Needs in Fire and Explosion Investigation

Fire investigation, like many other forensic science disciplines, suffers from 

an inadequate research base. Much of the research conducted into fire 

phenomena has developed over the last fifty years and was primarily 

aimed at understanding factors related to fuels and the development of 

fires in compartments to improve fire safety rather than being focused on 

determining the origin and cause of fires. There is a need for concerted and 

focused research programs specifically designed to address the needs of 

fire and explosion investigation.

This report has enumerated 14 Research Agenda items presented after this 

executive summary. 

Chapter 8. Strengthening Oversight of Fire and Explosion Investigation 

Practices

Forensic science practitioners, should become certified.

In addition, fire investigators need competency as well as proficiency 

testing. Competency testing demonstrates the successful completion of a 

tested training course, while proficiency testing is where the fire 

investigator’s performance is evaluated through their reports, 
xxi

trial/deposition performance, mock reliability hearings, and reviews of 

investigations by independent third parties. Though not a regular function 

within most fire investigation units, proficiency evaluation needs to be as 

common as competency testing.

There is currently no standard suitable for the organization, operation, and 

accreditation of Fire and Explosion Investigation Units. The OSAC Fire and 

Explosion Investigation Subcommittee prepared a proposal to NFPA to 

develop a standard for the organization and operation of fire and explosion 

investigation units. An NFPA committee has been developed, and 

committee work on the standard is underway. 

It is vitally important that any fire investigation agency be compliant with 

best practices. Accreditation is an important component of validating that 

an agency is assuring that their investigators meet NFPA 1033 

requirements and investigating fires according to NFPA 921. An 

accreditation process creates an environment of continuous improvement 

based on national consensus standard best practices. It is the OSAC Fire 

and Explosion Subcommittee’s vision that in time, accreditation will 

become the norm in fire investigation units. 

Innovations are needed to move forward with quality improvements. The 

Science Advisory Workgroup (SAW) as developed by the Texas State Fire 

Marshal’s Office (SFMO) is one recent innovation that represents a model 

available to other states and jurisdictions. The Texas SAW provides 

training to fire investigators and conducts retrospective case reviews to 

help the SFMO investigators become increasingly proficient. 

Chapter 9. Education and Training in Fire and Explosion Investigation

Fire investigation is a recognized forensic science discipline that requires a 

high level of procedural knowledge as well as a working understanding of 

a variety of traditional scientific and engineering subjects. A major 

challenge to educating fire investigators is that most had little or no 

scientific education before entering the field. 
xxii

The qualification requirements for fire investigators are defined in NFPA 

1033: Standard for Professional Qualifications for Fire Investigator. 

Notably, the minimum education required by NFPA 1033 is a high school 

diploma. It is generally accepted that knowledge of scientific and 

engineering concepts is necessary to produce accurate determinations of 

the origin and cause of fires. A high school diploma does not guarantee any 

significant background in science.

NFPA 1033 also requires that investigators have and maintain at a 

minimum an up-to-date basic knowledge of 16 technical topics beyond the 

high school level. The OSAC subcommittee on Fire and Explosion 

Investigations recommends that the 16 topics should be reorganized and 

the level of knowledge and proficiency that investigators need in the topic 

areas should be more precisely defined.

While many training opportunities exist for fire investigators, there are 

minimal educational programs available. Only three (3) universities in the 

United States currently provide degree programs specific to fire 

investigation.

For fire investigators to understand the scientific aspects of the profession, 

they should have a working knowledge of the following topics: 

mathematics, chemistry, heat transfer, thermodynamics, fire dynamics, and 

electrical wiring theory and practice. Ideally, this knowledge would be 

acquired through coursework at an accredited academic institution. 

Additional degree programs specific to fire investigation should be 

designed and implemented at other institutions around the United States. 

A curriculum specific to fire investigation should be integrated into closely 

related fields of study to assist with those entering the field from other 

engineering and physical science degree programs. 

Most fire investigators have limited experience testifying in court, and the 

first time that many investigators are subjected to a challenging review of 

their work is when an investigation is going to court. This has the potential 

of impacting court outcomes. Mock Daubert motions and trials should be 
xxiii

used in training programs to provide investigators the opportunity to 

better prepare for such hearings.

New training and proficiency testing programs should be implemented to 

assure that fire investigators have the skills and knowledge to come to the 

correct conclusion about the causes of fires.

Chapter 10. Conclusions 

The first edition of NFPA 921 was published in 1992. Much progress has 

been made since this early recognition of the need to enhance the practice 

of fire and explosion investigation. The field of fire and explosion 

investigation can now be said to be in its adolescence, but much work is 

required to bring it to maturity.

In terms of the impact of NFPA 921 on fire-related litigation, progress has 

been far more rapid in civil litigation than in criminal matters. Judges and 

lawyers need to be educated and trained on fire science and investigation 

to assure that only reliable fire investigations and analyses are presented to 

juries. 

NFPA 1033 has taken its place in defining the qualifications of fire and 

explosion investigators. The continuing development of NFPA 1033 is 

needed to support continuing improvements in fire investigation.

It has become clear that the current NFPA 1033 educational requirement of 

a high school degree can no longer be accepted. The 16 knowledge areas 

which bear on fire and explosion investigation are too sophisticated for 

investigators to master the needed science and technology working simply 

from a high school education. Fire is a collection of complex physical and 

chemical processes that necessitates investigation by those educated in the 

science and practice of fire and explosion investigation. The day when a BS 

in one of the physical sciences, engineering, or fire and explosion 

investigation is the entry-level educational requirement needs to be 

realized in the coming years.
xxiv

The field of fire and explosion investigation needs to move toward 

accreditation of all fire and explosion investigation units. In 2016, the 

OSAC Fire and Explosion Investigation Subcommittee proposed that 

NFPA develop a Standard on the Organization and Operation of Fire 

Investigation Units. That proposal was accepted, a technical committee was 

formed, and a proposed draft of the standard was submitted to NFPA. This 

standard should provide a foundation for accreditation of fire and 

explosion investigation units.

Fire and explosion investigation units need to implement information 

management practices to minimize bias and reduce exposure to taskirrelevant data. Also, there is a need for fire investigation units to fully 

implement the scientific method and technical review processes to 

minimize potential bias. All stakeholders need to take responsibility for 

requiring complete and comprehensive fire and explosion investigation 

reports.

Sustained funding for fire and explosion investigation research is needed to 

move the discipline forward. The research agenda detailed in Chapter 7 

needs to be implemented. Efforts are required to assure that research for 

fire investigation is easily accessed by investigators.
xxv

 RECOMMENDATIONS

The following recommendations will require advocacy from all fire and 

explosion investigation stakeholders. The identified stakeholders are those 

who need to take direct action to achieve the recommendation.

Chapter 6: IMPROVING METHODS, PRACTICE, AND PERFORMANCE 

IN FIRE AND EXPLOSION INVESTIGATION

Recommendation: Fire and explosion investigation units should operate 

using a team approach. Cooperative investigation task force arrangements with 

neighboring jurisdictions, with state-level agencies, and with ATF should be 

organized and supported.

Stakeholders: FIU Managers, NFPA 1321 Committee, Accreditation 

Bodies

Recommendation: Fire and explosion investigation units should implement 

information management practices to minimize bias.

Stakeholders: FIU Managers, NFPA 1321 Committee, Accreditation 

Bodies

Recommendation: Fire and explosion investigation units should implement 

practices to minimize potential bias by using such processes as rigorous 

adherence to the scientific method7, a technical review process, and processes to 

limit the exposure of investigators to biasing information.

Stakeholders: FIU Managers, NFPA 1321 Committee, Accreditation 

Bodies

Recommendation: Fire and explosion investigation reports should include all 

data collected, all hypotheses formulated, details of the testing process for each 

hypothesis, and the conclusions of the investigation. 

7 NFPA 921 defines the scientific method as “The systematic pursuit of knowledge 

involving the recognition and definition of a problem; the collection of data through 

observation and experimentation; analysis of the data; the formulation, evaluation and 

testing of hypotheses; and, where possible, the selection of a final hypothesis.”
xxvi

Stakeholders: Investigators, FIU Managers, Certification and 

Accreditation Bodies, NFPA 1321 and 921 Committees

Recommendation: All stakeholders (investigators, managers, lawyers, judges, 

insurance companies) must take responsibility for requiring complete and 

comprehensive fire and explosion investigation reports.

Stakeholders: Investigators, FIU Managers, Lawyers, Judges, Insurance 

Companies, Investigator Professional Associations, Certification and 

Accreditation Bodies, NFPA 921, 1033, and 1321 Committees, Educators

Chapter 7: RESEARCH NEEDS IN FIRE AND EXPLOSION 

INVESTIGATION

Recommendation: The Research Agenda developed below should be adopted 

by research funding agencies and should be carried out over the next several 

years.

Stakeholders: Fire Research Community

Chapter 8: STRENGTHENING OVERSIGHT OF FIRE AND EXPLOSION 

INVESTIGATION PRACTICES

Recommendation: Require competency and proficiency testing for fire 

investigation units both in their training and their continued monitoring of 

their work product. 

Stakeholders: FIU Managers, Accreditation Bodies, NFPA 1321 

Committee, Educators

Recommendation: Require accreditation of fire investigation units by third 

parties based on an applicable consensus standard. 

Stakeholders: NFPA 1321 Committee, Accreditation Bodies

Recommendation: Require case reviews be developed and implemented, which 

can include retrospective and proactive reviews. A multi-disciplinary review 

committee can be used to assist with this process, such as the one implemented 

by Texas SFMO.
xxvii

Stakeholders: FIU Managers, NFPA 1321 Committee, Accreditation 

Bodies

Recommendation: Require fire investigation units to adopt a quality 

assurance system.

Stakeholders: FIU Managers, NFPA 1321 Committee, Accreditation 

Bodies

Recommendation: Require all fire investigation reports to be subject to 

technical and administrative reviews. Require that case documentation 

supports the opinions within the report. 

Stakeholders: FIU Managers, NFPA 1321 Committee, Accreditation 

Bodies

Recommendation: Develop a consensus standard for the organization and 

operation of a fire and explosion investigation unit. 

Stakeholders: NFPA 1321 Committee

Recommendation: Require fire investigation units to adopt a Code of Ethics. 

Stakeholders: FIU Managers, NFPA 1321 Committee, Accreditation 

Bodies

Chapter 9: EDUCATION AND TRAINING IN FIRE AND EXPLOSION 

INVESTIGATION

Recommendation: Fire investigators should complete college-level coursework 

in algebra, chemistry, and physics, and understand how these subjects relate to 

the behavior of fire. 

Stakeholders: Investigators, FIU Managers, Certification and 

Accreditation Bodies, NFPA 1033 and 1321 Committees, Educators

Recommendation: Fire investigation units should establish a formal process 

for fire investigators’ work to be subjected to challenging technical review. This 

system should include both a review of written investigation records and 

reports as well as a verbal review that simulates testimony in depositions and 

trials. Investigators should be required to submit their work to this process 

routinely. 
xxviii

Stakeholders: FIU Managers, NFPA 1321 Committee, Accreditation 

Bodies

Recommendation: Fire Investigation Units should be required to establish a 

program that provides sufficient training and continuing education for fire 

investigators to meet the knowledge and Job Performance Requirements of 

NFPA 1033. 

Stakeholders: FIU Managers, NFPA 1321 Committee, Certification and 

Accreditation Bodies, Educators

Recommendation: Continuing education should be mandatory with a 

requirement for proof that an investigator is learning up to date information 

and reliably apply this information in the context of the scientific method. 

Stakeholders: Investigators, FIU Managers, Certification and 

Accreditation Bodies, Educators

Recommendation: More competency and proficiency training and testing 

focused on specific knowledge and skills should be developed for fire 

investigations. 

Stakeholders: Educators, Fire Research Community, Certification Bodies
1 INTRODUCTION

1-1 Introduction

This report sets out the strategic vision for the improvement of fire 

and explosion investigation in the United States. The first five 

chapters review various aspects of the field as it currently exists. The 

remaining chapters develop recommendations and a research agenda 

to move the profession forward. It was prepared by the Fire and 

Explosion Investigation Subcommittee of the Organization of 

Scientific Area Committees (OSAC).8 The scope of the report mirrors 

the scope of the profession of fire and explosion investigation as 

described in NFPA 921, Guide for Fire and Explosion Investigations, and 

NFPA 1033, Standard for Professional Qualifications for Fire Investigator. 

This strategic plan is a response to the National Academy of Sciences 

(NAS) 2009 report, “Strengthening Forensic Science in the United States: 

A Path Forward.” [NAS 2009]. 

One thing the NAS report made unequivocally clear was that fire 

investigation is a forensic science. Although there are still some 

practitioners who resist the label of forensic scientist, a body of law has 

developed around the premise that fire and explosion investigation should 

be conducted according to the scientific method as set forth in NFPA 921, 

Guide for Fire and Explosion Investigations [NFPA 921]. 

This strategic plan is an analysis of where the fire investigation profession 

is now, where it should be, and what steps should be taken to get to the 

level needed. The first of these steps have already been taken by the OSAC 

in moving NFPA 921, Guide for Fire and Explosion Investigations, and NFPA 

1033, Standard for Professional Qualifications for Fire Investigator onto the 

OSAC Registry of Standards. Inclusion on the Registry indicates that the 

8 The Fire and Explosion Investigation Subcommittee focuses on identifying and 

improving standards, guidelines and best practices for conducting investigations and 

presenting results, identifying research needs, and proposing strategies for increasing 

the reliability of investigative determinations.
2

documents are American National Standards Institute (ANSI) consensus 

standards that are well accepted by the fire and explosion investigation 

community and have met the standards of quality to be included in the 

Registry.

Having reviewed NFPA 921 and NFPA 1033, the subcommittee began to 

examine broader aspects of fire investigation and how investigations are 

conducted, guided in part by the NAS report. While the NAS report 

provided a roadmap for forensic science generally, the report did not focus 

on fire and explosion investigation. Others, like the American Association 

for the Advancement of Science, have reviewed the state of fire 

investigation and identified gaps that require filling [Almirall et al. 2017]. 

The goal of this strategic plan is to apply the breadth and depth of the NAS 

report on forensic science to fire and explosion investigation more 

specifically. This report provides challenges to all the various stakeholders 

in fire investigation and to the profession as a whole that will require many 

years to overcome.

1-2 What is Fire and Explosion Investigation?

NFPA 921 [2021] defines fire investigation as “the process of determining 

the origin, cause, and development of a fire or explosion.” 

The examination of physical evidence in fire and explosion investigation 

includes three basic types of analyses -- fire scene investigation, laboratory 

analysis of artifacts and fire debris analysis. While fire scene investigation 

occurs primarily at the scene, laboratory analysis of artifacts and fire debris 

analysis primarily occur in a laboratory setting for identification and 

evaluation of potential fire causes or detecting and identifying ignitable 

liquid residues (ILRs). Fire scene investigation, artifacts analysis, and fire 

debris analysis are most often carried out by completely different cadres of 

practitioners. The laboratory analysts are usually physical scientists with 

college degrees, while the fire scene investigators’ level of education and 

training varies widely. Currently, the standard requirements to qualify as a 

fire investigator include a high school diploma and knowledge of certain 
3

topics related to fire investigation “beyond the high school level.” [NFPA 

1033 [2022] §1.3.7]

Fire scene investigation is very challenging for several reasons, such as the 

extensive destruction of evidence caused by the fire and firefighting 

activities, the complex behavior of fire, and the inadequate understanding 

of fire chemistry and physics by some investigators. Some of the 

evaluations and determinations made by fire investigators are based on 

subjective determinations and judgments and, hence, depend on human 

cognitive factors. Depending on the extent of damage, one of a fire 

investigator’s most difficult tasks is determining the fire’s point of origin. 

“The origin of a fire is one of the most important hypotheses that an 

investigator develops and tests during the investigation. Generally, if 

the origin cannot be determined, the cause cannot be determined, and 

generally, if the correct origin is not identified, the subsequent cause 

determination will also be incorrect” [NFPA 921(2021) §18.1].

Fire investigation involves the evaluation of numerous factors, including 

witness statements, fire patterns, and fire dynamics. Analyzing these 

factors and documenting the relevant evidence is essential to 

understanding where the fire began, how and why it grew, and what 

caused the fire to start. It is also important for fire investigators to 

document any actions taken by firefighters that may have altered the scene 

and evidence so that it can be taken into account when conducting the 

investigation. 

Investigators must understand the relationship between the elements of the 

fire tetrahedron: heat, fuel, oxygen, and a sustained chemical reaction. 

Although fire investigations are complex because of the different variables 

to be considered, fires follow predictable behaviors. Initially, flames and 

smoke tend to flow up and outwards in a three-dimensional buoyant 

plume rising from the fire. In a room (often called a compartment or 

enclosure), these hot gases rise to the ceiling and then expand downward 

to form a smoke layer, charring or discoloring anything in this hot upper 

layer of the room. Patterns on surfaces in the fire enclosure will 

demonstrate how far the hot gases extended down from the ceiling. These 
4

behaviors leave behind patterns of damage that, if interpreted correctly, 

allow fire investigators to determine how the fire progressed through the 

structure, the fuels involved, and the origin. Correctly interpreting fire 

patterns, however, is challenging. [Carman 2008]

Burn patterns may be confusing and misleading because the origin will not 

necessarily be located where observable damage is most severe. This is 

particularly true for enclosure fires that grow to the point of full-room 

involvement. Full-room involvement (FRI) means that combustion is 

occurring throughout the room, though not at the same rate throughout. 

Typically, all exposed combustibles in the room are pyrolyzing to produce 

fuel gases which burn as a flame upon mixing with oxygen. Full room 

involvement generally leads to “ventilation-limited” burning, which means 

the rate of burning of the fuel gases within the room becomes limited by 

the inflow rate of air into the enclosure through ventilation pathways 

rather than being limited by the rate of fuel gases released by burning 

surfaces.

In a fully involved enclosure fire, the most intense burning occurs where 

fuel vapors encounter oxygen entering the fire enclosure, and that may not 

be where the fire originated. Such ventilation-generated burn patterns have 

been interpreted incorrectly in the past and are the subject of ongoing 

interest and research in the fire investigation community. Such 

misinterpretations have included inaccurate findings regarding the use of 

ignitable liquids and multiple fire origins, leading to incorrect 

determinations that fires are intentionally set (incendiary). 

Before making any determinations concerning the burn patterns, some 

factors that should be considered include analyzing damage to identify 

rooms which have become fully involved, analyzing the effects of 

ventilation, fire suppression effects, and the effects of “drop down” and 

structural collapse. After all the parameters are considered, and current 

understanding of their effects are applied, the investigator may be able to 

use them to form a hypothesis as to the area of origin, the spread of the fire, 

the time for development, and the heat generated during the fire. 
5

Explosion investigation differs from fire investigation in that unless there is 

a major fire after the initial explosion, the event is quite brief. NFPA 921 

defines an explosion as “the sudden conversion of potential energy 

(chemical or mechanical) into kinetic energy with the production and 

release of gases under pressure or the release of gas under pressure. These 

high-pressure gases then do mechanical work such as moving, changing, or 

shattering nearby materials.” An explosive is defined as “Any chemical 

compound, mixture, or device that functions by explosion.”

There are some explosions that are the result of criminal activity. These are 

usually investigated by federal authorities. Explosions that happen in a 

residential context are generally the result of the ignition of fuel/air 

mixtures. 

Explosions can be classified as mechanical, boiling liquid expanding vapor 

explosions (BLEVE), chemical, electrical, and nuclear. Nuclear explosions 

are well outside of the scope of this document. Explosion damage can be 

classified as low order damage, characterized by walls bulged out or laying 

down intact, or lifting of roofs; or as high order damage characterized by 

shattering of the structure, producing debris pieces. The documentation of 

explosion damage is generally similar to the documentation of fire damage. 

NFPA 921 contains an entire chapter devoted to the analysis of explosion 

damage. [NFPA 921 [2021] in Chapter 22]

At this time, forensic fire debris analysis in the laboratory focuses on the 

presence and classification of ignitable liquids, a process based on 

established scientific principles. Characterization of the ignitable liquid 

residues (ILR) is often difficult because of the liquid’s exposure to the heat 

of the fire. The validity and reliability of fire debris analysis have been 

established through organized efforts within the discipline. The chemical 

analysis and interpretation of forensic evidence from fire debris have 

benefitted from a coordinated volunteer effort to develop and continuously 

improve analytical standards. Advancements in analytical methodology 

have driven the improvements in these standards (e.g., adoption of gas 

chromatography coupled with mass spectrometry (GC-MS) as opposed to 

gas chromatography (GC) alone). Despite the progress made, there is still 

work to be done. The changing nature of ignitable liquids, such as gasoline 
6

composition and our understanding of ILRs, necessitates the continued 

refinement of these analytical standards. 

1-3 Challenges to the Fire and Explosion Investigation Profession

A central thrust of the NAS Report is the call for mandatory certification of 

individuals, mandatory accreditation of organizations, and mandatory 

standardization of methodology. The National Commission on Forensic 

Science (NCFS) [2017] also provided calls for certification, accreditation, 

and standardization. Like most forensic sciences, fire investigation has no 

mandatory requirements for any of these. The standardization of 

methodology is gradually taking place as courts decide that NFPA 921 

represents the “standard of care,” but the practitioners, who may be forced 

to follow NFPA 921 if they want their opinions admitted into evidence, are 

still allowed to practice without the benefit of certification. Accreditation of 

organizations is practically nonexistent in fire investigation with only four 

organizations having been accredited by the end of 2020.

Studies [Tinsley and Gorbett 2012, Cook 2015] have shown that current 

certification requirements do not demonstrably improve the practice of fire 

investigation. We need to make certification relevant to high standards of 

investigation performance and encourage the institutionalization of 

requirements for certification.

Fire investigator certification is available from individual states and at least 

one federal organization; however, these apply only to the employees of 

these certifying bodies, and certification by one’s employer is not the same 

as a third-party certification. Third-party certification is offered by the 

International Association of Arson Investigators (IAAI), and by the 

National Association of Fire Investigators (NAFI). Each of these 

organizations offers several different types of certification. However, 

certification is not mandatory.

As a forensic science discipline, fire investigation is challenged by the 

amount of widespread, persistent, and problematic myths affecting the 

beliefs and the behavior of its practitioners [Lentini 2006]. As long ago as 
7

1977, Boudreau, Kwan, and Faragher, working on an Aerospace 

Corporation grant from the Law Enforcement Assistance Administration 

(LEAA), conducted a “Survey and Assessment” of arson and arson 

investigation techniques. In that assessment, the authors listed seven “burn 

indicators,” but stated, “Although burn indicators are widely used to 

establish the causes of fires, they have received little or no scientific 

testing.” They recommended “that a program of carefully planned 

scientific experiments be conducted to establish the reliability of currently 

used burn indicators,” and “a handbook based on the results of the testing 

program should be prepared for field use by arson investigators” 

[Boudreau et al. 1977]. 

Three years later, the Fire Investigation Handbook was published by the 

National Bureau of Standards (NBS). Unfortunately, the “scientific studies” 

recommended in 1977 had not been conducted, and the handbook repeated 

most of the myths that had been used to incorrectly determine that an 

arson fire burned faster or hotter than normal. One of the goals of NFPA 

921, which was first published in 1992, was debunking the existing 

nonscientific myths. Lentini [2006] documents and explores the 

development, publication, and eventual debunking of many arson myths.

Over the past three decades, much has been learned about fire behavior 

and investigation, but the distribution of the knowledge among field 

investigators has not been uniform [Tinsley and Gorbett 2012]. The most 

important knowledge, which was often used to distinguish between 

incendiary fire causes and accidental fire causes in the past, can be briefly 

summarized as follows:

● The evidence left behind by fully involved accidental fires is often 

indistinguishable from evidence left by fully involved incendiary 

fires [Putorti 1997]. Artifacts once thought to indicate incendiarism 

but now known to be of little value in determining the cause of fires 

include: downward burning; charring of floors and baseboards; 

charring on the undersides of surfaces; large shiny char blisters; 

irregular fire patterns; melted metals; crazed glass; and spalled 

concrete [Lentini 2006]. 
8

● The speed with which a fire spreads in modern residences is not 

ordinarily a data point that can be used alone to determine the cause 

of the fire. Modern furnishings, particularly upholstered furniture 

made with polyurethane or polyester fiberfill cushions, can burn so 

quickly as to cause a room to become fully engulfed in flames in less 

than five minutes. Modern furnishings are in contrast to “legacy” 

furnishings made with cotton and wood, which burn with much 

lower intensity [Kerber 2012, UL 2015]. 

● The behavior of fires under differing ventilation conditions, unless 

well understood, can lead to erroneous determinations of the origin 

and cause of the fire. The ventilation (oxygen) available to a fire is 

largely responsible for the behavior of a ventilation-limited fire, 

including its temperature. In ventilation-limited fires, the amount 

and the flow path of available oxygen determine how severely a fire 

will burn at a particular location. In ventilation-limited fires, fuel 

vapors move away from the fuel source and burn near ventilation 

openings where they mix with the incoming oxygen. This will cause 

ventilation-generated burn patterns, remote from the area of origin, 

that need to be taken into account during an investigation. 

● For fully developed fires, it is more difficult for fire investigators to 

correctly determine the area(s) of origin based only on interpreting 

fire patterns, and the level of difficulty increases the longer a fire 

burns in a fully involved condition [Cox 2013]. Research conducted

since 2005 reveals that in some cases, the ability of a fire investigator 

to determine the correct area of origin in a fully involved room by 

only interpreting fire patterns may be no better than random chance 

[Carman 2008, Heenan 2010]. Tinsley and Gorbett’s 2012 study 

showed 22-26% erroneous conclusions when 587 self-selected 

investigators, working independently, viewed photos and data from 

a fire that burned for one minute beyond flashover. These results 

were similar to the 31% erroneous conclusions found in a 70-second–

beyond-flashover study conducted in 2007 [Heenan 2010]. 

Another challenge to the accurate presentation of fire investigation 

evidence in court is the lack of appreciation on the part of lawyers and 
9

judges for the lack of expertise of some in the fire investigation community. 

Judges are called upon to be “gatekeepers” for forensic science evidence, 

but generally are reluctant to exclude expert testimony, for fear of being 

overturned on appeal, even though the standard of review, “abuse of

discretion” is very deferential. This reluctance is especially present in the 

criminal courts, where judges are reluctant to exclude forensic science 

witnesses. Exclusions are much more common in civil cases, where both 

sides tend to have more resources than the average criminal defendant 

[NAS 2009 p. S-8].

Responding to the challenges of fire investigation requires resources, and 

the availability of resources is not close to uniform. Federal agencies 

typically have better resources than state and local agencies, but no 

agencies seem to have enough. Resources could also be applied to salaries 

so that fire investigation agencies could attract better-educated applicants. 

Improving the quality of the applicant pool cannot be done with the 

resources currently available for personnel.

REFERENCES

Almirall, J., Arkes H., , Lentini, J., Mowrer, F., and Pawliszyn, J. (2017), 

Forensic Science Assessments: A Quality and Gap Analysis Fire 

Investigation, American Association for the Advancement of Science, DOI: 

10.1126/srhrl.aag2872,

https://www.aaas.org/sites/default/files/reports/Fire%20Investigation.

pdf

Boudreau J.F. et al. (1977). Arson and Arson Investigation: Survey and 

Assessment. Law Enforcement Assistance Administration (LEAA), U.S. 

Department of Justice, pp.1-132. 

https://www.ncjrs.gov/pdffiles1/Digitization/147389NCJRS.pdf

Brannigan F.L., Bright R.G., and Jason N.H. (1980). Fire Investigation 

Handbook, National Bureau of Standards Handbook 134, Washington, DC: 

US Government Printing Office. (out of print)

https://www.ojp.gov/pdffiles1/Digitization/73598NCJRS.pdf
10

Carman, S. (2008). Improving the Understanding of Post-Flashover Fire 

Behavior. Proceedings of the 3rd International Symposium on Fire Investigations 

Science and Technology (ISFI), NAFI, Sarasota, FL. 

http://www.carmanfireinvestigations.com/

Cook, D.E. (2015) Have We Learned The Lessons Of The Willingham Case?, A 

National Survey Of Fire Investigators, A Research Project Submitted To 

National University in Partial Fulfillment of The Requirements for the 

Degree of Master Of Forensic Sciences. 

http://www.forensicresearchdigest.com/yahoo_site_admin/assets/docs/

Cook_-_Thesis_FINAL_DRAFT_-_AS_BOUND.259175111.pdf

Cox, A. (2013). Origin Matrix Analysis: A Systematic Methodology for the 

Assessment and Interpretation of Compartment Fire Damage. Fire and 

Arson Investigator Journal, International Association of Arson Investigators, 

Vol. 64, pp. 37-47

Heenan D. (2010). History of the Post Flashover Ventilation Study. 

Presentation made at CAAI, November 2010. 

https://app.box.com/s/rzychcvtdjm738ns3ko7ou69fayjd4xy

Kerber, S. (2012) Analysis of Changing Residential Fire Dynamics and Its 

Implications on Firefighter Operational Timeframes, Fire Technology, 48: 

865. doi:10.1007/s10694-011-0249-2.

https://doi.org/10.1007/s10694-011-0249-2

Lentini J. (2006), The Mythology of Arson Investigation, in Proceedings of the 

2nd International Symposium on Fire Investigations Science and Technology

(ISFI), NAFI, Sarasota, FL. 

https://drive.google.com/drive/folders/1d_V2v8q8fkWAmsxCD3icf6QiLYziR47

National Academy of Sciences (2009), Committee on Identifying the Needs 

of the Forensic Sciences Community; Committee on Applied and 

Theoretical Statistics, National Research Council, Strengthening Forensic 
11

Science in the United States: A Path Forward. 

https://www.ncjrs.gov/pdffiles1/nij/grants/228091.pdf

National Commission on Forensic Science (2017), Work Products of the 

FCFS, 

https://www.justice.gov/archives/ncfs/work-products-adoptedcommission

NFPA 921: Guide for Fire and Explosion Investigations, 2021 edition, NFPA, 

Quincy, MA. 

http://www.nfpa.org/codes-and-standards/all-codes-and-standards/listof-codes-and-standards?mode=code&code=921

NFPA 1033: Standard for Professional Qualifications for Fire Investigator, 2022

edition. NFPA, Quincy, MA. 

http://www.nfpa.org/codes-and-standards/all-codes-and-standards/listof-codes-and-standards?mode=code&code=1033

Putorti A. (1997), Full Scale Room Burn Pattern Study. NIJ Report 601-97, 

National Institute of Justice, Washington, D.C., December 1997. 

https://www.nist.gov/publications/full-scale-room-burn-pattern-studynij-report-601-97

Texas SB 1287 (2015) http://www.fsc.texas.gov/texas-forensic-sciencecommission-forensic-analyst-licensing-program

Tinsley A.T. and Gorbett G.E. (2012), Fire Investigation Origin 

Determination Survey. International Symposium on Fire Investigation Science 

and Technology (ISFI), pp. 53-68. 

https://ssem.eku.edu/sites/ssem.eku.edu/files/files/Gorbett%20-

%20FIRE%20INVESTIGATION%20ORIGIN%20DETERMINATION.pdf

Underwriters Laboratories. (2015), Modern Residential Fires. 

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12

2. CURRENT STRUCTURE OF THE FIRE AND 

EXPLOSION INVESTIGATION COMMUNITY, 

AND THE NEED FOR INTEGRATED 

GOVERNANCE.

2-1 Introduction

The fire investigation community consists of public sector and private 

sector individuals who either investigate fire scenes to determine the origin 

and cause or review the work of others who have made such 

determinations. These individuals are aided in these efforts by a broad 

array of experts in other disciplines. 

Most public sector fire investigators work for either state or local agencies. 

Some of these are law enforcement positions, and some are under the fire 

department without law-enforcement powers. In such cases, the fire 

department personnel make their determinations, and then, if criminal 

activity is indicated, they turn their reports over to law enforcement. In 

court proceedings, the fire investigator often serves as the prosecution’s 

chief witness.

In the federal system, fire investigation is almost always carried out by the 

Bureau of Alcohol, Tobacco, Firearms, and Explosives (ATF). ATF agents 

are available to assist state and local investigators, and in the case of a 

significant fire or explosion, ATF’s National Response Team can be 

mobilized to focus numerous personnel and other resources to a site.

Public sector investigators are typically tasked with determining whether a 

fire was the result of a criminal or unintentional act. In many instances, 

once a fire has been determined to be the result of a non-criminal event, the 

public sector investigators withdraw, leaving any additional investigation 

to the private sector. 
13

Private sector investigators are employed by fire investigative or 

engineering firms and insurance companies. They are engaged by 

insurance companies, manufacturers, attorneys, or public agencies to 

investigate fire origin and cause. These investigators’ roles may vary 

depending upon whom they are engaged by and the purpose of the 

investigation. The investigator may be asked to address issues related to 

insurance coverage, issues arising out of subrogation involving a 

manufacturer’s product, or assisting a public agency in dealing with a 

specific need associated with their investigation. 

Both public and private sector investigators rely on chemists to analyze fire 

debris to determine the presence of ignitable liquid residues. Criminal 

prosecutions or denials of insurance proceeds are likely to follow if 

gasoline or other ignitable liquid residues are detected in places where they 

do not belong. Chemists also can assist in the identification of substances 

such as vegetable oils that are capable of undergoing spontaneous 

combustion (e.g., oil-soaked rags), comparing ignitable liquid residues with 

potential sources, analysis of explosives and general substance 

identification.

Investigators may rely on engineers when evaluating many factors relevant 

to understanding a fire event. Engineers evaluate electrical and mechanical 

devices to determine if they could be potential ignition sources. Engineers 

evaluate fire protection and signaling systems to determine the role that 

they played during a fire. Engineers calculate the movement of heat and 

smoke through structures, calculate the dispersion of flammable and toxic 

gases in leak scenarios, and calculate radiant heat transfer which may lead 

to ignition of items remote from the initial fire source.

In addition to the determination of whether coverage is available or 

appropriate, insurance companies also have a strong incentive to 

determine the cause of an accidental fire, which may have been caused (or 

exacerbated) by someone other than their insured. For example, if a 

defective appliance can be shown to have caused a fire, that may prompt 

the insurance company to seek reimbursement, through subrogation, from 

the manufacturer of that product. The same applies to service providers 

such as architects, electricians, fire protection system designers and 
14

installers, roofers, welders, or anyone else who has provided a service in a 

negligent (or allegedly negligent) fashion that caused a fire. These potential 

defendants often have liability insurance, and their insurance carriers may 

retain additional fire investigation professionals. Subrogation litigation is a 

major driver for the private sector fire investigation business. Fire-related 

civil litigation not driven by subrogation frequently involves claims of 

personal injury or wrongful death.

It is in the context of subrogation litigation (or potential litigation) that 

engineers such as mechanical engineers and electrical engineers are often 

brought into a fire investigation. Engineers may also be brought in to assess 

certain potential accidental causes.

2-2 Oversight

In the public sector, government entities that receive federal funds for 

criminal investigations, including crime laboratories and fire marshal’s 

offices, are required to have in place a “Coverdell entity.” This entity is 

named for the Paul Coverdell National Forensic Sciences Improvement Act 

of 2000 [Public Law 106-561], which governs the provision of grant money 

(Coverdell grants) to various agencies. Under the Justice for All Act of 2004 

[Public Law 108-405], agencies applying for Coverdell Program grants are 

required to certify that a government entity exists and appropriate 

processes are in place to conduct independent external investigations into 

allegations of serious negligence or misconduct substantially affecting the 

integrity of forensic results. 

Some states have “forensic science commissions” to serve this function, but 

the function is also carried out in some places by Internal Affairs Divisions 

or an Office of Inspector General. The extent and rigor of oversight by 

Coverdell entities vary widely depending on the jurisdiction. More 

information on the Coverdell Program is available from the National 

Institute of Justice (NIJ) website. 

The Texas Forensic Science Commission (TX FSC) is an example of a 

Coverdell entity that maintains a rigorous focus on its mission. The TX FSC 
15

has investigated numerous claims of problems with arson investigations 

and in 2011 issued a 17-item list of recommendations for the conduct of 

public sector fire investigations and prosecutions. They have also examined 

allegations of problems with bite mark comparisons, DNA mixture issues, 

bloodstain pattern analysis problems, and microscopic hair comparisons.

2-3 Licensing

In most states, private-sector fire investigators (PIs) are required by law to 

register and pay fees as private investigators. Law enforcement officials are 

exempt from such requirements, and there are a few states that exempt 

“forensic experts” from their private investigation law. There are numerous 

provisions with many PI laws, depending on the state, which may provide 

exemptions to these PI licensing requirements. In some states, in addition 

to holding a PI license, the individual investigator may also be required to 

be certified as a fire investigator. As of 2017, only five states (Alaska, Idaho, 

Mississippi, South Dakota, and Wyoming) do not require private 

investigators to be licensed.

2-4 Research

Since the first publication of NFPA 921 in 1992, fire investigation began to 

see an increase in research through a variety of public and private efforts. 

Some of the federal funding for this research was offered through NIJ and 

NIST [Shanley et al. 1997, Putorti 1997, Madrzykowski 2000]. NIST’s 

Building Fire Research Laboratory published much of their ignition and 

heat release rate data through an online database that was useful to fire 

investigators. However, this database is no longer available. 

Since the 2009 NAS Report, wherein fire investigation was identified as a 

forensic science discipline, there has been an increase in funding of 

research in fire investigations. NIJ has funded much of the recent work 

(https://www.nij.gov/topics/law-enforcement/investigations/firearson/pages/welcome.aspx). Recent research has included an examination 

of the Forensic Analysis of Ignitable Liquid Fuel Fires in Buildings [Mealy, 
16

Wolfe & Gottuk 2013]. Other projects have involved collaboration between 

outside contractors and the ATF Fire Research Laboratory (FRL) in 

Ammendale, MD. In 2016, Underwriters Laboratories (UL) embarked on a 

research program funded by NIJ to study the effects of ventilation on both 

firefighter safety and fire pattern production. 

Results of fire research are presented in NIJ reports, in peer-reviewed fire 

journals (e.g., Fire Technology), at meetings such as the Fire and Materials 

Conference, the IAAI’s Annual Training Conference, the International 

Symposium on Fire Investigation Science and Technology (ISFI), and in 

Fire and Arson Investigator, the official Journal of the IAAI. 

It is expected that the science of fire investigation will be moved forward 

by this additional research. Research conducted by public or private 

entities, particularly when done for a specific investigation, may not be 

published. Despite the research thus far, there are still many areas in fire 

investigation where there has been little to no research. Additional research 

is needed to validate forensic methods that assist with origin and cause. 

Current research needs are identified in Chapter 7.

2-5 Governance

Except for cases in which a Court decides whether a fire investigator will 

be allowed to render opinion testimony, fire investigators are largely 

governed by two professional organizations. The International Association 

of Arson Investigators (IAAI) founded in 1949, now has over 10,000 

members, of whom more than 2,000 are certified. The National Association 

of Fire Investigators (NAFI), founded in 1961, has over 6,500 members, of 

whom more than 5,000 are certified. Both of these organizations offer 

certification at different levels, and both organizations provide their 

members with publications directing them to the latest research. Each 

organization also has a code of ethics, to which members must subscribe. 
17

Table 2-1. Certification available to fire investigators in 2018.

Designation Organization 2017 Cost (USD) Comment

Certified Fire 

Investigator 

(CFI)

IAAI 195 (member)

570 (non-member)

Fire Investigation 

Technician (FIT)

IAAI 90 (member)

325 (non-member)

Evidence 

Collection 

Technician (ECT)

IAAI 280 (member)

490 (non-member)

Certified 

Instructor (CI)

IAAI 150 (member)

395 (non-member)

Certified Fire & 

Explosion 

Investigator 

(CFEI)

NAFI 125 (members 

only)

Certified Vehicle 

Fire Investigator 

(CVFI)

NAFI 125 (Members 

only)

Requires 

course 

completion. 

Cost >700

Certified Fire 

Investigation 

Instructor (CFII)

NAFI 75-125 (depends 

on course 

completed, 

members only)

Requires 

course 

completion. 

Cost >700

Certified Fire 

Investigator 

(CFI)

ATF N/A Available to 

ATF Special 

Agents only

Certified Fraud 

Examiner (CFE)

Association of 

Certified Fraud 

Examiners 

(ACFE)

400 (members 

only)

Must join 

ACFE

Certified 

Insurance Fraud 

Investigator 

(CIFI)

International 

Association of 

Special 

200 (member)

400 (non-member)
18

Investigation 

Units (IASIU)

Certified 

Insurance Fraud 

Analyst (CIFA)

IASIU 200 (members 

only)

Annual dues 

80

Certified Fire 

Protection 

Specialists 

(CFPS)

National Fire 

Protection 

Association 

(NFPA)

350 + 125/year Work and 

education 

requirements 

Various State Agencies N/A Employer 

based

In December 2016, the National Commission on Forensic Science (NCFS) 

approved a document entitled “Views of the Commission: Accreditation of 

Forensic Science Certification Bodies.” The document [NCFS 2016] states, 

“It is the view of the Commission that certification bodies should:

● Seek compliance to ISO/IEC 17024 Conformity Assessment – General 

Requirements for Bodies Operating Certification of Persons. This 

process should be accomplished within 10 years of implementation.

● Be accredited in accordance with the requirements of ISO/IEC 17024 by 

an accreditation body operating in accordance with ISO/IEC 17011—

General Requirements for Accreditation Bodies Accrediting Conformity 

Assessment Bodies and signatory to the International Accreditation 

Forum (IAF) Multilateral Arrangement (MLA).

● Collaborate with other certification bodies to develop uniform 

certification requirements.

● Ensure that certification examinations are continually reviewed to 

incorporate new technologies and remove obsolete information.”

The IAAI Certification Program is accredited by both the Professional 

Qualifications Board (The Pro Board) and the Forensic Specialties 

Accreditation Board (FSAB). None of the NAFI programs are accredited, 

but NAFI is reportedly in the process of applying for FSAB accreditation.
19

Other professional organizations that affect fire investigation include the 

National Fire Protection Association (NFPA), International Fire Marshals

Association (IFMA), Society of Fire Protection Engineers (SFPE), National 

Association of State Fire Marshals (NASFM), ASTM International, 

International Association of Special Investigative Units (IASIU), 

Association of Certified Fraud Examiners (ACFE), the National Association 

of Subrogation Professionals (NASP) and the American Academy of 

Forensic Sciences (AAFS). 

The NFPA is a global nonprofit organization established in 1896, which 

now has over 60,000 members. NFPA’s mission is to reduce the worldwide

burden of fire and other hazards on the quality of life by providing and 

advocating consensus codes and standards, research, training, and 

education. NFPA promulgates NFPA 921 and NFPA 1033 which apply 

directly to fire investigations. NFPA also has several sections, including the 

International Fire Marshals Association (IFMA). NFPA publishes the Fire 

Protection Handbook, now in its 20th edition, and jointly publishes the peerreviewed journal Fire Technology with SFPE and Springer.

SFPE also publishes the Handbook of Fire Protection Engineering, now in its 

fifth edition. Founded in 1950, SFPE has over 4,000 members, representing 

those practicing in the fields of fire protection engineering and fire safety 

engineering. SFPE's mission is to define, develop, and advance the use of 

engineering best practices; expand the scientific and technical knowledge 

base; and educate the global fire safety community, to reduce fire risk. 

Additionally, SFPE offers courses in numerous areas of engineering that 

are of interest to fire investigators. 

The principal membership of NASFM comprises senior fire officials in the 

United States and their top deputies. The primary mission of NASFM, 

established in 1989, is to protect human life, property, and the environment 

from fire and related hazards. A secondary mission of NASFM is to 

improve the efficiency and effectiveness of State Fire Marshals' operations. 

In addition to its principal membership of State Fire Marshals, NASFM has 

several categories of membership to allow companies, associations, 

academic and research institutions, and individuals who support NASFM's 

mission to contribute in meaningful ways. State Fire Marshals’ 
20

responsibilities may vary from state to state, but Marshals tend to be 

responsible for fire safety code adoption and enforcement, fire and arson 

investigation, fire incident data reporting and analysis, public education 

and advising governors and state legislatures on fire protection.

ASTM International (formerly the American Society for Testing and 

Materials) promulgates more than 12,000 individual standards covering all 

aspects of products and services. ASTM publishes an 80-volume Annual 

Book of Standards. Founded in 1898, ASTM International is one of the 

world’s largest international standards development organizations. There 

are more than 30,000 members of the organization who hail from more 

than 140 countries. ASTM Committee E30 on Forensic Sciences 

promulgates standards for evidence handling, reporting, and fire debris 

analysis, among other forensic science disciplines. 

Founded in 1984 by a group of insurance industry fraud investigators, the 

International Association of Special Investigation Units (IASIU) is a nonprofit organization dedicated to: 

● promoting a coordinated effort within the industry to combat 

insurance fraud; 

● providing education and training for insurance investigators; 

● developing greater awareness of the insurance fraud problem; 

● encouraging high professional standards of conduct among 

insurance investigators; and 

● supporting legislation that acts as a deterrent to the crime of 

insurance fraud. 

Established in 1988, the Association of Certified Fraud Examiners (ACFE) is 

a professional organization of fraud examiners. Its activities include 

producing fraud information, tools, and training. The ACFE grants the 

professional designation of Certified Fraud Examiner. There are currently 

over 85,000 members. 

The National Association of Subrogation Professionals (NASP), whose 

members have a keen interest in fire investigations, was founded in 1998 to 
21

meet the needs of the subrogation industry. NASP offers a monthly 

magazine, an annual national seminar, and numerous local seminars. 

The American Academy of Forensic Sciences, founded in 1948, consists of 

nearly 7000 members practicing in 12 distinct forensic science disciplines. 

The Criminalistics section of the Academy includes fire investigators and 

fire debris analysts.

2-6 Standards for Fire Investigators

Quality in fire investigation, and indeed in all of the forensic science 

disciplines, is comprised of three elements: certification for individuals, 

accreditation for organizations, and standardization of methods. Figure 2-1 

shows these elements as the sides of the Quality Triangle in Forensic 

Science. 
22

Figure 2-1. The Quality Triangle in Forensic Science. The Quality Triangle 

is credited to Lawrence Pressley, former Quality Assurance Director at the 

FBI Laboratory. [Lentini 2018]

There are two overarching consensus documents in fire investigation. 

NFPA 1033, Standard for Professional Qualifications for Fire Investigator, and 

NFPA 921, Guide for Fire and Explosion Investigations. These documents meet 

the requirements for voluntary consensus documents. Both documents are 

regularly used in court to challenge the qualifications, methodology, and 

analysis of the fire investigator. These two documents incorporate other 

standards by reference, specifically ASTM standards promulgated by 

Committee E30 on Forensic Sciences dealing with the collection, 

preservation, and handling of evidence and data, as well as reporting of 

opinions. Both NFPA 921 and NFPA 1033 are listed on the OSAC Registry. 

The Fire and Explosion Investigation Subcommittee has submitted 

recommendations for improving both of these documents to NFPA.
23

NFPA 1033 [2022] outlines the minimum education, knowledge, and skills 

necessary to be a fire investigator. This standard applies to both public and 

private investigators. NFPA 1033 was first published in 1987 and is in its 

sixth edition. It is revised on a 5-year schedule.

NFPA 921 [2021] outlines the methods, practices, and procedures for 

properly conducting fire investigations. NFPA 921 was first published in 

1992 and is now in its tenth edition. Courts have relied on NFPA 921 as an 

authoritative source of information about how fire investigations should be 

performed.9 

9 See Russell v. Whirlpool Corp., 702 F.3d 450, 455 (8th Cir. 2012) (stating that although 

NFPA standards are not controlling, if the investigators purport to use NFPA 921, they 

need to “reliably apply” NFPA instructions); Bryte ex rel. Bryte v. Am. Household, Inc., 

429 F.3d 469, 478 (4th Cir. 2005) (upholding the district court’s exclusion of fire 

investigation causation testimony where a fire investigator failed “to exclude ‘[a]ll other 

reasonable origins and causes’” as mandated by NFPA 921 (alteration in original) 

(quoting NAT’L FIRE PROT. ASS’N, NFPA 921: GUIDE FOR FIRE AND EXPLOSION 

INVESTIGATIONS ¶ 2-3.6 (1998 ed. 1998))); Fireman’s Fund Ins. Co. v. Canon U.S.A., 

Inc., 394 F.3d 1054, 1059 (8th Cir. 2005) (holding that the district court did not abuse its 

discretion in concluding that the fire investigators failed to apply an NFPA 921 

evidentiary standard reliably to the facts of the case); Werth v. Hill-Rom, Inc., 856 F. 

Supp. 2d 1051, 1060 (D. Minn. 2012) (excluding expert-fire-investigator testimony due to 

the expert’s failure to rely on NFPA 921 and, in so doing, stating that “[s]imply put, the 

experts’ failure to disclose their reliance on NFPA 921—in their initial Report, their 

Supplemental Report, their depositions, or at any other point in discovery—would 

alone justify excluding their opinion”); Travelers Indem. Co. v. Indus. Paper & 

Packaging Corp., No. 3:02–CV–491, 2006 WL 1788967, at *4–5 (E.D. Tenn. June 27, 2006) 

(denying, in part, motion in limine to exclude fire-expert testimony where expert 

methodology was “consistent with NFPA 921”); Workman v. AB Electrolux Corp., No. 

03-4195-JAR, 2005 U.S. Dist. LEXIS 16306, at *31 (D. Kan. Aug. 8, 2005) (allowing 

admission, in part, of evidence because the investigator’s methodology comported with 

NFPA 921 standards); Tunnell v. Ford Motor Co., 330 F. Supp. 2d 707, 725 (W.D. Va. 

2004) (concluding that the expert’s testimony “was based on his investigation of the 

cause of the fire, an investigation which was conducted in accordance with the 

professional standards and scientific methodology . . . set forth in NFPA 921”); TNT Rd. 

Co. v. Sterling Truck Corp., No. 03- 37-B-K, 2004 U.S. Dist. LEXIS 13463, at *9, *17–18 (D. 

Me. July 19, 2004) (allowing admission of evidence that “substantially complied with 

the NFPA standard”); Ind. Ins. v. Gen. Elec. Co., 326 F. Supp. 2d 844, 851–53 (N.D. Ohio 

2004) (finding that reliance on a “suspect investigation . . . impugns the reliability of [the 

expert’s] analysis”); Royal Ins. Co. of Am. v. Joseph Daniel Constr., Inc., 208 F. Supp. 2d 
24

NFPA 921 has been adopted as the standard of care in a number of cases.10

In 2004, the American Bar Association House of Delegates called for all 

forensic science practitioners to be certified, for agencies that employ those 

practitioners to become accredited, and for the certified practitioners to 

follow standard methods. The 2009 NAS Report called for the same things, 

although NAS additionally stated that all of these requirements should be 

mandatory. The National Commission on Forensic Science also 

supported universal certification of forensic science practitioners [NCFS 

2016] Mandatory certification and best practices should be encouraged.

Although certification is available in fire and explosion investigation, there 

is almost no accreditation of fire investigation units. (As used in this text, 

certification applies to individuals, and accreditation applies to 

organizations.) As of 2019, there were three private sector agencies and 

one public sector agency accredited by the American Association for 

Laboratory Accreditation (A2LA) to conduct fire scene investigations. ATF 

National Response Team is accredited by ANSI National Accreditation 

Board (ANAB). The OSAC Fire and Explosion Investigation Subcommittee 

is looking forward to promulgating standards for the accreditation of fire 

investigation agencies, but this work is just beginning. An NFPA 

423, 426–27 (S.D.N.Y. 2002) (“A comparison of [the expert’s] methodology and the six 

steps of the NFPA 921 methodology reveals that his conclusions were based on these 

recognized standards and not merely his subjective belief.”); Snodgrass v. Ford Motor 

Co., No. 96-1814(JBS), 2002 U.S. Dist. LEXIS 13421, at *48, *56–57 (D.N.J. Mar. 28, 2002) 

(allowing expert to testify to his opinions on fire causation as long as said opinions did 

not rely on unreliable statistics); Chester Valley Coach Works v. Fisher-Price, Inc., No. 

99 CV 4197, 2001 WL 1160012, at *8–13 (E.D. Pa. Aug. 29, 2001) (noting that an expert’s 

deviations from NFPA 921 methodologies gave the court “serious doubts as to the . . . 

conclusions that [the expert] reached”); Travelers Prop. & Cas. Corp. v. Gen. Elec. Co., 

150 F. Supp. 2d 360, 365–66 (D. Conn. 2001) (remarking that an expert’s methods were 

consistent with “the principles of NFPA 921”). But see Schlesinger v. United States, 898 

F.Supp.2d 489, 504 (E.D.N.Y. 2012) (“courts frequently exclude expert testimony for 

failure to comply with NFPA 921 in circumstances where the expert explicitly relies on 

NFPA 921 in reaching his or her conclusion,“ but “the Court is aware of no court in this 

circuit that has refused to admit expert testimony in an arson case because his or her 

opinion was based on a methodology other than that prescribed in NFPA 921 ... .”).

10 See id.
25

Committee has been created to develop the standard, and a draft standard 

has been proposed by the Fire and Explosion Investigation Subcommittee 

of OSAC. The standard, NFPA 1321, is in the early developmental stages 

prior to beginning full public review and initial revision cycle. Such a 

standard will provide the basis for completion of the Quality Triangle in 

Forensic Science for fire and explosion investigations. 

2-7 Conclusions

Today’s fire investigation profession offers numerous avenues for 

professional development. Fire investigators and the agencies that employ 

them are urged to avail themselves of these opportunities. Staying abreast 

of current research is required if an investigator wishes to become and 

remain credible. Investigators are encouraged to join professional 

organizations, attend training, read journals, and most importantly, 

become certified.

The methodology of fire investigation has changed dramatically over the 

last three decades, as the industry has moved from art to science. The 

profession has chosen to use the open committee process at NFPA so that 

everyone has an opportunity to participate. The content of the NFPA 921 

and NFPA 1033 documents are the result of thousands of public comments 

and hundreds of face-to-face meetings. All investigators and agencies are 

encouraged to become involved in the process.

REFERENCES

Lentini, J., Scientific Protocols for Fire Investigation, 3rd Edition, CRC Press, 

2018.

Madrzykowski, D., The Future of Fire Investigation, Fire Chief, October 

2000. 

http://www.interfire.org/pdf/Madrzykowski.pdf

Mealy, Wolfe, & Gottuk, (2013), Forensic Analysis of Ignitable Liquid Fuel 

Fires in Buildings, NCJRS, Document # 241441.

https://www.ncjrs.gov/pdffiles1/nij/grants/241441.pdf
26

National Commission on Forensic Science (2017), Work Products of the 

NCFS, 

https://www.justice.gov/archives/ncfs/work-products-adopted-commission

Putorti A. (1997), Full Scale Room Burn Pattern Study. NIJ Report 601-97, 

National Institute of Justice, Washington, D.C., December 1997. 

https://www.nist.gov/publications/full-scale-room-burn-pattern-studynij-report-601-97

Shanley, J. H. Jr.; et al.;(1997) “Federal Emergency Management USFA Fire 

Burn Pattern Tests.” Report of the United States Fire Administration 

Program for the Study of Fire Patterns, FA 178; p. 221. 

https://app.box.com/s/z2ws7harx94levwxnf7cy3e2x0akz3fg
27

3. THE ADMISSION OF FIRE AND EXPLOSION 

INVESTIGATION EVIDENCE IN LITIGATION

3-1 Science and the Law

As Justice Blackmun observed in the Daubert decision, “There are 

important differences between the quest for truth in the courtroom and the 

quest for truth in the laboratory. Scientific conclusions are subject to 

perpetual revision. Law, on the other hand, must resolve disputes finally 

and quickly.” 

According to the 2009 NAS report, 

“The adversarial process relating to the admission and 

exclusion of scientific evidence is not suited to the task of 

finding ‘scientific truth.’ The judicial system is encumbered by, 

among other things, 

● judges and lawyers who generally lack the scientific 

expertise necessary to comprehend and evaluate forensic 

evidence in an informed manner, 

● trial judges (sitting alone) who must decide evidentiary 

issues without the benefit of judicial colleagues and often 

with little time for extensive research and reflection, and 

● the highly deferential nature of the appellate review of 

afforded trial courts’ Daubert rulings.

Given these realities, there is a tremendous need for the 

forensic science community to improve. Judicial review, by 

itself, will not cure the infirmities of the forensic science 

community.”

It is, therefore, incumbent upon the practitioners of forensic science, 

including fire investigators, to improve their reliability through leadership, 
28

professionalism and valid research, to meet the needs of the criminal and 

civil justice systems.

The trial court judge has always controlled the admission of evidence, 

including expert evidence, at trial, but empirical research has shown that 

the admission decision varies by factors such as which party is proposing 

the testimony and the type of case. Considering the status of the case and 

the state of the law, prosecutors, defense attorneys, and civil litigators must 

therefore decide, often with input from their experts, which evidence to 

attempt to present. In criminal cases, judges may be wish to avoid appeals

by having a permissive approach to admissibility and allowing the jury to 

decide which side has the best experts.11. In criminal cases, expert

testimony is commonly allowed.12. As a practical matter, appellate court 

decisions often involve evaluation of testimony from civil cases. [NAS 

2009] Yet because of the deferential “abuse of discretion” standard applied 

to admissibility decisions, these appellate cases may not necessarily reflect 

the overall approach taken at the trial court level, where decisions are 

commonly unwritten or unpublished. The appellate record for challenges 

to fire investigations will be discussed below.

Before the 1993 Daubert decision, the prevailing authority on admissibility 

of scientific evidence was the Frye case, a 1923 case from the Court of 

Appeals for the District of Columbia.13 In this murder case, the defense 

attempted to introduce a “systolic blood pressure deception test,” a 

predecessor of the polygraph with the same function, which the expert 

would testify that the defendant passed. After the trial court did not allow 

the testimony, the defendant appealed. On appeal, the court held that to be 

admissible, a scientific technique had to be “generally accepted by the 

relevant scientific community.” Even after the Supreme Court decision in 

11 Risinger, D. M., [2000] “Navigating Expert Reliability: Are Criminal 

Standards of Certainty Being Left on the Dock?” 64 ALB. L. REV. 99, 101, 

104.

12 See id. 

13 Frye v. United States, 293 F. 1013, 1013 (D.C. Cir. 1923).
29

Daubert in 1993 changed the standard of review in federal court, a number 

of states continue to apply Frye for admissibility determinations in their 

state courts. 

In its 1993 Daubert ruling, the Supreme Court provided significant 

guidance to judges on how to consider proposed testimony in the form of 

non-exclusive list of factors a trial court judge could consider, including the 

Frye general acceptance factor. Even though many “friends of the court” 

warned that moving away from general acceptance to a broader standard 

for admission would result in courts being bombarded with “junk science,” 

the Daubert decision seems to have encouraged more reliability challenges

or at least has resulted in judges paying closer attention to their 

responsibility as gatekeepers. [Risinger 2000] As a result of increased

scrutiny overall, there have been far more experts challenged since Daubert

than were challenged beforehand.

In 2000, the Federal Rules of Evidence were amended to reflect the 

Supreme Court’s language from the Daubert trilogy.14 Rule 702, which 

formerly required “scientific, technical, or specialized knowledge” that 

“will assist the trier or fact” for testimony to be qualified, now requires 

that:

(a) the expert’s scientific, technical, or other specialized 

knowledge will help the trier of fact to understand the evidence 

or to determine a fact in issue;

(b) the testimony is based on sufficient facts or data;

(c) the testimony is the product of reliable principles and 

methods; and

(d) the expert has reliably applied the principles and methods 

to the facts of the case.

As of 2019, a majority of states have adopted the Daubert standard for use 

in their state courts, while a smaller number of states still operate under 

14 The “Daubert trilogy” consists of the original Daubert decision, 509 U.S. 

579 [1993], the GE v. Joiner decision, 522 U.S. 136 [1997] and the Kumho v. 

Carmichael decision, 526 U.S. 137 [1999].
30

the Frye standard. At least three states (NV, ND, VA) have a unique statespecific standard [Morgenstern, 2020] In all jurisdictions, the gatekeeping 

standard is primarily a standard intended to ensure the reliability of 

expert testimony.

3-2 Reports and Testimony

Documentation is an essential part of the scientific method. According to 

NFPA 921, “Thorough and accurate documentation of the investigation is 

critical because it is from this compilation of factual data that investigative 

opinions and conclusions can be supported and verified” [NFPA 921-2021

at 16.1.2]. Reports serve two functions. The first is to communicate the 

investigator’s methodology and findings, while the second is to aid the 

investigator in recreating his findings and thought processes sometime in 

the future. Most fire investigations end with the preparation of an expert 

report. 

The length, content, and level of detail required in a report vary widely 

depending on the investigator’s jurisdiction and assignment. In the Federal 

system, the report format is dictated by Federal Rule of Civil Procedure 26 

for civil cases and Federal Rule of Criminal Procedure 16 for criminal cases. 

Some states will have similar rules, but the level of disclosure var by 

jurisdiction. Generally, the rules require greater levels of disclosure in 

reports created for use in civil cases. In some jurisdictions, however, the 

law will not require any expert report. Whether a report is needed or not, 

discovery of an expert’s opinion may be required by rules of disclosure,

and if so, the disclosure would require a document filed by sponsoring 

counsel that states the expert’s opinions. In jurisdictions where sponsoring 

counsel summarizes the expert’s opinion, it is important for the expert to 

coordinate closely with counsel to make sure the disclosure is accurate.

In some cases, discovery may also include expert depositions, involving 

sworn testimony by the expert who is questioned by adverse counsel 

without a judge present. Other jurisdictions do not allow expert 

depositions, so the attorneys learn what the expert will say during the trial. 

In still other jurisdictions the only opinions an expert is allowed to express 

at trial are what is in the “four corners” of the expert’s report.
31

As for criminal cases, a small number of states (FL, IA, IN, NH, and VT), 

allow depositions in criminal cases, and every person on the witness list of 

both sides may be subject to being deposed. In federal criminal cases and in 

most states, depositions are generally not allowed. It is thus important for 

an investigator to be familiar with the rules governing discovery.

According to Federal Rule of Civil Procedure 26, an expert’s report must 

contain:

(1) a complete statement of all opinions the witness will express and 

the basis and reasons for them;

(2) the facts or data considered by the witness in forming them;

(3) any exhibits that will be used to summarize or support them;

(4) the witness's qualifications, including a list of all publications 

authored in the previous 10 years;

(5) a list of all other cases in which, during the previous 4 years, the 

witness testified as an expert at trial or by deposition; and

(6) a statement of the compensation to be paid for the study and 

testimony in the case.

In criminal cases, the report requirements are only slightly less detailed. 

Federal Rule of Criminal Procedure 16 states, 

“ (G) Expert Witnesses. At the defendant's request, the government 

must give the defendant a written summary of any testimony that the 

government intends to use under Rules 702, 703, or 705 of 

the Federal Rules of Evidence during its case-in-chief at trial. If the 

government requests discovery under subdivision (b)(1)(C)(ii) and the 

defendant complies, the government must, at the defendant's request, 

give to the defendant a written summary of testimony that the 

government intends to use under Rules 702, 703, or 705 of 

the Federal Rules of Evidence as evidence at trial on the issue of the 

defendant's mental condition. The summary provided under this 

subparagraph must describe the witness's opinions, the bases and 

reasons for those opinions, and the witness's qualifications.”

ASTM E620 (which is referenced by both NFPA 921 and NFPA 1033) the 

Standard Practice for Reporting the Opinions of Technical Experts, applies to fire 

investigators. It provides guidance on logic and reasoning based 
32

methodology for the investigator for creating, critiquing, evaluating, 

supporting, and eliminating hypotheses. To meet the criteria for 

transparency, the source, scientific and technical basis, and the relationship 

of each hypothesis and criterion to known incident data is specified in 

addition to addressing the relative scientific or technical merits of alternate 

hypotheses supported and eliminated by the available data. Opinions or 

conclusions must account for all known relevant facts related to the 

incident and be consistent with accepted scientific and logical principles. 

[NFPA 921-17 at A.4.3.2]

Report preparation is one of the job performance requirements (JPRs) 

found in NFPA 1033. The NFPA 1033 requirement is similar to that 

expressed in ASTM E620. NFPA 1033 Section 4.7.1 states, “Prepare a 

written report, given investigative findings, documentation, and a specific 

audience, so that the report accurately reflects the investigative findings, is 

concise, expresses the investigator’s opinion, contains facts and data that 

the investigator relies on in rendering an opinion, contains the reasoning of 

the investigator by which each opinion was reached, and meets the needs 

or requirements of the intended audience(s).”

3-3 Level of Certainty

NFPA 921 in the chapter on Basic Methodology addresses the level of 

certainty, and it states, “The level of certainty describes how strongly 

someone holds an opinion (conclusion). Someone may hold any opinion to 

a higher or lower level of certainty. That level is determined by assessing 

the investigator’s confidence in the data, in the analysis of that data and 

testing of hypotheses formed. That level of certainty may determine the 

practical application of the opinion, especially in legal proceedings.”

NFPA 921 further states that many courts have set a threshold of certainty 

for the investigator to be able to render opinions in court such as “proven 

to an acceptable level of certainty,” “a reasonable degree of scientific and 

engineering certainty,” or “a reasonable degree of certainty within my 

profession.”
33

The National Commission on Forensic Science [NCFS 2016], on the other 

hand, has addressed the level of certainty that some lawyers and judges 

mistakenly believe is required for testimony. That is “a reasonable degree 

of scientific (or medical, or engineering, or discipline) certainty.” In fact, 

“scientific certainty” does not exist. It is a term of art coined by lawyers and 

is now falling into disrepute.

On March 22, 2016, the NCFS voted to recommend that the term 

“reasonable certainty,” whether couched as "scientific certainty'' or 

"[discipline] certainty”, should not be used. It recommended that the 

Attorney General direct all attorneys appearing on behalf of the DOJ (a) to 

forgo the use of these phrases unless directly required by judicial authority 

as a condition of admissibility of the witness’s opinion and (b) to assert the 

legal position that such terminology is not required and is indeed 

misleading. The second recommendation to the Attorney General states 

that the AG should direct all forensic science service providers and forensic 

science medical providers employed by the DOJ not to use such language 

in reports or to couch their testimony in such terms unless directed to do so 

by the judge. A final recommendation adopted by the NCFS is that the 

Attorney General should, in collaboration with NIST, urge the OSAC to 

develop appropriate language that may be used by experts when reporting 

or testifying about results or findings based on observations of evidence 

and the data derived from the evidence. [NCFS 2016]

The DOJ is continuing the process of developing guidance documents 

governing the testimony and reports of its forensic experts. These 

documents, which are being developed for each forensic science discipline, 

are known as “Uniform Language for Testimony and Reports,” or ULTR 

documents. The ULTRs are designed to provide guidance on the 

submission of scientific statements by the Department’s forensic examiners 

when drafting reports and testifying.

According to one legal scholar 

“The reasonable-degree-of-scientific-certainty language almost 

certainly was drafted by the lawyers. Scientists have no use for 

this phrase (outside the courtroom). Indeed, “a reasonable degree 
34

of scientific certainty” is not a defined concept in scientific 

disciplines or even in law. ... It is legal mumbo-jumbo derived 

from archaic cases in which lawyers discovered that if a medical 

doctor did not utter the incantation “to a reasonable degree of 

medical certainty,” his testimony might be excluded because 

doctors were not supposed to talk about mere probabilities.” 

[Kaye 2010]

The problem with testifying to a “reasonable degree of scientific certainty” 

is that a jury might equate it with certainty at the level of beyond a 

“reasonable” doubt.

The OSAC Subcommittee on Fire and Explosion Investigations urges fire 

investigators to follow the NCFS Recommendations and avoid the use of 

the term “reasonable degree of scientific [or discipline] certainty” unless 

the Court insists. The Subcommittee may address further limitations on 

testimony in the future.

3-4 The Impact of Daubert and NFPA 921 on Fire Investigation 

Testimony

The first edition of NFPA 921 was published just a year before the Daubert 

decision was handed down. The first appellate decision on the applicability 

of Daubert to fire investigation was handed down by the 11th Circuit in 1998 

in the case of Michigan Millers Mutual Insurance Corp. v. Jeanelle Benfield. 

This was an arson case from Sarasota Florida, wherein Michigan Millers 

filed a declaratory action in federal court seeking to void the contract of 

insurance because of arson and misrepresentation. Miller’s expert had his 

testimony excluded because according to the Court, 

“At trial, Millers’ fire causation expert tried to explain how he came 

to the conclusion that the fire in the Benfield home was intentionally 

set. Buckley stated at trial that he came to his opinion that the fire was 

intentionally set by eliminating all accidental causes, and by 

determining that, given that the fire began on the dining room table, 

there were no other possible sources of ignition of the fire. Essentially, 
35

the testimony of Buckley reveals that he came to his opinion that the 

fire was incendiary largely because he was unable to identify the 

source of the ignition of the fire. In determining that the fire was 

incendiary, Buckley performed no tests and took no samples. At trial, 

Buckley was unable to describe the chandelier that hung over the table 

and unable to explain the methodology by which he eliminated the 

chandelier as a possible ignition source for the fire. After telling the 

jury on direct that he believed someone poured lamp oil from the lamp 

oil bottle over the clothes and set the clothes ablaze, on crossexamination Buckley admitted that he did not know even if the lamp 

oil bottle had contained lamp oil before the fire and that there was no 

scientific basis for such an opinion. With such testimony as a 

backdrop, the district court granted the motion by Mrs. Benfield to 

strike the testimony of Buckley, finding that while Buckley held the 

opinion that the fire was intentionally set, he was unable to rationally 

explain how he came to that conclusion.”

The Appeals Court found that Buckley’s testimony was, in fact, scientific, 

and therefore subject to scrutiny under Daubert. The Court did not credit 

the amicus brief filed on behalf of the International Association of Arson 

Investigators (IAAI), which argued that because fire investigation was “less 

scientific” than the kind of testimony envisioned under Daubert, “An 

application of a strict Daubert analysis to a cause and origin investigation is 

improper.”

The 11th Circuit’s ruling had a curious effect on fire investigation. Because 

the Court held that a fire fighter’s testimony was admissible because he 

based his findings on “experience” instead of “science,” certain litigators 

began encouraging fire investigators to avoid the use of the word “science” 

in their reports and testimony. This ill-conceived advice became moot in 

1999 when the Supreme Court, ruling in the Kumho case (which also 

originated in the 11th Circuit) held that Daubert inquiries on reliability 

applied to all expert testimony, whether it was based on scientific, 

technical or other specialized knowledge. In its unanimous decision, the 

Supreme Court relieved trial court judges of deciding whether expert 

testimony was scientific. The trial judge’s gatekeeping task was to 

determine whether the proposed testimony was reliable.
36

After the Kumho decision, the IAAI and the fire investigation profession in 

general, realized that fire investigations should be conducted according to 

the precepts of science, but not before fighting one last battle. Although the 

Supreme Court had already made all fire investigator testimony subject to 

a reliability inquiry, more than a hundred comments were submitted to the 

NFPA for the 2001 edition of NFPA 921, protesting the Technical 

Committee’s decision to continue to recommend the use of the scientific 

method. Many arguments were made in support of a “systematic 

approach” instead of the scientific method. These arguments revealed a 

lack of understanding of what constitutes a scientific investigation. 

One change was made in the description of the scientific method, which 

the NFPA Technical Committee hoped would eliminate the contention that 

to “scientifically” test a hypothesis, one needed to rebuild the building and 

then burn it down again. In the paragraph on hypothesis testing, the 

following sentence was added: “This testing of the hypothesis may be 

either cognitive or experimental.” This statement explained the proposition 

that as long as deductive reasoning was used to test the hypothesis, a 

physical experiment was not a necessity. Some fire investigators took this 

as a license to merely think about the fire scene and rely on their 

experience, as they had in the past, but the subsequent edition of NFPA 

921, published in 2004, provided more details about the use of inductive 

and deductive reasoning.

It was in 2000 that the leadership of the IAAI endorsed the adoption of the 

next (2001) edition of NFPA 921. IAAI President Gerard Naylis said at the 

time that it was time for the IAAI to start looking out the windshield and 

stop looking at the rearview mirror. (It should be noted that the leadership 

of NAFI had endorsed NFPA 921 as the “standard of care” for fire 

investigation since the first edition.)

Also in 2000, the U. S. Department of Justice, NIJ issued a research report 

entitled Fire and Arson Scene Evidence: A Guide for Public Safety 

Personnel [NIJ 2000] , which contains the following statements about 

NFPA 921:
37

“In 1992, the National Fire Protection Association (NFPA) issued 

NFPA 921: Guide for Fire and Explosion Investigations, a consensus 

document reflecting the knowledge and experience of fire, engineering, 

legal, and investigative experts across the United States. This 

document is continuously reviewed, public proposals and comments 

are solicited, and a revised edition is produced every 3 to 5 years. It 

has become a benchmark for the training and expertise of everyone 

who purports to be an expert in the origin and cause determination of 

fires.

The investigator should recognize the limitations of his or her own 

expertise and determine what personnel may be required to process the 

scene according to NFPA 921 and other recognized national 

guidelines. If neither the origin nor the cause is immediately obvious, 

or if there is clear evidence of an incendiary cause, the investigator 

should conduct a scene examination in accordance with NFPA 921 

and other recognized national guidelines or seek someone with the 

expertise required.”

Over the next few years, trial courts began to recognize the authority of 

NFPA 921, excluding testimony if an investigator’s methodology deviated 

significantly from its guidance, and admitting it if the 921 methodology 

was followed [Lentini 2007]. Due to the deferential “abuse of discretion” 

standard for review of a trial court’s decisions on admissibility, most 

rulings on admissibility are not published, and sometimes not even 

written. A subscription decision reporting service called DaubertTracker 

(www.DaubertTracker.com) lists over 1,800 court decisions on Daubert

challenges to fire investigators, and most of these decisions reference NFPA 

921. Some frequently cited cases are discussed below.

Weisgram v. Marley Co. 528 U.S. 440 [2000]

This case arose out of a December 30, 1993 Fire in Fargo, ND that was fatal 

to Bonnie Weisgram, who died from smoke inhalation. Three experts 

attributed the cause of the fire to a 15-year-old electric baseboard heater 

manufactured by Marley. The expert testimony was admitted at trial, and 

the jury awarded $500,000 to Bonnie’s son Chad and $100,000 to State Farm 
38

insurance for their subrogated loss. Marley appealed the case to the Eighth 

Circuit, arguing that the experts’ testimony should have been excluded.

On February 23, 1999, the Eighth Circuit held that the District Court judge 

had abused his discretion by admitting the expert testimony and that he 

should have granted Marley a judgment as a matter of law. The Court 

examined both the qualifications and the methodology of the experts and 

applied the Supreme Court’s decision in GE v. Joiner.

The Eighth Circuit's decision was appealed to the Supreme Court, where it 

was upheld. The fire took place shortly after the Daubert decision was 

handed down, and the appeal took place after the Joiner decision set out the 

“abuse of discretion” standard for review. At the time of the Eighth 

Circuit's decision, the Kumho case was pending before the Supreme Court.

The experts were a Fire Chief, who the Eighth Circuit said had properly 

been allowed to testify about the origin of the fire but was improperly 

allowed to speculate as to the cause. A second expert, an electrical expert 

was excluded as merely speculating. His determination was based on 

“everything else being ruled out” by the Fire Chief. He had not visited the 

fire scene. He opined that after operating for 15 years without incident, 

both the thermostat and the high limit control suddenly and 

simultaneously did not function to shut the heater off. He was unable to 

get an exemplary heater from the same apartment building to similarly 

malfunction and testified that he had no idea what caused the thermostat 

to fail, and agreed that there were no design defects. The Eighth Circuit 

stated that the District Court abused its discretion by permitting him to 

testify as an expert witness regarding matters about which he could only 

speculate. 

The third expert was a metallurgist with no experience in heater design or 

contact design. He opined that because the contacts were serrated, they 

were badly designed, even though he did not know the heater wattage or 

what temperature it might attain.

In a finding that shows the inherent problems in allowing non-scientists to 

rule on scientific evidence, the Court found that in order to be defective, 
39

this heater would have had to sustain two simultaneous failures. It is clear 

that either the high limit thermostat or the operating thermostat could have 

failed years before the fire, and there was no requirement that the failures 

be simultaneous.

Truck Insurance Exchange v. Magnetek 360 F. 3d 1206 [2004]

This case arose out of a November 9, 1998 fire at Sammy's restaurant in 

Lakewood, Colorado. Upon their arrival, the fire department found only 

smoke, no fire, until the fire caused the kitchen floor to collapse, indicating 

a fire in the basement. There was a fluorescent light in the basement and 

according to the experts, no other potential ignition source. Thus, the light 

must have been the cause.

The ballast in the light, however, contained a thermal cut off (TCO) which 

still functioned after the fire and operated at 232 F. A similar ballast, when 

shorted, reached a stable temperature of 300 F.

There is a never-proven hypothesis that, upon continued exposure to a heat 

source below its ignition temperature, the ignition temperature of wood 

can be lowered to a point where a heat source of only 200 F might ignite it. 

This was the plaintiff's case against Magnetek. 

The trial court agreed with Magnetek when it moved for summary 

judgment and the exclusion of the plaintiff’s electrical engineer. Truck 

appealed to the 10th Circuit but lost. In this case, the 10th Circuit ruled that 

the theory of pyrophoric carbon had never been demonstrated in the 

laboratory, so it was not admissible as evidence. Unfortunately, the court 

adopted some incorrect terminology and ended up stating that pyrolysis, a 

necessary phenomenon that precedes the combustion of wood, did not 

occur.

Acknowledging the terminology problem, the Court held, “We note that 

there appears to be some confusion among the parties, the District Court, 

and even the scientific community as to the proper terminology for the 

theory of long-term low-temperature and the charring it involves. This 

court is not in a position to decide such questions for the scientific 
40

community, but for this opinion, we will refer to this process as ‘pyrolysis.’ 

To the extent that we use the term ‘pyrophoric carbon,’ we are talking 

about the substance charred wood.” They further held that the District 

Court did not abuse its discretion when it ruled that under the Daubert 

trilogy, pyrolysis was not yet a scientifically reliable theory upon which to 

base an expert opinion about the cause of the Sammy’s fire. This case again 

illustrates that courts are not in a position to decide scientific questions. In 

its conclusion, the 10th Circuit noted that the theory of long-term, lowtemperature ignition of wood was interesting, and one which may 

eventually be sufficiently tested and researched to serve as the basis for an 

expert opinion under Rule 702. However, the Court was clear in its opinion 

that the theory has yet to reach that point and that, as a consequence, 

expert opinions based on the theory should be carefully scrutinized.

Bryte v. American Household, Inc. Fourth Circuit No. 04-1051

Lova Bryte, a paralyzed stroke victim from West Virginia, died in an 

October 3, 2000 fire while sitting in her chair, and a state fire marshal 

opined that the ignition source was an electric blanket. The trial court 

excluded the fire marshal’s testimony because he had failed to examine, 

consider and eliminate other potential causes of the fire in the area of the 

blanket, which included other electrical devices and a candle. The Fourth 

Circuit Court of Appeals held that the District Court did not abuse its 

discretion in excluding the testimony, describing the record as “so 

speculative that a jury has to guess to determine whether there is liability 

of either the warranty or negligence for the jury to speculate on.”

The court found that the fire marshal's opinion was reached in 

contravention of NFPA 921's guidance that “all other reasonable origins 

and causes be excluded.”

Carr v. Georgia [1997] Ga. LEXIS 104. 

This case arose out of an April 7, 1993 fire, in which Mr. Carr was convicted 

of setting a fire in order to kill his wife. The case had many interesting 
41

aspects, but Mr. Carr's conviction was overturned based on the admission 

of evidence of 12 unconfirmed accelerant detection canine (ADC) alerts.15

It was the Carr case that prompted the introduction of a tentative interim 

amendment (TIA) to NFPA 921 in 1996.16 The tentative interim amendment 

was adopted in 1997, and the Georgia Supreme Court took note of the 

change to NFPA 921 in its deliberations. In its decision, the Georgia 

Supreme Court wrote, 

“While the use of trained dogs can be a valuable part of investigative 

procedures and can provide important elements of probable cause to 

search ... , dog alerts to accelerants have not been shown, either at the 

trial of this case nor in any Georgia appellate decision, to have the 

scientific reliability necessary to permit their use as substantive

evidence of the presence of accelerants. The trial court's ruling to the 

contrary was error. The State argues that the admission of the 

evidence, if error, was harmless in light of other evidence of the 

presence of an accelerant. However, there was no other direct evidence 

of the presence of an accelerant, and thus, no direct evidence of 

arson.”

Wisconsin v. Joseph Awe, Marquette County Case No. 07 CF 54

This is another case where changes to NFPA 921 persuaded the court to 

overturn a conviction. A fire occurred on September 11, 2006, at Mr. Awe’s 

place of business, JJ’s Pub. Investigators for the state and his insurance 

company, working together, concluded that the fire was intentionally set 

15 The term “Accelerant Detection Canine” has been updated to the more neutral 

“Ignitable Liquid Detection Canine,” abbreviated as IGL Canine.

16 A TIA is an emergency change to an NFPA document that can only occur when waiting 

until the next scheduled edition would cause irreparable harm. In this case, there was a 

body of law forming around unconfirmed canine alerts, and the Technical Committee on 

Fire Investigations persuaded the NFPA Standards Council that waiting until 1998 would 

only encourage more admissions of unreliable evidence.
42

based admittedly on the application of “negative corpus” methodology. 17

They could find no potential accidental sources of ignition at their 

hypothetical origin.

Unfortunately, the origin determined by these investigators was incorrect. 

Across the room, there was a pattern very similar to the fire pattern at the 

alleged origin, but this pattern had an ignition source associated with it. 

There was an electric service distribution panel with its cover removed, 

and that exhibited clear signs of malfunction. That evidence eluded both 

the insurance company’s and the defendant’s electrical engineers.

Between the time Mr. Awe was convicted in 2007 and the time his appeal 

was heard by the trial court, NFPA 921 had been changed to disparage the 

use of “negative corpus” methodology. The judge found that this change in 

NFPA 921 constituted “new evidence,” and ordered a new trial as a result. 

In his ruling, the judge wrote, “This is not the fault of the State's arson 

investigators, who were trained in the flawed methodology. It is the result 

of the maturation of the arson investigation field, a gradual process of 

taking a second look at the negative corpus thinking.” Mr. Awe was freed 

shortly after that when the state agreed that without resorting to negative 

corpus thinking, it could not prove that the fire was intentionally set.

After his release, Mr. Awe went on to sue both his insurance carrier and the 

electrical engineer that the insurance carrier had retained and was 

successful in both actions.

Other Daubert Challenges

There have been several review articles published on the effects of Daubert 

and its progeny (the Joiner and Kumho cases) on fire investigation 

testimony. Sufficient cases have been decided that the case law may be said 

17 NFPA 921-21 at 19.6.5 describes negative corpus methodology as follows: 

“Identifying the ignition source for a fire by believing to have eliminated all ignition 

sources found, known, or suspected to have been present in the area of origin, and for 

which no supporting evidence exists, is referred to by some investigators as negative 

corpus. “
43

to be settled (no longer subject to change), and so most of these articles are 

a decade or more old. In 2006, Rauschwerger and colleagues published 

“The Big Daubert Hurdles in Fire & Explosion Litigation,” which lists 

several instructive cases. [Rauschwager et al. 2006]

3-5 The Impact of NFPA 1033 on Fire Investigation Testimony

NFPA 921 has seen a long history of use by attorneys attempting to 

challenge the methodology of fire investigators. Fire investigators who 

wish to avoid being challenged with NFPA 921 have traditionally taken 

coverage in the fact that NFPA 921 is “only a guide.” This is not a very 

effective means of avoiding cross-examination, because the question “Why 

did you not follow the standard?” simply becomes “Why did you not 

follow the guide?”

NFPA 1033 has not been used nearly as often in litigation as NFPA 921, 

and there is no record of an investigator being excluded for failing to 

adhere to it, but it has received some mention. In McCoy v. Whirlpool, a case 

that describes NFPA 921 as “the gold standard,” the defense expert was 

challenged because he failed to cite NFPA 1033 in his report. The court 

found that this failure was not sufficient to exclude the expert because it 

found that the expert was eminently qualified. Plaintiffs argued that NFPA 

1033 was so basic, that the expert’s failure to mention it showed him to be 

unqualified, while defendants argued that NFPA 1033 was so basic that it 

is obvious that the expert would follow it, and there was no need to 

mention it. The court said that the failure to cite NFPA 1033 was not 

disqualifying, but it could be used on cross-examination. [McCoy v. 

Whirlpool 2003]

In another case involving Whirlpool, the defendant sought to exclude the 

plaintiff’s expert because he had never designed a refrigerator. The court 

denied the motion and in addressing the qualifications issue noted that the 

expert was qualified under NFPA 1033. [Thompson v. Whirlpool 2008]

In another case, NFPA 1033 was cited in the expert’s resume, leading the 

court to believe that in addition to following proper methodology, he was 
44

“qualified as an expert given his 15 years of experience in numerous 

training classes, citing, among other things, fire and explosion 

investigations utilizing NFPA 1033 and 921.”[Young v. Allstate 2010]

Changes in the 2009 edition of NFPA 1033 have made it a much more 

useful tool for challenging fire investigators. It is a short document with 

mandatory requirements, and the addition in 2009 of a list of subjects on 

which the fire investigator is required to have knowledge beyond the high 

school level has made challenging fire investigators a straightforward 

exercise by asking a question such as: “What are the basic units of energy?” 

“What are the basic units of power?” “What is the difference between 

energy and power?”

Investigators who are unable to answer this type of question may have a 

difficult time persuading the court that they are qualified according to 

NFPA 1033 but failing to answer these questions correctly tends to shortcircuit the process. Instead of trying to convince a judge that one is qualified 

despite the lack of mandatory knowledge, the task becomes trying to 

convince a sponsoring attorney that one is qualified. Challenges to experts 

who are unable to answer basic questions about fire chemistry and fire 

dynamics need not go as far as court if the sponsoring attorney decides not 

to use the expert. For this reason, cases, where the expert has demonstrated 

a lack of knowledge, tend to be settled or dismissed. [Reis, 2015]

The following is an excerpt of a motion challenging a witness who 

“flunked” a basic NFPA 1033 quiz at his deposition. This motion in limine 

was filed in a subrogation case in which the Plaintiffs alleged the negligent 

installation of a water heater.

“[Witness] is Plaintiff's origin and cause expert and his testimony is 

the cornerstone of Plaintiff's theory of causation of the fire. However, 

his testimony establishes that he lacks the basic knowledge to conduct 

a reliable fire scene investigation and his opinions are unreliable. ... 

[Witness] testified that (1) he did not know the difference between 

energy and power; (2) he could not identify the basic units of power; 

(3) he could not define energy release rate; (4) he could not tell how 

heat release rate was measured; (5) he could not define the term 
45

"watt"; and (6) he did not know the maximum heat flux in the fire. 

[Witness] could not define the term “fire chemistry.” [Witness] could 

not explain the difference between a vapor and a gas. [Witness] 

testified that he did not know whether the tankless water heaters in 

question were fueled by natural gas or propane and he does not know 

the chemical formula of propane, the volume of oxygen it takes to react 

with one volume of propane and that he had not taken any classes in 

thermometry. [Witness] testified that NFPA 1033 applied to his fire 

scene investigation. [Witness] acknowledged that NFPA 1033 lists 16 

topics that fire investigators should have knowledge of beyond the 

high school level. He could not name any of the 16 topics.”

While NFPA 921 is, in fact, a guide, NFPA 1033, which is a mandatory 

standard, cites to NFPA 921 as the source of the knowledge an investigator 

is required to possess, thus making a bridge between the two documents. 

[Hewitt and McKenna 2014] Challenges to expert qualifications as opposed 

to methodology are likely to become more common, although because of 

cases settling, there may not be a substantial body of law as a result.

3-6 Conclusion 

NFPA 921 has become so entrenched in the post-Daubert world of fire 

litigation that fire investigators are obliged to at least testify that they 

followed it or be able to articulate why they deviated from its guidance. 

Although the first two decades of Daubert challenges relied on NFPA 921, 

more direct “Rule 702” challenges of the investigator’s qualifications based 

on NFPA 1033 are likely to become more common. This should result in a 

more careful vetting of fire investigators proposing to give expert 

testimony, and an overall improvement in the quality of evidence 

presented to courts and juries. 

REFERENCES

Hewitt, TD and McKenna WJ, (2014) A Perfect Storm Brewing for Fire 

Investigators in Court.
46

http://ssrn.com/abstract=2381519

David H. Kaye, (2010), The Double Helix And The Law Of Evidence, Harvard 

University Press.

Lentini, J. (2007) “The Standard of Care in Fire Investigation.” Canadian 

Association of Fire Investigators. 

https://drive.google.com/drive/folders/1d_V2v8q8fkWAmsxCD3icf6QiLYziR47

McCoy v. Whirlpool Corp., District of Kansas; 2003 U.S. Dist. LEXIS 6901. 

http://www.leagle.com/decision/20051566379FSupp2d1187_11457/McC

OY%20v.%20WHIRLPOOL%20CORP.

Morgenstern, M., (2020) Daubert v. Frye-A State-by-State Comparison. 

https://www.theexpertinstitute.com/author/morgenstern/

NIJ (2000), Fire and Arson Scene Evidence: A Guide for Public Safety 

Personnel, Office of Justice Programs

https://www.ojp.gov/pdffiles1/nij/181584.pdf

NCFS, Recommendations to the Attorney General Regarding Use of the 

Term “Reasonable Scientific Certainty” March 3, 2016. 

https://www.justice.gov/ncfs/file/839726/download

NFPA 921 (2017): Guide for Fire and Explosion Investigations, NFPA, Quincy, 

MA. http://www.nfpa.org/codes-and-standards/all-codes-andstandards/list-of-codes-and-standards?mode=code&code=921

NFPA 921, Fall 2000 Meeting, Report on Comments, NFPA, Quincy, MA, 

2000, 437. 

http://www.nfpa.org/Assets/files/AboutTheCodes/921/ROCF2000-

921.pdf

Rauschwager, et al., (2006) “The Big Daubert Hurdles in Fire & Explosion 

Litigation,” The Subrogator, NASP. 
47

https://www.martindale.com/products-liability-law/article_ClausenMiller-PC_247060.htm

Reis, J., (2015) “Expert Challenges and the Revised NFPA 1033,” Fire and 

Arson Investigator, July 2015. 

https://s3.amazonaws.com/v3-

app_crowdc/assets/1/15/15b42140544b5aa1/1033_Challenges_by_Reis_J

uly_2015_FAI.original.1458932668.pdf

Risinger, D. M., (2000) “Navigating Expert Reliability: Are Criminal 

Standards of Certainty Being Left on the Dock?” 64 ALB. L. REV. 99, 101, 

104. 

https://papers.ssrn.com/sol3/papers.cfm?abstract_id=251033.

Thompson v. Whirlpool Corp., (2008) U. S. Dist. Lexus 38968 (W. D. Wash. 

May 13, 2008.)

Young v. Allstate Insurance Company, (2010) U. S. District Lexus 14514 (E. D. 

Mo., February 19, 2010).
48

4. THE PRINCIPLES OF SCIENCE AND 

INTERPRETING SCIENTIFIC DATA

4-1 The Scientific Method

The application of formal methodologies to the investigation of scientific 

phenomena has a long history. A recognition of this history and its 

application to fire phenomena is of particular importance to understanding 

the scientific nature of fire investigation.

In the days of Aristotle, argument was the method used to “find truth”. 

As methods of observation and data gathering advanced, the use of 

argument was recognized as not being a reliable method for coming to 

science-based conclusions. In 1620, a work by Francis Bacon, The New 

System, described a new process of inquiry, in which he wrote, 

“Argumentation cannot suffice for the discovery of new work since the 

subtlety of nature is greater many times than the subtlety of argument” 

[Sagan 1995]. Widely used since the 17th century, this “scientific method” 

broadly involves systematic observation and data collection, possibly 

including measurement and experimentation, leading to the formulation, 

testing, and modification of hypotheses.

The application of science to fire has its roots in the Christmas lectures of 

Michael Faraday to the Royal Institute in London beginning in 1848. The 

Chemical History of a Candle was the title of a series of six lectures given by 

Faraday for young people. The lectures examined the chemistry and 

physics of flames. Through careful observation and analysis, Faraday was 

able to develop an understanding of fire phenomena and then present that 

understanding in his lectures using several demonstrations [Faraday 1861]. 

The scientific method is a process of inquiry and analysis. It is a way of 

thinking. It is a set of techniques for testing the validity of ideas. In its most 

basic form, we all learned and practiced this method in high school science 

class. Indeed, children now learn the scientific method in elementary 

school.
49

4-2 Fire Investigation – Basic Methodology

Fire dynamics is a term commonly used to define the study of fire 

behavior. While fire dynamics research was rapidly developing in the 

1970s and 1980s, little, if any, of that research, was being used by fire 

investigators. Many fire investigators of that time refused to think of 

themselves as a scientist; thinking that still exists to some extent today. 

There were, however, those who recognized the need to conduct fire 

investigations more scientifically. 

In 1985, a group of people was convened by the National Fire Protection 

Association and charged with developing a document to assist those 

involved in fire investigations. After seven years of development by a 

thirty-member committee (the NFPA 921 Technical Committee) 

representing the broad interests involved in fire investigation, NFPA 921 

was published. In 1992, this consensus document turned the fire 

investigation community on its head by stating that fire investigation was, 

at least in part, a scientific endeavor [NFPA 2021].18 Since that first edition 

in 1992, NFPA 921 has contained a chapter titled Basic Methodology.

In each of the nine editions since 1992 (the 2021 edition is the most recently 

released), the Basic Methodology chapter has articulated the need for a 

systematic approach to fire investigation. The systematic approach 

recommended by NFPA 921 is “based on the scientific method, which is 

used in the physical sciences.” NFPA 921 goes on to say that the scientific 

method “is a principle of inquiry that forms the basis for legitimate 

scientific and engineering processes, including fire incident investigation.” 

(emphasis added). NFPA 921 expands this recommendation by outlining 

the steps involved in the scientific method and detailing how those steps 

are applied to a fire investigation.

18 The 1992 through 1998 editions of NFPA 921 described fire investigation as “complex 

endeavor involving both art and science.” From 2001 onward, the description was 

changed to “a complex endeavor involving skill, technology, knowledge and science.”
50

While the membership of the NFPA 921 Technical Committee has changed 

through the ten editions, the description of the scientific method applied to 

fire investigation has remained a core part of the document since the first 

edition in 1992. To assist the reader of NFPA 921 in understanding this 

method, Figure 4.1 has been used to depict this methodology visually since 

the 1998 edition.

Figure 4.1 Diagram of the Scientific Method from NFPA 921 

(copyrightrequests@nfpa.org) 

Applied to fire investigation, recognizing the need involves recognizing the 

fact that a fire has occurred and that there is a desire to prevent similar fires 

in the future. How this “problem” can be solved is to conduct a proper fire 

investigation. In the most basic sense, fire investigation is a two-step 

process. An investigator first determines the location where the fire started 

– the origin. Then the investigator determines how the fire started – the 

cause. 

NFPA 921 makes clear that this scientific method is iterative. The 

hypothesis testing process must be continued until all realistic hypotheses 

have been tested. 
51

There may be numerous hypotheses developed concerning any individual 

fire incident. Several different investigators will often be involved in 

developing hypotheses for a particular investigation. This is a function of 

the investigators’ training, experience and expertise as well as their role in 

the investigation. The hypotheses developed, and how they relate to the 

incident, may be formed to explain such issues as origin, ignition sequence, 

fire cause or causes, issues related to damages and casualties, the 

functioning of fire detection and suppression systems, and the performance 

of building systems.

It is important for investigators to consider all feasible alternate 

hypotheses. Consideration of alternate hypotheses, without regard to the 

initial assessment of likelihood, will help the investigator to reduce the 

impact of cognitive biases. These biases can never be eliminated, even if the 

investigator is consciously aware of their existence [Heuer 1999].

4-3 Origin Determination

Origin determination is generally the first step in a fire investigation. A fire 

investigator should begin with the presumption that the origin is 

undetermined. If the fire is in a building, for example, anywhere in the 

entire building could have been the origin. The investigator then utilizes a 

process that involves identifying the physical location where the fire 

started and narrowing that location to the smallest area possible. In many 

fire events, the “room of origin” is determinable with relative certainty. If 

the fire destroys the entire building, the smallest area determinable may be 

the building. The “point of origin” is the smallest area. It is that spot where 

the fuel and heat source come together in such a way that a fire began. The 

size of the area of origin that can be determined will vary based on the 

specifics of the incident and the data available for collection. Narrowing the 

area of origin to a “point of origin” may not be possible.

Figure 4.2 shows the scientific method as applied to fire origin 

determination and includes elements of each step that should be 

considered by the fire investigator.
52

Figure 4.2 – The Scientific Method applied to the question of origin 

determination 

The process of determining the origin first involves the collection of originspecific data. Pre-fire conditions, the reconstruction of fuel packages, and 

the understanding of the ventilation conditions are key pieces of data. Once 

that information has been established, the investigator then analyzes the 

patterns created by the fire and develops hypotheses about the growth and 

spread of the fire. By understanding how the fire grew, the investigator can 

develop hypotheses as to where the fire started. 
53

Fire investigators determine the origin from interviewing witnesses, 

examining the scene, and putting that data into context with data that they 

collect from other sources. For example, the investigators will try to obtain 

data about where the fire was observed when it was still small. They will 

try to collect data from witnesses who had knowledge about the scene and 

what activities were taking place. 

While non-scene data is important, the data gained from the examination 

of the scene is usually essential to determine the origin. Some examples of 

data that are only available at the scene are: patterns of damage, the status 

of windows and doors, actual dimensions of the structure, arcing damage 

on electrical wiring, positions of valves and switches, and fire debris 

samples that can be used for laboratory examinations. 

The procedure recommended for scene examinations in NFPA 921 is to 

start the scene examination from areas of less damage and progress 

towards areas with the most damage. This practice of progressing from the 

least to the most damage is part of a systematic approach and is not 

because the area of most damage is the fire origin. There are many reasons 

why an area could have more damage than the origin, such as there was 

more fuel at that location, there was better ventilation at that location, or 

perhaps the fire department concentrated suppression efforts somewhere 

else.

As investigators are performing the scene examination, they consider each 

area and use their knowledge of fire science to determine whether a fire 

that started in that location could have spread to the other areas that 

sustained fire damage, or if the damage in that area could have been 

created by a fire starting somewhere else. To perform this assessment, 

investigators need to collect information about the building geometry and 

construction materials as well as information about the location of building 

contents and flammable items. Investigators use fire dynamics principles to 

evaluate fire flows, temperatures, the potential for full room involvement, 

and other technical knowledge to determine whether each area is a 

potential origin location. Investigators identify each of these potential 

origin locations and continue the scene examination to find other potential 

origin locations.
54

Recent training exercises and research have revealed that origin 

determination becomes more difficult if a room has been fully involved in 

fire for more than a few minutes [Carman 2008, 2010, Tinsley & Gorbett 

2012, Cox 2013 Gorbett et al. 2015]. Sometimes the best result that a fire 

investigator can achieve is identifying the compartment where the fire 

started.

4-4 Cause Determination

At the outset of an investigation, the cause is undetermined. If the origin 

remains undetermined, the cause will, in most cases, also remain 

undetermined. Assuming the origin determination is correct, the cause 

must lie within the area of origin, unless it has been removed. A large area 

of origin may encompass numerous potential ignition sources and fuels. A 

smaller area of origin is likely to encompass fewer. It is at the “point of 

origin” where a single competent ignition source and first fuel ignited 

combination is found. 

Cause determination involves the process of identifying the possible 

ignition sources and fuels in the determined area of origin. Once those 

have been identified, an analysis is conducted to analyze how the fire may 

have initiated - the circumstances and conditions that allowed the ignition 

source and fuel to come together. This usually requires the investigators to 

evaluate information from the fire scene examination as well as the “nonscene data.”

Figure 4.3 shows the scientific method as applied to fire cause 

determination and includes elements of each step that should be 

considered by the fire investigator.
55

Figure 4.3 – The Scientific Method applied to the question of cause determination 

Fire cause is defined as the circumstances, conditions, or agencies that 

bring a fuel, ignition source, and oxidizer (such as air or oxygen) together 

resulting in a fire or a combustion explosion [NFPA 2021]. Investigators 

must identify both the ignition source and the first fuel ignited to define 

the fire cause. The investigators must also identify how the ignition source 

was able to cause ignition of the fuel. For example, when an investigator 

identifies a book of matches as the ignition source and newspaper as the 
56

first fuel, they must also show, using data, how the matches ignited the 

newspaper.

Investigators then evaluate whether each of the potential ignition sources 

could be the actual fire cause. This can be a difficult and time-consuming 

process, involving a pairwise comparison of potential ignition sources with 

potential first fuels. The fire investigator must consider for each pair 

whether the proposed ignition source is competent to ignite the proposed 

first fuel, whether it was close enough and whether there is evidence that 

such ignition occurred. To perform this evaluation, the investigators use 

their knowledge and collected data as well as the input from other experts. 

For example, if a potential fire cause was an electrical appliance, the 

investigator may require input from an appliance expert. The 

considerations used in determining the ignition source and first fuel should 

be documented in writing. 

The accuracy of fire cause determination is dependent on the investigators 

identifying the correct origin of the fire. If the investigators are searching 

for ignition sources in the wrong location, they will not be able to 

determine the cause of the fire accurately. If the wrong area of origin is 

determined, the investigators could identify the wrong fire cause or decide 

that they could not find the fire cause. 

Throughout the process of cause determination, investigators are following 

the scientific method. As they are receiving additional information, they 

are constantly evaluating their hypotheses against the available data. If the 

hypothesis about the fire cause does not fit with the available data, the 

investigator must continue to evaluate other possible fire causes and if 

none are found to look for fire causes and to reevaluate whether the correct 

origin location was identified.

NFPA 921 makes clear that fuel by itself or an ignition source by itself does 

not create a fire. It is the action of the ignition source on the first material 

ignited that causes the fire. As outlined in the flow chart, a proper cause 

hypothesis must be developed from an understanding of the science 

behind the interaction between the heat and the fuel. Fire investigators 

need to understand this interaction.
57

4-5 Cause Classification

Once the investigators have determined the fire cause, NFPA 921, through 

the 2017 edition, provided guidance for the classification of the fire cause. 

The four fire cause classifications were undetermined, natural, accidental, 

or incendiary. Determining the cause and the classification of the fire cause 

are separate processes. Classification of the fire cause is used for 

assignment of responsibility, for statistical purposes, and reporting 

purposes. There is no requirement in NFPA 921 to classify the fire cause. 

The OSAC Fire and Explosion Investigation Subcommittee proposed the 

elimination of the cause classification chapter in NFPA 921 for the 2021 

edition revision cycle. The four fire cause classifications are inconsistent 

with the existing National Fire Incident Reporting System (NFIRS) cause 

classifications, and the process of classification adds nothing to the process 

of assignment of responsibility. The Technical Committee accepted the 

OSAC Subcommittee’s suggestion that the chapter on Cause Classification 

be eliminated.

4-6 Hypothesis Development

The NFPA 921 Technical Committee has included clear statements about 

what constitutes valid hypotheses. The following statements exhibit the 

Committee’s position on the development and testing of hypotheses.

“These hypotheses should be based solely on the empirical data that the 

investigator has collected through observation and then developed into 

explanations for the event, which are based upon the investigator's 

knowledge, training, experience, and expertise.”

“The investigator does not have a valid or reliable conclusion unless the 

hypothesis can stand the test of careful and serious challenge.”

“If the hypothesis is refuted or not supported, it should be discarded, and 

alternate hypotheses should be developed and tested.”
58

“The testing process needs to be continued until all feasible hypotheses have 

been tested, and one is determined to be uniquely consistent with the facts 

and with the principles of science.”[emphasis added]

“Any hypothesis that is incapable of being tested either physically or 

analytically is an invalid hypothesis. A hypothesis developed based on the 

absence of data is an example of a hypothesis that is incapable of being tested. 

The inability to refute a hypothesis does not mean that the hypothesis is 

true.”

“If no hypothesis can withstand an examination by deductive reasoning, the 

issue should be considered undetermined.” 

This last statement is particularly telling of the process of fire investigation. 

Given the destructive nature of fire and the effects of extinguishing the fire, 

data is lost or destroyed. In many cases, pieces of the puzzle cannot be 

found. If enough of those pieces of the puzzle are missing, a specific origin 

and cause of the fire may be indeterminable. An origin and a cause may be 

undetermined if no hypothesis can be sustained. The origin and cause may 

also be undetermined if multiple hypotheses can be reached based on the 

data analyzed. 

4-7 Reliability and Validity

There has been much discussion in the forensic science community about 

the reliability and validity of methods or procedures. Some of this 

discussion comes about because the terms have different meanings to 

different groups of forensic investigators. Consideration also needs to be 

given to whether it is the data itself or the conclusions from the data that is 

the focus.

Many forensic endeavors involve laboratory analysis. In these applications, 

reliability means repeatability or reproducibility of measurements or 

conclusions, while validity refers to the accuracy of the measurements or 

conclusions. In non-laboratory settings, conclusions are rendered based on 
59

data, informed by an investigator’s experience and training. While it is 

possible to assess the reliability of such judgments by assessing intra- and 

inter-investigator agreement, validity is much more difficult to evaluate. 

Issues of reliability and validity enter the field of fire investigation in 

several ways. One is in the collection of facts and data. The reliability of 

data, particularly things like the observations of witnesses, need to be 

considered in any investigation. Given the nature of fire and explosion 

events, data is often destroyed or lost due to the event itself or because of 

the efforts of first responders. The reliability and “value” of the data needs 

to be considered. When the data gathered is inconsistent, the investigator 

must report the inconsistency and resolve if scientifically justified.

Additionally, following the scientific method, hypotheses must be testable. 

A hypothesis that is based on the absence of data cannot be tested and 

should be discarded. Additionally, the investigator must understand the 

difference between evidence of absence and absence of evidence. Just 

because there is “no evidence” to disprove a hypothesis, does not mean 

that the hypothesis is supported.

Conclusions drawn by investigators are based on the analysis of data —

incorrect analysis results in incorrect conclusions. The vast majority of fire 

investigators base opinions about the origin of a fire or explosion on the 

interpretation of patterns—the resultant damage or lack of damage caused 

by the event. In a small well-contained fire, these patterns typically are 

easily discernible, and their analysis is, for the most part, straightforward. 

As the damage from the event increases, the interpretation of patterns is 

much less straightforward. Initial patterns can be obscured, new patterns 

can be created in areas away from the origin, and patterns can be destroyed 

by the fire or firefighting operations, all of which make the analysis and 

interpretation of patterns more difficult and potentially unreliable.

Validity issues also come about due to the training and experience of the 

investigator. The application of complex scientific principles, based on 

physics and chemistry, is often made by investigators with little or no 

training in these disciplines, which can lead to errors.
60

The measure of whether expert opinion testimony is allowed by some 

courts considers reliability and validity as part of the evaluation. Rule 702 

of the Federal Rules of Evidence requires judges to evaluate, in part, the 

following when admitting expert testimony:

● the testimony is based upon sufficient facts or data,

● the testimony is the product of reliable principles and methods, and 

● the witness has applied the principles and methods reliably to the 

facts of the case.

There is little in the way of procedures outlining how a fire investigator 

evaluates data. More procedures need to be developed and researched (see 

Chapter 7). As one example, much of a typical origin investigation relies on 

the interpretation of patterns left by the fire. A scientific study [Gorbett et 

al. 2017] has shown that a defined procedure to identify origin 

determination based on fire patterns increases reliability and validity. 

4-8 Uncertainty and Error

Scientific data and processes (as well as nonscientific evidence) are subject 

to a variety of sources of error. A key task for fire investigators 

conducting a scientific study is to identify as many sources of error as 

possible, to control or to eliminate as many as possible, and to estimate the 

magnitude of remaining errors so that the conclusions drawn from the 

study can be evaluated. 

Misinterpreting data, such as how a particular pattern was created, may 

lead to error in an origin determination. Failure to consider the heat energy 

required to raise a fuel to its ignition temperature may lead to error in a 

cause determination. Failing to resolve inconsistent data will also likely 

result in an error. 

In the fire investigation community, the issues of error are often not 

evaluated until a case is litigated. Challenge occurs most often in this 

setting. There is a need for error to be identified and corrected in all fire 

investigations. Most of this country’s fire codes evolve based on the lessons 
61

learned from fires. Incorrect conclusions drawn have the potential to cause 

inappropriate requirements in codes and standards.

In articulating opinions, it is incumbent upon the investigator to eliminate 

error to the extent possible and to clearly articulate any uncertainty.

4-9 Conclusions

Fire and explosion investigation must be recognized as a scientific 

endeavor and practiced as such. This should involve requiring 

investigators to articulate their scientific reasoning. It should also involve 

requiring investigators to enumerate the possible origin and cause 

hypotheses that were developed and showing how particular hypotheses 

were eliminated until a hypothesis that is uniquely consistent with the 

facts and the principles of science was reached. Requiring rigorous, 

independent review other than through the adversarial process of the 

courts is one method of assuring technically sound decisions in those 

investigations with the highest consequences. 

REFERENCES

Faraday, Michael (1861). W. Crookes, ed. A Course of Six Lectures on the 

Chemical History of a Candle. Griffin, Bohn & Co. ISBN 1-4255-1974-1.

https://archive.org/details/chemicalhistoryo00faraiala

Federal Rules of Evidence, Rule 702, 

https://www.law.cornell.edu/rules/fre/rule_702

Gorbett G, Meacham B, Wood C, Dembsey N (2017) Structure and 

Evaluation of the Process for Origin Determination in Compartment Fires, 

Fire Technology 53:301. 

https://doi.org/10.1007/s10694-015-0553-3

Heuer, R., (1999) Psychology of Intelligence Analysis, Center for the Study 

of Intelligence, U.S. Central Intelligence Agency, 1999, 
62

https://www.cia.gov/static/9a5f1162fd0932c29bfed1c030edf4ae/Pyscholo

gy-of-Intelligence-Analysis.pdf

NFPA (2021), NFPA 921, Guide for Fire and Explosion Investigations, 

NFPA, Quincy, MA.

http://www.nfpa.org/codes-and-standards/all-codes-and-standards/listof-codes-and-standards?mode=code&code=921

Sagan, C (1997) The Demon-Haunted World: Science as a candle in the 

dark. Ballantine Books. 

http://www.metaphysicspirit.com/books/The%20DemonHaunted%20World.pdf
63

5. DESCRIPTIONS OF SOME FIRE AND

EXPLOSION INVESTIGATION DISCIPLINES

This chapter describes the techniques and processes used during a typical 

fire investigation. It is organized according to the Job Performance 

Requirements (JPR’s) as laid out in NFPA 1033, Standard for Professional 

Qualifications for Fire Investigator:

1. Scene Examination

2. Documenting the Scene

3. Evidence Collection/Preservation

4. Interviews

5. Post-Incident Investigation (non-scene)

6. Presentations (written and verbal reports, testimony)

This description is focused on the current state of fire investigation as it is 

practiced today and identifies some deficiencies in those practices or 

referenced guides and standards.

5-1 Scene Examination

The fire scene is examined to understand the condition of the property 

before the fire and the effects of the fire upon the property. The scene data 

collected is in support of determining the origin and development of the 

fire as well as the cause of the fire.

Fire scenes are generally observed from the perimeter to gain a global view 

of the damage and assess the extent of the fire-damaged area that will 

require interior examination. The perimeter survey also generally allows an 

initial assessment of the safety issues at the scene and the need for 

perimeter controls. After these initial surveys, a more detailed examination 

of fire effects is undertaken.
64

The patterns of fire effects are key observations that can be analyzed to 

determine the origin and spread of the fire. The fire effects that create the 

damage patterns include:

1. Loss of mass

2. Charring

3. Spalling

4. Oxidation

5. Melting and alloying

6. Thermal expansion and deformation

7. Smoke deposition

8. Clean burn

9. Calcination

10. Glass breaking and deformation

11.Victim Injuries

12. Electrical arc melting

These fire effects are the result of thermal insults ranging from merely hot 

gases to direct flame contact. Understanding the fire effects upon the wide 

range of materials present in the built environment is key to understanding 

the fire exposure that creates fire effects and the development of the fire. As 

is apparent from the list of fire effects above, there is a wide range of 

potential fire effects and the nature of these fire effects is directly 

determined by the chemical and physical nature of each of the materials 

present.

Field methods for determining fire effects and their patterns include 

visual/photography, and depth measurements (char and calcination). 

Simple observation is not always a suitable means of identifying patterns. 

For instance, blackening can occur due to smoke deposition or thermal 

decomposition of the underlying material. Loss of coatings like paper or 

plastic films can further complicate the identification of patterns of 

damage. Apparent clean burn patterns can also result from shedding of a 

surface coating. 

It is common for fire investigators to identify a fire pattern where they have 

not identified the underlying fire effects that caused the various parts of the 
65

overall pattern. This compromises the utility of pattern identification. Close 

examination/photography or even microscopy of a local surface will help 

identify the fire effects as will superficial delayering of the surface.

Electrical activity patterns (arc mapping) require close scrutiny of the 

entirety of the electrical system and devices within the fire area. Wide 

photographs can provide overall documentation of where the electrical 

activity is but close up photography is needed to document the details of 

the electrical activity. 

Similarly, identification of potential ignition sources is not achievable with 

only wide view photographs. Identification of electrical activity and 

potential ignition sources requires a highly detailed examination of the fire 

scene, sifting the relevant artifacts from the bulk of the debris. Sieves and 

magnets are often required.

Fire scene reconstruction is an important investigative tool. The large 

quantities of fire debris in the fire scene obscure the original configuration 

of objects, and reconstruction allows the pre-fire configuration to be 

established and puts the fire effects on different objects in context for 

comparison. The reconstruction process identifies patterns in damage that 

cannot be observed in the fire scene as found. The process of debris 

removal and reconstruction is an involved and time-consuming task, but 

one that provides pattern data for analysis.

Fire pattern analysis is the application of fire dynamics to understand the 

fire development consistent with the fire effects and patterns. The analysis 

is not a static analysis but rather seeks to identify the sequence of the 

formation of fire effects and patterns. The detailed nature of the fire load 

throughout the scene and the ventilation openings has significant impacts 

on the fire effects and patterns that need to be incorporated into the fire 

dynamics analysis.

Scene examination for the determination of the fire cause includes 

identification of potential ignition sources and the fuels which are available 

to be impacted by these potential ignition sources. Failures that cause fires 

may be localized to an area the size of a grain of rice or smaller. 
66

Identification of evidence of such failures involves detailed examinations 

that may require many hours of scene work. Often the results of a scene 

examination include the collection of items for further laboratory analysis 

to understand the role of the potential ignition source in the fire scenario. 

Since all potential ignition sources within the area of origin need to be 

considered in the formation of cause hypotheses, this painstaking work is 

an essential part of the fire scene examination.

In explosion events, the damage to and displacement of items are critical to 

understanding the severity of the explosion and its origin. An 

understanding of the damage to and trajectory of items by the impulse 

loading of the explosion is key to understanding the explosion event. 

Frequently, understanding explosion damage is complicated by the effects 

of the subsequent fire.

5-2 Documenting the Scene

Fire investigators are required to receive minimum training in the 

methodology of fire scene documentation and must have specific abilities 

to document scenes. However, the specific amount or type of training 

required is not quantified by any single standard. Minimally, at least one 

fire investigator is obligated to sufficiently document a given fire scene. 

There is substantial guidance within authoritative texts in the field as to 

how to document the fire scene investigation. For example, the evidence is 

documented in place, fire scenes are photographed, and measurements are 

taken to assist with scene reconstruction. However, the amount and quality 

of fire scene documentation depend on the investigator’s or expert’s role 

(or that of their employer). This role also drives what type of report, if any,

will be produced to memorialize the investigation. While there is no 

universal mandate to write a report, one may be required before an 

investigator is allowed to testify to the results of an investigation. In the 

federal courts and many other jurisdictions, testimony will be subject to 

exclusion if the fire investigator has not prepared a report. For more 

information on reporting requirements, see Chapter 3-3.
67

The act of documenting the scene and recording data during the 

investigation is the first step, while the second step is the production of a 

report. The report typically provides a synopsis and analysis of the 

investigation and relies, in part, on the data documented while on the fire 

scene. However, while the scene will always be documented to some 

degree, the production of a report is not a given. There are some agencies 

whose documentation is so poor that it does not even include a diagram, 

and the photographic documentation is insufficient for a subsequent 

investigator to understand the fire scene or its investigation. 

The degree of scene documentation is driven by the need to preserve data 

for later analysis, not necessarily for reporting requirements. The 

investigators are charged with casting a wide net — they may not know at 

the time of the scene investigation what will be important data and 

therefore should document, within reason, all data related to the fire scene 

and specific incident. Like other fire investigation data, investigators 

should consider the data gained from the scene within the context of other 

data (such as interviews) developed during the investigation. The 

perceived importance of scene data in fire investigation may change. It is 

not unusual for data collected from the scene to be unimportant early in the 

investigation and then to become important later (or vice versa). 

Fire investigators typically document data which may be subsequently 

reviewed, analyzed, and summarized into an origin and cause report. This 

report will be used to communicate findings and the bases for those 

findings. 

Fire investigators typically examine a fire scene from the exterior to the 

interior, documenting items of interest (data) as they proceed. The 

documentation should illustrate a systematic approach to the fire 

investigation. Documentation of the scene may require the use of special 

tools or accessing areas outside of the scene. In larger fire scenes, involving 

a team of investigators, documentation responsibilities may be divided. 

One investigator may be designated to be the photographer, another 

investigator tasked to take notes, and yet a third investigator is designated 

to map the scene forensically. Safety considerations may affect the ability to 

document a scene thoroughly. Weather and lighting conditions also play a 
68

role and may dictate when and where an investigator can document the 

scene. 

Photography is perhaps the most important technique used to document 

the scene. NFPA 921 [2021] Section 16.2.1 recognizes that photographs are:

“... the most efficient and effective reminders of what the investigator saw 

while at the scene. Important items that were documented by photography 

may become more evident upon review of the photographs or videos. 

Photographs and video are necessary to substantiate the investigator’s 

observations”.

Photography should be done in conjunction with a photograph log to 

describe each photograph and its perspective accurately. There is guidance 

in NFPA 921 on how to create a photo log.

Note-taking is another standard method of documentation and is widely 

used. There is no standard as to the extent of notes, content, or format. As 

NFPA 921 Section 16.3.1 states,

“The use of forms is not required in data collection; however, some forms 

have been developed to assist the investigator in the collection of data. These 

example forms and the information documented are not designed to 

constitute the report but instead provide a means to gather data that may be 

helpful in reaching conclusions so that a report can be prepared. (See 

A.16.3.2.)”.

Notes should be retained. The failure to retain notes hinders the ability of 

other experts to analyze the same set of data documented and analyzed by 

the initial fire investigator. Additionally, the destruction of notes (which 

are evidence) can leave the impression that the investigator is hiding 

something. 

Diagrams and sketches are used to assist investigators in understanding 

fire growth and development. These may be later used to communicate 

findings, to explain photographs and evidence, or to assist in witness or 

suspect interviews. NFPA 1033 identifies that a requisite skill to be a fire 
69

investigator is to be capable of producing a sketch and diagram of a fire 

scene. NFPA 921 provides guidance on what to include in the legend and 

how best to label a diagram.

Documenting Patterns

Fire patterns are some of the most important data to document. The 

foundation of fire scene investigations consists of identifying, recognizing, 

documenting, and interpreting fire patterns. These patterns may yield data 

that helps to establish area(s) of origin and to identify potential ignition 

sources. Per NFPA 921, the investigator will use three factors, including fire 

pattern analysis, to identify an area of origin before identifying a cause. The 

analysis of patterns will be aided by “reconstruction” of the scene by 

investigators. This reconstruction varies in magnitude and generally 

consists of clearing debris and placing significant fuel packages back in 

their pre-fire positions to visualize fire patterns and undamaged areas 

better. Patterns are documented through photography but may also be 

documented through notes, measurements, and sketches or diagrams. In 

rare circumstances, a pattern may be collected as evidence by taking the 

underlying substrate into evidence.

Documenting Physical Evidence

Fire investigators will also document physical evidence as it is identified, 

collected, and examined. Not only is there a legal requirement to do so (i.e., 

chain of custody documentation and evidence logs), but there is an 

obligation to do so since the evidence may not be preserved beyond the 

scene examination. There is a wide variety of items in a fire scene that 

could be considered evidence, such as debris, patterns, appliances, 

containers, blood spatter, and NFPA 921 provides guidance on when to 

properly document much of these specific items of evidence. During the 

fire scene investigation, investigators are expected to identify the evidence 

and document it in place as well as in context with the rest of the scene. 

The processing of the evidence, whether that be collection or removal of 

other debris around it, is further documented. The chain of custody is 

documented as well before leaving the scene. Done correctly, this will 
70

allow for third-party analysis of the evidence and protection against 

charges of spoliation.

Documenting Structures and Building Systems

Investigators will often need to evaluate a structure’s construction as well 

as the systems contained within them. The design and construction of a 

structure will often dictate fire growth. Components within the structure, 

such as the electrical or HVAC systems, have to be considered when 

assessing ignition sources as well as their influence on fire growth. It is 

critical for investigators to have a thorough understanding of these 

elements if they are to render accurate opinions about the origin and cause 

of a fire. Investigators will typically use photography, note-taking, and 

diagramming to document the type of construction, the materials used in 

construction, and the compartmentation within it. Also, investigators 

document various pieces of the electrical service, natural gas or propane 

service, HVAC components, alarm systems, and fire suppression systems. 

This effort often will include arc mapping, which involves the 

identification and documentation of a specific type of pattern found on 

electrical conductors.

Documenting Personnel and Processes

Investigators may document personnel processing the fire scene as well as 

scene investigation processes. This is usually done through photographs 

and notes. For example, investigators may document the use of an 

Ignitable Liquid Detection Canine team, the use of heavy equipment, and 

when witnesses are walked through the scene. 

The purpose of documenting these activities is to allow investigators to 

create a narrative as to how they employed a systematic approach to their 

fire investigation. This preserves their ability to explain how their scene 

investigation developed and proceeded. 
71

Documenting Testing

Fire investigators may conduct field tests in furtherance of testing their 

origin and cause hypotheses. As with other processes, these tests are 

usually documented with photography, video, and notes. This 

documentation will serve to strengthen hypothesis development and 

testing, as well as any conclusions based on the test data. 

Best Practices Recommended by NFPA 921

NFPA 921 provides guidance on how and when to document a fire 

investigation. Consideration is given to the fact that some investigators 

may not have had an opportunity to access the scene. NFPA 921 puts the 

responsibility of properly documenting a scene on at least one party so that 

other parties can use the same data to conduct their investigation 

successfully. As Section 4.4.3.3 states,

“In any incident scene investigation, it is necessary for at least one 

individual/organization to conduct an examination of the incident scene for 

the purpose of data collection and documentation. While it is preferable that 

all subsequent investigators have the opportunity to conduct an independent 

examination of the incident scene, in practice, not every scene is available at 

the time of the assignment. The use of previously collected data from a 

properly documented scene can be used successfully in an analysis of the 

incident to reach valid conclusions through the appropriate use of the 

scientific method”.

Section 4.4.3.4 further states,

“Improper scene documentation can impair the opportunity of other 

interested parties to obtain the same evidentiary value from the data. This 

potential impairment underscores the importance of performing 

comprehensive scene documentation and data collection”. 

NFPA 921 devotes an entire chapter to scene documentation, describing 

how the goal of this documentation is to make an accurate recording of the 

investigation that will, in turn, allow investigators to recall and 
72

communicate their findings, detail their analysis and basis for opinions, 

and preserve data for others to use. The chapter details the recommended 

techniques for a variety of commonly used documentation techniques such 

as photography, note-taking, and diagramming. The chapter does not 

quantify the amount of documentation needed, nor its format.

NFPA 921 also provides explicit guidance in another ten chapters for 

documenting specific areas of the fire scene investigation. These chapters 

address things such as Building Systems, Active Fire Protection Systems, 

Electricity and Fire, Physical Evidence, Appliances, Motor Vehicle Fires, 

Explosions, Marine Fires, and Wildfire Investigations.

A fire scene investigation is a complex endeavor, requiring the collection 

and compilation of data, and subsequent analysis of that data. Fire 

investigators have to skillfully use their knowledge of science and 

technology to collect and evaluate this data properly. Accurate 

documentation of this data lends itself to rigorous hypothesis testing and 

accurate conclusions, whereas the poorly documented scene can lead to 

erroneous analysis. In short, scene documentation is the foundation for 

proper fire pattern analysis, hypothesis development and testing, failure 

analysis, and testimony.

Complete and thorough documentation of scene data is important because 

the relevance and importance of that data may only be understood at a 

later time. Data used to form a conclusion about the origin and cause of a 

particular fire are drawn from many different sources. These include 

sources outside (e.g., a witness interview) and inside the actual fire scene 

(e.g., fire patterns). This documentation will not only be used by the fire 

investigator to communicate their analyses and conclusions but will be 

used by others to develop their analyses and conclusions.

Assessment of Current Practice

The documentation of fire scene data is inconsistent throughout the 

country, governed by few standards, and may be mostly dictated by the 

role of the investigator or expert. Consensus standards exist, for example, 

ASTM E1188, which provides minimum documentation requirements for 
73

forensic science disciplines. It is a sad fact that many fire investigators are 

unaware of ASTM E1188 or see no need to comply with this generally 

accepted standard. 

Documentation of the scene can be considered a two-part process. The act 

of documenting the scene and recording data during the investigation is 

the first step, while the second step is the production of a report. Reports 

are covered extensively in Chapter 3. The report typically provides a 

synopsis and analysis of the investigation. Though inextricably related, 

these two steps can be considered separately.

There are some broad mandates to report content, but these are so 

unspecific that there is no consistency among agencies (public or private) 

that produce reports. Beyond the obvious instruction to detail data 

supporting conclusions in origin and cause reports, there is a deliberate 

silence by authoritative texts in the field as to what should specifically be 

contained in an origin and cause report. NFPA 921 Guide for Fire and 

Explosion Investigations [NFPA 2021], Section 16.5, states,

“The final step in the documentation of the investigation may be the 

preparation and submittal of a report. The format and content of the report 

will depend on the needs of the organization or client on whose behalf the 

investigation was performed. Therefore, no report format is prescribed here.” 

To complicate matters, often the nature of fire litigation produces opposing 

parties. These investigators or experts may enter a particular fire 

investigation (or associated legal action) at different points in time. 

Therefore, the actual fire scene may not be available to all parties for 

examination. One or more parties may rely on the original investigating 

agency’s documentation to conduct their origin and cause investigation to 

formulate their own opinions.

Recent advances in technology (e.g., digital cameras, laser scanning, 

unmanned aerial vehicles) have made it easier to document fire scene 

investigations. Unfortunately, this does not necessarily translate to betterdocumented fire scene investigations. The lack of mandated scene 

documentation training and protocols may account for this slow progress.
74

5-3 Evidence Collection/Preservation

According to NFPA 921, physical evidence can generally be defined as 

“any physical or tangible item that tends to prove or disprove a particular 

fact.” 

Without proper evidence documentation, collection, and preservation 

procedures in place, the value of any physical evidence that has been 

collected can be highly diminished. 

Typically, documentation, collection, and preservation of evidence from a 

fire or an explosion scene are the responsibility of the fire investigator. 

Therefore, fire investigators need to have an appreciation of the value of 

identifying, documenting, protecting, collecting, and preserving physical 

evidence before beginning an investigation. There is a wide range of 

sources of information to gain this fundamental knowledge [NFPA 921, 

ASTM E1188, ASTM E1459]. However, knowledge of the evidence 

collection process is not sufficient. Investigators typically train under 

another investigator to gain practical experience in correct evidence 

handling procedures. 

Investigators need to also have an understanding of their particular 

laboratory’s capabilities in regards to an examination of physical evidence. 

The best way to gain this understanding is to visit and talk with laboratory 

examiners before submitting evidence. 

Evidence Identification

Fire scene evidence, in general, is not like evidence from other crime 

scenes. The fire and explosion scene is a harsh environment. Heat, flame, 

smoke, and high pressures in a fire and explosion scene are likely to 

damage or alter physical evidence. Given this possibility, the investigator 

seeking to collect physical evidence needs first to identify what physical 

evidence may be present at a fire or explosion scene. 
75

Ignitable liquid detection canines (IGL canines) have been used as a tool for 

assisting the fire investigator in locating and identifying physical evidence 

for ignitable liquid residue analysis by a laboratory. When used properly, a 

proficient IGL canine team can be a valuable tool for fire investigators. If 

used in the search for evidence, it is important for the fire investigator to 

understand the capabilities and limitations of IGL canines [CADA 2012]. 

It is important to understand the type of evidence that is being collected. 

For example, when collecting fire debris for ignitable liquid examinations, 

the investigator should be familiar with the properties of the ignitable 

liquids. Some soils contain microbes that could potentially degrade 

ignitable liquids. This can be mitigated by freezing or refrigerating the soil 

sample. Similar problems arise due to mold formation on fire scene 

surfaces.

One important aspect of fire and explosion evidence is the need to collect 

comparison samples. Given the prevalence of ignitable liquids and 

consumer products that are manufactured from petroleum distillates, 

investigators need to collect comparison samples of materials from an area 

that can reasonably be expected to be protected from the fire. For example, 

when collecting carpet or other flooring samples that are suspected of 

containing ignitable liquids, the investigator should collect the same 

flooring samples from the scene that are not expected to contain ignitable 

liquid residue to serve as a comparison sample. This allows the laboratory 

examiners to evaluate the chemical contributions from the background. 

To prevent cross-contamination of evidence samples, proper protocols for 

the decontamination of boots and tools should be followed. The 

investigator should have a general awareness of the consequences of crosscontamination.

Protection of Evidence

The protection of potential fire and explosion evidence is the responsibility 

of everyone at the scene. The fire investigator is not the only one that bears 

this responsibility; first responders that are involved in fire suppression 

and overhaul efforts should also be aware of correct procedures to protect 
76

evidence. Personnel at a fire scene should at all times be aware of the need 

to protect the evidence and to preserve the integrity of each item by 

protecting it from loss, contamination, and degradation. Once potential 

evidence is identified, the investigator or responsible party should take 

steps to protect the evidence. ASTM Standards E860 and E1188 should be 

consulted for more specific procedures for protecting potential evidence. 

Storage and Disposal of Evidence

Once the evidence has been properly collected and packaged, the 

investigator should submit the evidence for examination as soon as 

practical. In the time between collection and submission, it is important to 

properly store evidence. Procedures for storage of the evidence should 

account for the type of evidence, specific preservation requirements, 

managing access to the evidence, and the temperature of storage facilities. 

When transporting evidence, care should be taken to prevent damage, 

contamination, or spoliation of the evidence. 

Disposal of evidence should follow specific requirements of the 

investigating agency. Consideration should be given to the statute of 

limitations, other parties who may have an interest in the evidence or 

returning the evidence to the original owner. 

5-4 Interviews

Interviews are critical in nearly all fire investigations, often providing data 

necessary and relevant for origin and cause hypothesis development and 

testing. During fire investigations, interviews are typically conducted of a 

combination of first responders, the fire discoverers, occupants, witnesses, 

property owners, and so on. In cases where the fire cause is determined to 

be incendiary, there may be a custodial or non-custodial suspect interview.

Moreover, the interviews may take place over multiple intervals during or 

after the actual scene investigation.

Interviews identify data helpful to determining fire origin and spread, the 

configuration of fuels, contents, and compartments, presence and state of 
77

ignition sources, state of repair or disrepair of property or equipment, fire 

timeline, intentional or unintentional acts related to the fire, suppression 

efforts and tactics, and other useful information. Interviews provide 

context to other data identified during the fire investigation. 

Types of Interviews (custodial and non-custodial)

Fire investigators frequently conduct non-custodial interviews of witnesses 

to gather data pertinent to the fire investigation. This type of interview is 

typically limited to issues surrounding origin and cause of the fire. These 

interviews often occur contemporaneously with the fire investigation, and 

witnesses may even be on hand at the scene to point things out to 

investigators. The type of witness will dictate the type of information being 

solicited, and investigators must be proficient in communicating on 

technical matters as well as simple issues. An interview with a first 

responding firefighter will utilize different terminology than that with a 

passer-by. The interview may consist of several different phases and may 

occur multiple times as investigators narrow their origin and cause focus.

Custodial interviews, typically of those suspected of setting the fire, can be 

the most challenging. A custodial interview is not necessarily predicated on 

an incendiary cause determination. The tactics and preparation for this 

type of interview are unique. Depending on the jurisdiction, the custodial 

interview may be undertaken by the fire origin and cause investigator or 

by law enforcement personnel unrelated to the fire investigation. The 

recent debate over the bifurcation of roles and responsibilities of fire 

investigators has challenged the notion that the lead fire investigator 

should be involved in every interview in a given fire investigation. In 

custodial interviews of a suspect, at least one of the interviewers should be 

a fire investigator (not necessarily the lead fire investigator) who is wellversed in fire science as well as that particular fire investigation. This is so 

that the proper analysis of the suspect’s statements can be made, and 

scientifically challenged if necessary.

In many instances, a canvas of a particular neighborhood will be 

undertaken. This effort is an attempt to speak with witnesses who have not 

yet come forward or previously been contacted by investigators. Effective 
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canvasses by trained fire investigators gather more germane information 

about the fire’s origin and spread, as well as its timeline.

Interview Preparation 

Fire investigators typically prepare for interviews by reviewing data from 

the fire scene, analyzing other witness statements, and speaking with other 

investigators. This preparation is vital for a thorough interview and may 

include a checklist or use of a questionnaire. In particular, for fire 

investigators not involved in processing the fire scene, it is imperative that 

they understand the various hypotheses concerning the origin and cause of 

the fire. Investigators also use diagrams, pictures, documents, or artifacts to 

help with interviews. 

Difficulties Encountered in Interviews

Fire investigators encounter numerous challenges during interviews. These 

may include language or cultural barriers, the inability of the investigator 

to communicate in a non-technical manner, difficulty in conversation with 

victims, poor environmental conditions when conducting the interview, 

hostility from the witness, and limited accessibility of the witness. These 

variables require investigators to be flexible, adaptable, and to have an 

interview strategy consistent with the witness and the situation. Witnesses 

may need to be interviewed more than once. In NFPA 1033, it is recognized 

that investigators must have the skill and ability to, “adjust interviewing 

strategies based on deductive reasoning...” [NFPA 1033, p. 9] 

Some difficulties are self-imposed by investigators. Investigators may miss 

vital data if they do not properly analyze or follow up on witness 

statements. 

Documentation of Interviews

Interviews, like any other relevant piece of data, must be documented. This 

typically is done through notes but may also include an audio or video 

recording. Recordings and notes taken during the interview should be 

retained. Following the interview, it is typical for a written synopsis to be 
79

produced. Also, some investigators will produce a written statement or 

have the witness write a written statement synopsizing the interview. This 

written statement is reviewed and corrected by the witness who ultimately 

signs it.

Analysis of Interviews and Context

Investigators must consider the data gained from the interview within the 

context of other data developed during the investigation. Many times, the 

data from the fire scene is consistent with the witness statements. This does 

not absolve investigators from critically analyzing it. At times there are 

data from the fire scene or other witnesses which may contradict a witness 

statement. This does not necessarily mean the witness was untruthful; 

rather, their perception may have been inaccurate or incomplete. 

Investigators should attempt to resolve conflicts among the witness 

statements and the scene or case data. 

It is not unusual for data collected from interviews to be irrelevant early in 

the investigation and then to become relevant later (and vice versa). 

Because of this, the lead fire investigator is tasked with analyzing all of 

these interviews. This analysis may dictate re-interviewing some witnesses. 

Before coming to a conclusion, the lead fire investigator’s goal is to use the 

interview data to test origin and cause hypotheses developed during the 

investigation.

5-5 Post-Incident Investigation (Non-scene)

Non-scene data” is that which is relevant to some aspect of the fire origin 

and cause investigation but is not contained within the actual fire scene. 

Investigators collect “non-scene data” and may use it to help establish the 

fire or explosion timeline, identify an area of origin, document the growth 

and spread of the fire, identify suppression efforts which may have 

affected fire growth and spread, provide context to another piece of data, 

or to establish evidence of causation (e.g., lightning, intentional human 

acts). In rare instances, non-scene data may be the most relevant data used 

to determine an area of origin or a fire cause. 
80

Therefore, fire investigators often analyze and document areas outside of 

the actual fire scene. They may be attempting to identify evidence, explore 

vantage points of witnesses or security cameras, examine circumstances 

leading up to the fire, or to obtain data which helps the investigator 

understand the overall context of the incident.

“Non-scene data,” as described in this document, is distinctively different 

from evidence used to establish responsibility, motives, means, and 

opportunity. The “non-scene data” referred to in this document is only 

relevant to identifying where the fire started (origin) and the circumstances 

that brought an ignition source into contact with the first fuel ignited 

(cause). 

Some examples of “non-scene data” include:

● Witness statements (including suspect statements)

● Alarm system activity 

● Suppression system activity 

● Videos or pictures taken by cameras in or outside the fire scene

● Cellular telephone activity recorded on routers, cell towers 

found outside of the scene

● Weather reports

● Safety Data Sheets (SDS)

● Burn injuries and toxicological analysis of fire victims

● Recall notifications 

● Code enforcement documentation

● Banking, real estate, or insurance files documenting pre-fire 

physical conditions at the location

● Architectural diagrams or similar documents providing pre-fire 

building construction data

● Fire modeling

● Field or laboratory testing results

● Physical evidence collected outside of the scene

● Smart meter readings
81

NFPA 921 and 1033 and “Non-Scene Data”

NFPA 921 [2021] recognizes that data may come from a wide range of 

sources, stating in Section 14.1 

“The scientific method requires the collection and analysis of data. This 

chapter is intended to provide a framework for collecting and analyzing data 

from sources other than the scene of the incident (non-scene data) using the 

scientific method. Examining the fire scene or evaluating prior 

documentation of the fire scene, interviewing witnesses, and conducting 

research and analysis of information from other sources all provide the fire 

investigator with additional data to establish origin and cause of a particular 

fire. Subsequent to the origin and cause determination, non-scene data may 

be helpful to evaluate responsibility for a fire.”

Also, NFPA 921 section 4.4.3.2 does not specify sources of data but leaves 

this concept open-ended:

“The actual investigation may include different steps and procedures, which 

will be determined by the purpose of the assignment... A fire or explosion 

investigation may include all or some of the following tasks: a scene 

inspection or review of previous scene documentation done by others; scene 

documentation through photography and diagramming; evidence 

recognition, documentation, and preservation; witness interviews; review 

and analysis of the investigations of others; and identification and collection 

of data from other appropriate sources”.

NFPA 921 has recognized the value of “non-scene data.” The document 

identifies three factors to be used when determining the origin. One of 

those factors speaks to the coordination of information derived from “nonscene data.” Changed in the most recent edition to reflect the consideration 

of electronic data, Section 18.1.2 states,

“Determination of the origin of the fire involves the coordination of 

information derived from one or more of the following:

(1) Witness Information and/or Electronic Data. The analysis of 

observations reported by persons who witnessed the fire or were aware of 
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conditions present at the time of the fire as well as the analysis of electronic 

data including but not limited to security camera footage, alarm system 

activation, or other such data recorded in and around the time of the fire 

event...”.

Also, NFPA 921 Section 18.3.3 lists specific data to consider when 

determining the origin, much of which would be considered “non-scene 

data” such as pre-fire conditions, weather history, alarm systems, and 

witness statements.

NFPA 1033 [2022], does not specifically address “non-scene data,” focusing 

largely on “scene data.” Also, a discussion of post-incident investigation 

job performance requirements includes collecting a variety of data, but the 

document is addressing issues of responsibility rather than origin and 

cause with this language. 

The Value of “Non-Scene Data”

Depending on the type of fire scene, some or none of this data will be 

available to investigators. Even if it is available, its value may be negligible, 

or its value may not be realized until later in the investigation when other 

additional data is uncovered and analyzed. For example, a security camera 

across the street from the fire scene may have recorded relevant footage of 

the fire spread or may have no footage if it was facing the wrong direction. 

Even if it faced the wrong direction, perhaps it captured data relevant to 

the circumstances leading to the fire (e.g., lightning strike, vehicle striking a 

gas meter).

For most fire scenes, there exists “non-scene data” which usually provides 

critical context to the “scene data.” The failure to collect and to consider 

certain types of “non-scene data” could lead to erroneous conclusions. 

Analysis of “Non-Scene Data”

As with data from the fire scene, the analysis of “non-scene data” must be 

placed within the context of the larger fire investigation. Most of this type 

of data cannot stand alone — in and of itself, it may mean very little. The 
83

data must be used in concert with other data derived from the scene to

have a correct interpretation. Also, if a piece of “non-scene data” is 

inconsistent with other data generated in the case, the investigator is 

obligated to resolve this inconsistency. “Non-scene data” carries a distinct 

burden — the investigator must articulate why it is relevant to the origin 

and cause of the fire, and provide contextual analysis. 

Due to the wide variety and sometimes nontraditional nature of “nonscene data,” fire investigators may not be trained to identify, collect, or 

analyze that particular data (e.g., cellular tower data). Fire investigators 

must be aware of their limitations and be aware enough to call upon other 

resources when needed. 

The most common laboratory analysis conducted in fire investigations is 

ignitable liquid residue testing using gas chromatography/mass 

spectrometry. Testing methods used by other forensic science disciplines 

are also employed. Additional laboratory analyses that may be conducted 

are listed in Table 5-1. 

Table 5-1: Laboratory Analyses 

LABORATORY TECHNIQUE PURPOSE OF ANALYSIS

FTIR- Fourier Transform 

Infrared spectroscopy.

Identify chemical composition

Optical Microscopy Magnified visual examination 

Polarized Light Microscopy Chemical / mineral composition 

Radiography Visualizations of the internal 

structure

CT Scan Visualizations of the internal 

structure

SEM/EDX-Scanning Electron 

Microscopy / Energy Dispersive 

X-ray analysis

Magnified visual examination and 

elemental composition

Infrared Thermography Thermal imaging 
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Evidence Examination Protocols

The purpose of the protocol is to describe the tasks that are anticipated. The 

protocol should be circulated among the parties, and comments sought. 

This type of pre-planning often brings out issues that can be resolved 

before an examination. Parties can be assured that the necessary test 

equipment will be made available.

A laboratory examination is an investigatory process conducted to find 

answers. Often, the exam will reveal new data that will logically dictate a 

change in the protocol. 

5-6 Presentations

The culmination of these scene documentation efforts is usually a written 

report. The content of a written report depends on the agency or party 

requesting the investigation, the type of expert used, and the scope of their 

particular analysis. These same factors affect what type of report will be 

produced, or if any report will be produced at all (reports are almost 

always required when litigation is joined). Virtually all public sector 

agencies produce a written origin and cause report designed to detail the 

fire investigation. There is no standardized format, but at a minimum, the 

report should list the investigator’s opinions and the bases for them. 

An origin and cause report generally addresses several factors related to 

the fire incident: date, location, the identity of victims and occupants, fire 

department response. The report details the data collected at the scene such 

as observable fire patterns, physical evidence collected, the state of utilities 

and appliances, interviews, non-scene data, and what was done to process 

the scene. This data is then used to test hypotheses developed during the 

investigation. Ideally, the report will describe the circumstances that 

brought an ignition source and a first fuel together. Lastly, the report may 

list the fire cause classification as natural, accidental, incendiary, or 

undetermined in accordance with NFPA 921.
85

There is a lack of consistency in retention policies. These policies and laws 

vary from state to state, allowing investigators in some regions to discard 

their notes following the production of a formal report. The destruction of 

such documentation not only violates best practices described in NFPA 921 

but may also constitute spoliation of evidence in that other experts are 

unable to review the data. 

ASTM E620-2018, Standard Practice for Reporting Opinions of Scientific or 

Technical Experts, addresses the scope of information to be contained in 

formal written technical reports (which would include origin and cause 

reports). The standard addresses report content, including descriptive 

information, pertinent facts, and opinions and conclusions.

E1020-2013, Standard Practice for Reporting Incidents that May Involve 

Criminal or Civil Litigation, addresses the collection and preservation of 

information and physical evidence. It also addresses the preparation of a 

documentation report relative to fire scene investigations. The standard 

requires the report to contain a detailed chronological narrative, 

photographs accurately depicting the scene, identification of items or 

systems involved in the incident, identification of persons involved in the 

incident, details concerning evidence and any subsequent chain of custody.

5-7 Conclusions

Fire and explosion investigation involves the determination of the origin, 

the cause, and the development of a fire or explosion. The investigation 

process is fundamentally based on the scientific method. Once the area of 

origin is determined, all potential ignition sources are identified within that 

area. Cause hypotheses are developed which include the ignition source, 

the first material ignited, and the events that brought the fuel and ignition 

source together (ignition sequence). The cause hypotheses are tested 

against the investigation data and the principles of fire science. A cause is 

determined if one and only one cause hypothesis survives hypothesis 

testing.

The data collection processes are carried out at the scene, as well as 

information sources outside the scene. Processes involve evidence 
86

identification, collection, protection, documentation, and preservation. 

Data includes witness information, electronic data, fire damage patterns, 

physical evidence, arc mapping, fire dynamics analysis, and 

documentation of the building, its systems, and its contents at the time of 

the fire. Fire scene processing includes direct observation, 

photography/videography, debris delayering and examination, sample 

collection, as well as measurements of the building and the fire damage. 

Analysis of the data often requires the use of subject matter experts for 

specific types of analyses (e.g., chemists, engineers).

The data from the investigation is presented and analyzed via the scientific 

method in the investigation report to produce conclusions about the fire. 

Fire and explosion investigators are also called upon to provide testimony 

in depositions, hearings and trial appearances as an expert witness.

REFERENCES

ASTM (2018), Standard Practice for Reporting Opinions of Scientific or Technical 

Experts, ASTM E620-2018

https://www.astm.org/Standards/E620.htm

ASTM (2013), Standard Practice for Reporting Incidents that May Involve 

Criminal or Civil Litigation, ASTM E1020-2013

https://www.astm.org/Standards/E1020.htm

ASTM (2014), Standard Practice for Collection and Preservation of Information 

and Physical Items by a Technical Investigator, ASTM E1188-2014

https://www.astm.org/Standards/E1188.htm

ASTM (2018), Standard Guide for Physical Evidence Labeling and Related 

Documentation, ASTM E1459-2018

https://www.astm.org/Standards/E1459.htm

Carman, S. (2008). Improving the Understanding of Post-Flashover Fire 

Behavior. Proceedings of the 3rd International Symposium on Fire Investigations 

Science and Technology (ISFI), NAFI, Sarasota, FL. 
87

http://www.carmanfireinvestigations.com/

Tinsley A.T. and Gorbett G.E. (2012), Fire Investigation Origin 

Determination Survey. International Symposium on Fire Investigation Science 

and Technology (ISFI), pp. 53-68. 

https://ssem.eku.edu/sites/ssem.eku.edu/files/files/Gorbett%20-

%20FIRE%20INVESTIGATION%20ORIGIN%20DETERMINATION.pdf

Cox, A. (2013). Origin Matrix Analysis: A Systematic Methodology for the 

Assessment and Interpretation of Compartment Fire Damage. Fire and 

Arson Investigator, International Association of Arson Investigators, Vol. 64, 

pp. 37-47

Gorbett G, Meacham B, Wood C, Dembsey N (2015). Use of Damage in Fire 

Investigation: a review of fire patterns analysis, research and future 

direction. Fire Science Reviews, 4:4, 

https://doi.org/10.1186/s40038-015-0008-4

NFPA (2022), Standard for Professional Qualifications for Fire Investigator, 

NFPA 1033, Quincy MA.

http://www.nfpa.org/codes-and-standards/all-codes-and-standards/listof-codes-and-standards?mode=code&code=1033

NFPA (2021): Guide for Fire and Explosion Investigations, NFPA 921, 

Quincy, MA. 

http://www.nfpa.org/codes-and-standards/all-codes-and-standards/listof-codes-and-standards?mode=code&code=921
88

6. IMPROVING METHODS, PRACTICE, AND

PERFORMANCE IN FIRE AND EXPLOSION

INVESTIGATION

6-1 Introduction

The first five chapters of this strategic plan summarize how fire and 

explosion investigation is organized and carried out under the current 

system. There is a need to move forward to strengthen the practice of fire 

investigations through new practices and procedures, based upon a firm 

foundation of fire science and implemented through a strengthened 

operational system that includes strong management systems for fire 

investigation units (both public and private). This chapter deals with the 

need for enhancement of the methods, practice, and performance in fire 

and explosion investigation. Issues related to the needed research (Chapter 

7), operation of fire investigation units (Chapter 8) and related education 

and training of fire and explosion investigators (Chapter 9) are addressed 

in subsequent chapters.

6-2 Team Approach to Fire and Explosion Investigation

The investigation of most fires begins with the first responders to the fire 

event. Each firefighter has responsibilities to identify and preserve 

evidence that potentially relates to the determination of the origin and 

cause of the fire. Indiscriminate overhaul19 operations have compromised 

many investigations. A caricature of the indiscriminate overhaul is the 

arrival of the fire investigator on the scene to find the contents of a room in 

a pile outside a window, placed there by first responders. This brings home 

the fact that a quality investigation requires the expertise and collaboration 

of all participants. While the archetype of a fire investigator has been a lone 

19 3.3.135 Overhaul. A firefighting term involving the process of final extinguishment 

after the main body of the fire has been knocked down. All traces of fire must be 

extinguished at this time.
89

wolf who examines a fire scene, a team approach to a fire investigation is 

more effective and necessary [IAAI 2017].

The need for a team approach has three complementary aspects; 1) safety, 

2) the diversity of technical skills required, and 3) the role of collegial 

interaction in identifying all the available evidence, all the hypotheses that 

arise from that evidence, and all the hypothesis testing required to reach a 

proper conclusion. Team interactions may reduce unwarranted 

assumptions and biases.

Early in the investigation, police and fire department responding units can 

assist in securing the scene and in scene safety assessment. While police 

and fire department personnel may have some training in rudimentary fire 

investigation methods, they consist essentially of not fully trained fire 

investigators and should only perform fire investigation tasks at the 

direction of a fully trained fire investigator.

Working safely on the fire scene requires multiple people. Working a scene 

alone needs to be avoided [NFPA 921 2021 §13.2.1]. The need for additional 

investigators grows with the size and complexity of the fire scene. See 

NFPA 921 [2021] Chapter 13 for additional guidance on fire scene 

investigation safety.

The need for a team approach in complex scenes has long been understood. 

ATF has had National Response Teams (NRT) in the field since 1978 [ATF 

2016]. The NRT’s have been activated more than 800 times in the 40-year 

history of the response teams (about 20 per year) [ATF 2016a]. Each NRT 

includes Certified Fire Investigators (CFI’s), Bomb Technicians, Scientists/ 

Engineers, Detection K-9’s and Handlers, Forensic Auditors, and additional 

experts as required. 

Some State Fire Marshal Offices (SFMOs) also employ a team approach, 

providing local investigation organizations with investigators with 

specialized training and experience. In particular, specific technical experts 

are generally not readily available at the local level and may be more 

effectively provided by a state agency.
90

Even at the local level, groups of jurisdictions band together to form 

response teams made up of investigators from each participating 

jurisdiction. This provides a means of forming a team with a scope and 

diversity of skills that no single jurisdiction could muster alone. Working 

together provides additional opportunities to transfer skills and practices 

to work toward universal best practice operations in all the jurisdictions. 

Arson task forces exist as well, their purpose being to conduct long term 

follow up investigations of intentionally set fires. An ancillary benefit of 

task forces is that the members get the experience of investigating more 

fires than they would if they only investigated fires in their home 

jurisdiction. 

Finally, and perhaps most importantly, working as a team in all 

investigations fosters collaborative investigative work. Team members 

bring different perspectives to the investigation. All contribute to the 

identification of evidence, all contribute to the formulation of hypotheses, 

and all contribute to hypothesis testing. This type of teamwork does not 

happen automatically. Rather, it requires an investigation culture that 

encourages both inductive and deductive reasoning by all members of the 

team. 

Investigation teams also provide the opportunity to counteract biases of the 

individual investigators. The collegial interaction of team members can act 

to minimize individual biases. At the same time, there is a need to avoid 

the creation of team biases (groupthink). The diversity of thought and 

perspective need to be encouraged and nurtured by team management. 

● Recommendation: Fire and explosion investigation units should operate 

using a team approach. Cooperative investigation task force arrangements 

with neighboring jurisdictions, with state-level agencies, and with ATF 

should be organized and supported.

6-3. Mitigating Bias 

Human judgment is subject to many different types of bias. Sometimes the 

analysis might be affected by unwarranted assumptions and a degree of 
91

overconfidence that the investigator does not even recognize. Such 

cognitive biases are not the result of character flaws; instead, they are 

common features of decision making. A common cognitive bias is the 

tendency for conclusions to be affected by how a question is framed or how 

data are presented. Other cognitive biases may be traced to common 

imperfections in our reasoning ability.

Bias is well known in science, and significant effort has been devoted to 

understanding and mitigating bias. The goal is to make scientific 

investigations as objective as possible, so the results do not depend on the 

investigator. Avoiding, or mitigating, bias is an important task.

NFPA 921 discusses two sources of contextual bias: expectation and 

confirmation. Proper application of the scientific method as well as critical 

review of an investigator’s conclusions are important tools in mitigating 

potential bias.

Expectation bias arises when investigators reach premature conclusions. By 

not collecting and examining all of the relevant data, or by relying on 

irrelevant data, an investigator can form invalid conclusions. The tendency 

then is to disregard new or inconsistent data by “explaining it away.” 

Avoiding expectation bias first requires the investigator to identify all the 

available data. The investigator then needs to collect all that data and 

analyze all the data before developing and testing his hypothesis. In other 

words, properly following the scientific method.

Confirmation bias occurs when an investigator lapses into seeking to prove 

rather than refute a hypothesis. As the scientific method dictates, testing of 

the hypothesis should be designed to disprove that hypothesis. This testing 

needs to be sufficiently rigorous to discriminate among competing 

hypotheses.

Motivational bias is a discrepancy, usually conscious, motivated by one’s 

personal situation. Such biases can be introduced by organizational 

objectives and culture, or by stakeholder expectations. Fire investigators 

often work directly for organizations or clients that may have biases for 

certain outcomes. There is general acceptance that forensic experts, 
92

including fire investigators, should be shielded from influence from 

stakeholder expectations.

In civil proceedings, these sources for potential bias are offset by extensive 

disclosure requirements and depositions. In civil proceedings, experts from 

both sides are required to reveal their opinions and the underlying analysis 

so that judges can perform their gatekeeper duties prior to trial.

In criminal proceedings, the scientific experts, which includes the fire 

investigators, have much less rigid disclosure requirements which make it 

more difficult for judges to perform their gatekeeper duties. Experts for the 

prosecution are typically required to provide reports, but in some 

jurisdictions, are not required to provide them until after they testify on 

direct examination. Unfortunately, there is sometimes insufficient detail in 

the prosecution expert reports to explain how the opinion was arrived at, 

which limits the defense’s ability to challenge the result. Experts for the 

defense often provide no report or only a brief summary, which provides 

no opportunity to challenge the bases of their opinions. Even when reports 

are provided to the opposing side for review, it is common practice for 

experts to opine during trial about things that were not mentioned in their 

reports. This is particularly common when attorneys fail to conduct due 

diligence and judges fail to perform their gatekeeping function.

To guard against presumptions and mitigate bias, there is a need to 

consider only data that are relevant to the current task (see NCFS [2016]

concerning the need to limit data considered to that which is relevant to the 

current task). If the task is the determination of origin and cause of the fire, 

then relevant data includes information about the fire scene and the actions 

that occurred at the fire scene. The data may relate to the fire scene and 

actions before the fire, during the fire, and after the fire. The data may be 

physical or may be an action or observation. The relevance relates to the 

value of the data in determining where the fire originated, how it was 

caused, or how the fire developed. 

Task-irrelevant data, as it pertains to origin and cause determination, often 

relate to motives. Financial, criminal history, social relationship stress, 

evasive, or deceptive behavior information are not relevant to the 
93

determination of the origin or cause of a fire. Table 6-1 provides examples 

of data that are relevant to origin and cause determination and examples of 

data sources of potentially task irrelevant data for origin and cause 

determination .

Table 6-2: Task relevant data and sources of potentially irrelevant data for origin 

and cause determination. Irrelevant data are generally related to motives.

Data Sources that usually do not 

include task irrelevant data

Data Sources that may 

potentially include task 

irrelevant data

Firefighters’ observations 

relevant to the fire, scene security, 

and suppression activities 

Witness observations and 

photos/videos relevant to the fire 

and building contents

Occupancy 

History of defects 

Weather data 

Pre-fire activities on the scene

Ignitable liquid location 

Physical condition of the fire 

scene

Utilities 

Victim injuries

Financial records

History of fires

Criminal record

Claim file 

Marital strife 

Social media commentary 

Gossip 

Motive issues

Financial strife 

House for sale – real estate 

activity 

Indications of deception or 

emotional state of the victim 

Personal records
94

Security, detection, and alarm 

systems

Overpressure damage 

It is sound practice for the fire investigator to initially only consider data 

needed for an origin and cause determination. Shielding the fire 

investigator from information not directly relevant to the origin and cause 

of the fire has been suggested as one way that this can be accomplished 

[Lentini 2008]. When resources exist, other investigators should be 

assigned to develop “non-scene” data, including interviewing witnesses. 

Witness information relevant to the fire can then be presented to the fire 

investigator. When fire investigators are working alone, they need to use 

care in the sequence in which data is collected and analyzed. To the extent 

possible, the fire investigator should collect data directly related to the 

origin and cause first. 

Physical evidence, including samples for laboratory analysis, should be 

marked with information to identify the sample unambiguously and with 

the information the scientist requires to carry out their forensic analysis. 

Evidence markings should not include extraneous information that a 

forensic scientist does not need to perform the analysis. For example, a 

laboratory chemist doing ignitable liquid analyses does not need to know 

why a sample was taken for analysis. Whether the sample was taken due to 

a canine alert or some pattern evidence observed by the investigator are 

wholly irrelevant data for the chemist.20 Conversely, knowledge of the 

substrate and the existence of a comparison sample is relevant.

There are methods available to allow the collection of all data while 

screening the data for relevance before providing it to the fire 

investigator(s) determining origin and cause [Lentini 2008, Lentini 2015]. 

Because most irrelevant data arises out of non-scene data, a portion of the 

20 On the other hand, someone should be responsible for comparing canine alerts to 

laboratory confirmations and keeping that data available so canine performance on 

actual fire scenes can be assessed.
95

job of an investigation manager21 is to manage the flow of information. 

During this process, data not relevant to the origin, cause, and 

development of the fire can be screened from the investigator(s) making 

these determinations. In other circumstances, the method of sequential 

unmasking of data can be formally or informally implemented. A simple, 

informal application of sequential unmasking is conducting the fire scene 

examination before police interviews with neighbors are shared with the 

fire investigator. A downside of these methods is that they require 

additional personnel and resources during the active portions of the 

investigation that are not always available in today’s fire investigation 

units.

Technical reviews of the work product should be performed. These reviews 

are a way to identify other potential hypotheses and further test the 

hypotheses. Technical reviews can also identify and mitigate bias [NFPA 

921, §4.6.2]. While it may not be possible to shield the fire investigator from 

all information that is irrelevant for the origin and cause determination, it 

is possible to provide the technical reviewer with only the relevant data 

and therefore allow the reviewer to evaluate if the same determination 

would have been achieved with only relevant information.

● Recommendation: Fire and explosion investigation units should 

implement practices to minimize potential bias by using such processes as 

rigorous adherence to the scientific method, a technical review process, and 

processes to limit the exposure of investigators to biasing information.

6-4 Reporting Results of the Fire and Explosion Investigation 

Writing is thinking. To write well is to think clearly.

That’s why it’s so hard. David McCullough

The report in a fire investigation is much more than documentation; it is a 

part of the analytical process. As historian David McCullough has noted, 

21 Investigation manager or a case manager –primary role of limiting the task irrelevant 

data provided to the fire investigator, whose primary role is origin and cause 

determination. 
96

“Writing is thinking.” Writing is a discipline that forces you to examine 

your assumptions and challenge your reasoning. Even the anticipation of 

writing the report has a beneficial effect on data collection, hypothesis 

formation, and hypothesis testing. 

For many, writing the report is onerous and the least desirable aspect of the 

fire investigation. The temptation is to draft a short narrative report instead 

of a comprehensive report. Investigators would do well to remember a 

widely used saying, “If you didn’t write it, you didn’t do it.” A short 

narrative report may indicate that an investigation was a cursory affair.

The existing guidance on writing fire investigation reports is modest. 

NFPA 921 has Section 16.5 which runs about half a page. There is more 

general guidance for forensic reports such as ASTM E620, Standard Practice 

for Reporting Opinions of Scientific or Technical Experts [2018]. Formats of 

reports vary by the investigation unit and by the intended audience. 

Fortunately, deciding on the structure and content of a fire investigation 

report is a fairly straightforward exercise.

A fire investigation report needs to begin with simple descriptive material 

about the fire location and date, along with a statement of the purpose of 

the investigation. Most often this is to determine the origin and cause of the 

fire, but it may have the goal of assessing how and why the fire spread 

subsequently, or how the fire interacted with building systems to cause the 

resultant damage. 

Early in the report, there is a need to describe the property to provide 

information about the site. The construction type, the occupancy, and basic 

contents of the building are required. Site plans, floor plans, and pre-fire 

photographs are all helpful. Building contents, layout, and building 

systems are described. The degree of detail required varies with the fire 

situation and building. Documenting a security system that was not in use 

at the time or details of a part of the building not involved in the fire and 

smoke movement may not be required. The fire incident will dictate where 

the most detail is required.
97

The report should include a section on the circumstances surrounding the 

fire, including when and how the fire was discovered, and information 

about the fire suppression and rescue operations. These will generally 

provide some important timeline data along with important witness 

information about the fire. Most often, information that results from 

detailed interviews is not included in this early descriptive information. It 

generally portrays the knowledge of the fire incident before the 

investigation begins.

The report needs to include relevant data collected during the 

investigation. This includes data collected at the fire scene, data from 

interviews, as well as other sources of data such as fire department or 

building department documentation. It is common to summarize data 

elements in the report and provide the full data documentation in an 

accompanying file or appendix to the report. All relevant data should be 

included in the report, both data that is consistent and inconsistent with an 

investigator’s origin and cause hypothesis. Discarding or ignoring 

inconsistent data can lead to faulty conclusions. Data collection should 

normally be separated from data analysis in the report. 

The origin determination analysis needs to be described in detail. All origin 

hypotheses that arise out of the data need to be articulated. Each origin 

hypothesis needs to be subjected to rigorous testing fully described in the 

report. The results of the testing that led to the ultimate origin 

determination need to be described. 

Once the area of origin is established, all potential ignition sources need to 

be considered and used to develop cause hypotheses. In rooms that have 

been fully involved for more than a few minutes, every potential ignition 

source within the room should be hypothesized and tested as a cause. All 

cause hypotheses need to be described in the report. The testing of each of 

these hypotheses needs to be addressed in the report. The report needs to 

identify the hypotheses that survive the testing process and report the 

findings concerning the fire cause.

The reasoning associated with the origin and the cause hypothesis testing 

should be fully described. Information sources in the forensic and fire 
98

science literature used in hypothesis testing should be cited in the report 

and included in a reference list. Sections of NFPA 921 used in the 

investigation should be directly cited in the report.

As the above discussion demonstrates, writing an origin and cause report 

is an extensive process involving documentation, analytical thinking, and 

complete disclosure. All elements of the scientific method as employed in 

the investigation are fully described and discussed. The goal is to provide 

sufficient detail that readers can reproduce for themselves the reasoning 

from data to conclusions. The reader should be able to assess the level of 

significance of each piece of data, to independently test each hypothesis, 

and to reach independent conclusions. 

There are normally additional materials cited by the origin and cause 

report that may appear as appendices or independent cited documents. 

These include photos and accompanying photo logs, laboratory reports, 

diagrams, sketches, physical evidence, laboratory or field notes, and 

modeling files. In essence, the entirety of the investigative file should be 

included in the report or accompanying cited files or documents.

An origin and cause report is much like the investigation itself in that it is 

often a team effort. All the contributors to the report should be identified. It 

is common for individual contributors to write independent reports 

covering their portion of the investigation. When this approach is taken, 

the main report needs to summarize the component reports and cite the 

component reports for the complete description of the work.

As with any work product, an origin and cause report should be 

technically and administratively reviewed according to the policies and 

procedures of the fire and explosion investigation unit. The goal of these 

reviews is to assure completeness, clarity, and technical quality. 

Organization and operation of fire investigation units to support quality 

investigations is considered in detail in Chapter 8. 

In the end, it is the responsibility of all stakeholders (investigators, 

managers, lawyers, judges, insurance companies) to prepare and cause to 

be prepared complete and comprehensive fire and explosion investigation 
99

reports reflecting the best fire science, analyzed using the scientific method. 

As long as the industry accepts inferior fire and explosion investigation 

reports, the promise of modern fire and explosion investigation science and 

technology will not be realized.

There are challenges in the criminal justice system that impede 

accountability for the quality of fire and explosion investigation reports 

used in legal proceedings such as:

o inadequate counsel for defendants, 

o inadequate funding for experts,

o judges not requiring reliability hearings to evaluate the expertise and 

methodology of the experts testifying in court, 

o judges being ill-prepared to assess the adequacy of a fire and 

explosion investigation report, and as a result not embracing their

“gatekeeping” function for science in the courtroom, and

o prosecutors and defense attorneys not being familiar with fire 

investigation best practices.

● Recommendation: Fire and explosion investigation reports should include 

all data collected, all hypotheses formulated, details of the testing process for 

each hypothesis, and the conclusions of the investigation. 

● Recommendation – In a case where an incendiary fire cause has been 

alleged, the origin and cause of the fire should be thoroughly explored 

through discovery or evidentiary hearings

● Recommendation – Judges and lawyers should be educated and trained on 

fire investigation (see also the NCFS [2015] recommendation, 

Recommendation to the Attorney General Forensic Science Curriculum 

Development)

● Recommendation: All stakeholders (investigators, managers, lawyers, 

judges, insurance companies) must take responsibility for requiring 

complete and comprehensive fire and explosion investigation reports.
100

REFERENCES

ATF (2016), Fact Sheet - National and International Response Team, 

https://www.atf.gov/resource-center/fact-sheet/fact-sheet-national-andinternational-response-team

ATF (2016a), ATF's National Response Team; How ATF Assists State/Local 

Law Enforcement and Fire Agencies, 

https://www.atf.gov/resource-center/fact-sheet/fact-sheet-national-andinternational-response-team

Lentini, J (2008) Toward a More Scientific Determination: Minimizing 

Expectation Bias in Fire Investigations. International Symposium on Fire 

Investigation, Investigations Institute. 

https://drive.google.com/drive/folders/1d_V2v8q8fkWAmsxCD3icf6QiLYziR47

Lentini, J (2015) Contextual Bias in Fire Investigations: Scientific vs 

Investigative Data, The Brief, American Bar Association, Tort Trial and 

Insurance Practice Section, 44 ( 3). 

https://storage.googleapis.com/production-constantcontact-v1-0-

7/507/175507/IaE9rCjE/8471dae61f1346e8b11abd83c03edb2e?fileName=2

015%20Contextual%20Bias%20in%20Fire%20Investigations%20Scientific%2

0Investigative%20Data.pdf

Gorbett, G., Meacham, B., Wood, C., Dembsey, N. (2017). “Structure and 

Evaluation of the Process for Origin Determination in Compartment Fires.” 

Fire Technology, January 2017, Volume 53, Issue 1, pp 301–327 

https://link.springer.com/article/10.1007/s10694-015-0553-3

IAAI (2017), The Team Concept, Duties and Responsibilities, Interfire 

Online. 

http://www.interfire.org/res_file/team.asp
101

National Commission on Forensic Science (2017), Work Products of the 

FCFS, https://www.justice.gov/archives/ncfs/work-products-adoptedcommission

NFPA (2017): Guide for Fire and Explosion Investigations, NFPA 921, Quincy, 

MA. 

http://www.nfpa.org/codes-and-standards/all-codes-and-standards/listof-codes-and-standards?mode=code&code=921
102

7. RESEARCH NEEDS IN FIRE AND EXPLOSION

INVESTIGATION

7-1 The Current State

Fire investigation, like many other forensic science disciplines, suffers from 

an inadequate research base. Much of the research conducted into fire 

phenomena has developed over the last fifty years and was primarily 

aimed at understanding factors related to fuels and the development of 

fires in compartments. This research was driven by a desire to improve fire 

safety rather than being focused on determining the origin and cause of 

fires. Much of the study related to fire investigation has been conducted on 

a more or less ad hoc basis to understand issues related to a particular fire 

rather than to understand the broader nature of fire investigation 

methodologies.

As discussed in Chapter 4, fire investigation is generally thought of as a 

two-step process. The first step is to determine the origin (where the fire 

started), and the second step is to determine the cause (how and why the 

fire started). Unless there is a reliable human witness or electronic monitor, 

origin determination is based largely upon the investigator’s interpretation 

of the effects of the fire and the patterns those effects create. Cause 

determination involves the analysis of fuels and the interaction of those 

fuels with heat sources.

The determination of fire origin is based largely on the analysis of the 

damage caused by the fire. At times, fire investigators interpret the 

patterns left by the fire without a rigorous scientific understanding of the 

nature of fire patterns as well as when and how those patterns were 

created. The science underpinning our understanding of the nature of fuels 

and the reaction of fuels to heat (fire effect) is more fully developed. 

Various procedures, protocols, and methods have been developed and can 

be used by fire investigators to assist in reaching conclusions about origin 

and cause. Within the fire investigation discipline, there is currently little 
103

rigorous scientific study establishing the strengths and limitations of 

various methods and procedures. There is also little information to identify 

sources of bias and the impact of variations in these processes. Existing 

guidance in NFPA 921 does not fully address the uncertainty, repeatability, 

and limitations of the current methodologies.

Between 2007 and 2017, The National Institute of Justice (NIJ) had awarded 

19 grants for research in the area of “Arson.” Half of these grants were 

specifically related to analyzing ignitable liquid residue, a laboratory 

endeavor. The remaining focused on discrete elements related to fire 

investigation.

A broader focus on those key datasets most often relied upon by fire 

investigators is needed in research. The results of that research need to be 

translated into practical tools that can be employed by investigators at fire 

scenes. 

7-2 Establishing a Research Agenda

The National Commission on Forensic Science [NCFS 2017] has provided a 

number of recommendations for the need for further scientific inquiry and 

research in support of forensic science. In order to guide research in fire 

and explosion investigation, there is a need to establish a research agenda 

in the field that can assist funding agencies in setting priorities and 

motivate investigators to examine the most critical needs of the profession.

Two broad areas of research needs have been identified. One deals with the 

validation of origin and cause determination protocols. The need here is for 

comprehensive, statistically sound assessments of current methodologies 

and the identification of new methodologies. The other area involves 

reducing the potential for bias in fire and explosion investigations. The 

need here is for methods and protocols to reduce bias associated with data 

collected by a fire investigator that is irrelevant to the determination of 

origin and cause.
104

Regarding origin determination, NFPA 921 identifies various techniques 

for analyzing and interpreting damage (fire effects and patterns). These 

include heat and flame vector analysis, depth of char analysis, depth of 

calcination surveys, electric arc surveys, and origin matrix analysis. Vector 

analysis and depth of char were discussed in the first edition of NFPA 921 

in 1992. Arc surveys were introduced in the 2001 edition of the document 

and origin matrix analysis first appeared in the 2017 edition. Each of these 

techniques has been the subject of varying degrees of study, and the results 

have been published in the fire investigation literature. There is 

considerable variability in the techniques used in these analyses. None of 

these techniques has been fully validated. Changes in manufacturing 

processes (e.g., lightweight gypsum wallboard) may impact the validity of 

depth of calcination surveys. The wider use of arc fault circuit interrupters 

will likely impact arc surveys. Ongoing research is needed to assure that 

methods remain viable as technologies evolve.

Fire investigators collect data that may be found to be irrelevant to the 

origin and cause determination. This data may bias an investigator’s origin 

and cause conclusions. Research is needed on methods and procedures to 

manage this information and to limit its impact.

● Recommendation: The Research Agenda developed below should be 

adopted by research funding agencies and should be carried out over the next 

several years.

The Research Agenda Items outlined below are purposely broad in 

identifying general categories of needed research. It is expected that each 

recommendation will result in numerous discrete research projects. 

7-2.1 Origin Determination

Concerning origin determination, NFPA 921 identifies three general 

categories of information from which data can be gathered and analyzed to 

form the basis for origin conclusions. These are fire patterns, including arc 

mapping, witnesses and electronic information, and fire dynamics analysis. 
105

Research is needed in each of these areas to enhance the science of fire 

investigation.

Information on the properties of fuels, the characteristics of heat sources, 

and the interaction of the two is important in the determination of fire 

cause. Much of this information comes from fundamental fire dynamics 

research. 

Fire Patterns 

Fire investigators almost always base their origin determination on the 

interpretation and analysis of fire patterns. For the conclusions to be 

reliable, the investigator must have an understanding, based on fire 

dynamics, of when during the fire, those patterns were created. The 

investigator must also understand how those patterns were created – a fire 

plume, a hot gas layer, and the effects of ventilation, flashover, and 

suppression. 

The study of mechanisms that produce fire effects and patterns is one area 

of research needed. Over eighty years of research related to fire patterns 

have been compiled and provided in a recent publication [Gorbett et al. 

2015]. Additional work on the effects of ventilation on pattern production 

with varying room and ventilation opening configurations are important to 

validating pattern analysis methods. 

In most room fires, the patterns of interest are created on surfaces — floors, 

walls, contents, and ceilings. Changes in materials of these surfaces affect 

pattern creation. Research is needed to understand further the effect that 

material properties have on the nature of the pattern creation.

Post-fire, many patterns exist within a building and the room of origin. It is 

the accumulation of patterns and the relationship of patterns, rather than a 

single pattern, that need to be analyzed. There has been little research on 

methodologies and procedures to assist the fire investigator with assigning 

meaning to a broad array of patterns.
106

Research Agenda Item #1 - Develop a coordinated research program to analyze 

the effects that ventilation has on the creation and obscuration of fire patterns 

related to the origin of a fire.

This is of high priority. The impact on fire investigations is significant.

Doors, windows, and other openings in a compartment introduce air, allow 

the escape of heat and thus affect temperatures and flow patterns. 

Temperature and flow, in turn, create and destroy patterns on the 

compartment surfaces. Given the influence of these factors, a pattern that is 

observed post-fire may or may not be related to the origin. Without a solid 

understanding of these effects, fire investigators may misinterpret these 

patterns, thus making an erroneous conclusion about the origin of a fire.

The ATF has published information on a procedure called “Origin Matrix 

Analysis” that was introduced in 2013 and incorporated into the 2017 

edition of NFPA 921. Much more work is needed in compartments of 

various sizes with a combination of vents to refine this technique further 

and to translate the research into information that can be applied by the fire 

investigator.

A prototype process called the “Process for Origin Determination” was 

published [Gorbett et al. 2017]. This process evaluated fire damage in the 

context of what compartment fire dynamics caused the damage. To date, 

this is the only procedure to have published findings as to its effectiveness 

at increasing reliability and validity of its use with practitioners. 

Research Agenda Item #2 –Develop a coordinated research program to analyze 

the effect that material properties have on the nature of the pattern creation. 

This is of medium priority. The impact on the conclusions made by fire 

investigators could be significant as changes are made in the substrate and 

finish materials.

Almost all of the guidance on wall and ceiling patterns in NFPA 921 is 

based on those surfaces being unpainted gypsum wallboard available at 

the time of the testing. Fire investigators must understand that their 
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analysis and interpretation of patterns may change as the material on 

which those patterns manifest themselves change. The effects that are 

created on surfaces other than this material are largely unknown. Research 

is particularly needed on how residential construction methods and 

practices have changed and the attendant impact on using fire patterns to 

determine fire origin.

Research Agenda Item #3 – Require that fire investigation be a component in 

future public funding of compartment fire research. 

Research Agenda Item #4 – Encourage fire research organizations currently 

conducting compartment fire research to include fire investigation components in 

those fire tests. 

This is of high priority. The impact could be significant. 

Over the last several years a series of full-scale tests in laboratory 

constructed compartments and formerly occupied buildings has been 

conducted. Additional testing is planned. The ability to use buildings for 

testing is of great value because such testing presents the most realistic 

conditions possible. Testing programs such as these should be expanded so 

that as data is gathered and analyzed. The research can benefit the fire 

investigation community. The proposed research would not interfere with 

planned research goals as the data gathering would be conducted after the 

fire test. 

Public funding for these programs should require that fire investigation be 

a component of compartment fire research. 

Research Agenda Item #5 – Investigate the impact of room size on the generation 

of patterns and the validity of using those patterns for origin determination.

This is of medium priority. The impact is significant if the current trend in 

residential housing construction continues.

In the last twenty years or so, the trend in single-family home construction 

has been to move away from small rooms low in height to larger open 
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areas with high ceilings. A home today may have the living area on the 

ground floor constructed as one large open area without walls separating 

functional spaces. Sleeping areas may be large suites rather than individual 

bedrooms and bathrooms. Most of the research on patterns has been 

conducted in “typical” size rooms; for example, ten feet by twelve feet by 

eight feet in height. Research is needed in larger spaces with modern 

furnishings to identify this impact on patterns.

Research Agenda Item #6 – Develop protocols, techniques, and instrumentation to 

conduct measurements to quantify fire patterns reliably. Evaluate the reliability 

and validity of these techniques as measurable tools for pattern analysis in the 

process of origin determination.

This is of high priority. The impact depends upon the usefulness of the 

techniques.

Most fire investigators currently rely on subjective analysis of fire patterns. 

Measurable techniques for analyzing fire patterns would improve the 

reliability and validity of using this data to determine fire origin.

NFPA 921 has information on calcination and char depth measurements as 

a tool to assist in origin determination. Many consider these techniques to 

be imprecise and of questionable value. They are not employed by most 

fire investigators because of the time required and because of a lack of 

perceived usefulness. Additionally, there is little data on how differences in 

the material composition of construction components such as gypsum 

wallboard may impact these techniques. 

Results of this research need to be reported in such a way that it is practical 

and usable by the fire investigator. The protocols and techniques 

developed need to be in a form that supports the analysis of fire growth in 

the compartment. 

Arc Mapping

Locating and interpreting electric arc damage on components of building 

electrical systems has been recognized as an origin determination tool for 
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over twenty years. It has been included in NFPA 921 since 2001. The theory 

and technique of this method are based upon the wiring methods and 

components that were used in the past. As new techniques and 

components are used in building electrical systems, the creation of arc 

damage from a fire and the implications of that damage to origin 

determination need to be reevaluated. 

Research Agenda Item #7 – Develop a coordinated research program to analyze the 

effects that electrical equipment such as ground-fault circuit interrupters (GFCI) 

and arc-fault circuit (AFCI) interrupters have on the process of arc-mapping.

This is of medium priority. The impact is significant.

Arguably, the process of identifying and mapping areas of electrical 

activity (arcing) on conductors and using that information as data in origin 

determination is an effect (and thus a pattern) of a fire. Arc mapping has 

been identified as important origin data since its inclusion in the 2001 

edition of NFPA 921. Research to date has shown that arc mapping is a 

valid tool in origin determination. There has been little research into the 

impact that GFCIs and AFCIs have on the creation of arcs and the resultant 

damage to copper conductors. Fire investigators need to understand the 

importance of considering such impacts on the analysis of arc damage data.

Witness Information and Electronic Data

Research Agenda Item #8 – Develop protocols or techniques for collecting, 

extracting, and analyzing data from the variety of witnesses from a fire scene (e.g., 

eyewitnesses, first responders, and owners). 

Fire investigators are well informed on the need to develop information 

from those who first observe the fire and from those who subsequently 

arrive to extinguish the fire. Fire investigators also are aware of the 

importance of gathering information from those familiar with the pre-fire 

conditions like the layout of furnishings and appliances in the room of 

origin. Training is common on how to conduct such interviews but 

uncommon on how to accurately use the information for origin 
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determination. There is no specific process outlined within NFPA 921 for 

the use of eyewitness information. 

This is of medium priority. The impact is significant.

Most also recognize the importance of information from security cameras 

and alarm systems.

Data from “internet-of-things” devices that might be stored within the 

device at the fire scene, at some remote storage location, or in the cloud can 

provide significant insight into fire origin and spread.

Research Agenda Item #9 – Develop awareness of methods for collecting, 

extracting, and analyzing data from the variety of electronic sources now finding 

their way into residential and commercial buildings.

This is of medium priority. Currently, the significance is low but, as these 

devices become more commonplace, the significance will likely increase. 

Fire investigators need to understand the type of information that might be 

available and how to access that information. Given the potential 

evidentiary value, investigators need to understand the issue of protection 

and preservation of this information. Aside from a brief mention, there is 

no information on this topic currently in NFPA 921.

Fire Dynamics

The performance of fuels on the ignition and the subsequent growth and 

spread of the fire impacts an investigator’s determination of both fire origin 

and fire cause. Critical fuel characteristics, such as ignition temperature, are 

not well understood and not appropriately applied by many fire 

investigators. Mechanisms of ignition are misinterpreted because of a lack 

of understanding of heat transfer. Most of this is well documented in the 

fire science literature and well understood by fire scientists.

Research Agenda Item #10 – Develop practical tools that can be used by the fire 

investigator to evaluate fuel characteristics and the performance of fuels under fire 
111

conditions in support of understanding fire growth as it relates to the 

determination of origin.

This is of medium priority. The impact is significant.

The primary characteristic of fuels used by fire investigators today is 

ignition temperature. These temperatures are published for many fuels in a 

variety of sources. Often the temperature is reported as a discrete number. 

In evaluating fire cause, fire investigators often misapply the concept of 

ignition temperature when evaluating the viability of a fuel given a known 

heat source. Ignition temperature, however, is less important when 

evaluating ignition source or fuel competency than critical heat flux, the 

minimum heat flux that can cause ignition. This is a concept with which 

many investigators need to become more conversant. Heat release rates of 

common materials and fuel packages are required to support fire growth 

analyses. Fuel characteristics need to be cataloged and reported in a way 

that can be used validly by fire investigators. 

7-2.2 Cause Determination

New technologies and products coming to market have always presented 

new challenges to the fire investigation community in identifying the cause 

of fires. In recent years, one of the most widely reported issues with a new 

product causing fires is lithium-ion batteries. As this battery technology 

advanced and became more viable, these types of batteries found their way 

into a wide variety of products. Fire incidents were reported to the CPSC, 

and several products have been recalled.

Research Agenda Item #11 – Require manufacturers reporting recalls and the 

CPSC to make available data that is developed in determining a product recall that 

identifies the failure mechanism.

This is of high priority. The impact is significant.

Information reported to the public by CPSC is generally not specific as to 

the mechanism of failure. Many fire investigators assume that just because 
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a product is recalled, it is the likely ignition source if found in the area of 

origin in a particular fire. By providing detail on the failure mechanisms 

and circumstances required for a fire to occur, the quality and validity of 

cause determination would be enhanced. By improving the quality and 

validity of cause determinations, the fire investigation community could 

provide enhanced feedback to CPSC and manufacturers. 

7-3 Getting Research into Practice

Publicly funded fire investigation research is critical to get that research 

into practice. Many times, fire investigation research is conducted privately 

to support a particular investigation with pending litigation. This research 

is seldom published. Most fire investigators are practitioners rather than 

researchers. State and local public agencies or small private companies 

most often do not have the resources to conduct testing. Research grants 

targeting fire investigation by government entities such as NIJ and fire 

investigation research projects undertaken by government fire research 

laboratories at NIST and ATF would substantially contribute to the 

discipline. 

The results of research should be published in a forum available to fire 

investigators in a form useful to practitioners. The goal should be getting 

the research results into practice by communicating to the fire investigation 

community via trade publications and educational seminars. Consideration 

should be given to the fact that NFPA 921 is updated on a three- or fouryear cycle. Getting information distributed to the fire investigation 

community via a new edition of NFPA 921 is not necessarily timely but 

publication in NFPA 921 gives new techniques a strong endorsement. 

Research Agenda Item #12 – Create an easily accessible repository for research 

on fire investigation.

This is of high priority. The impact is significant.

The Technical Committee charged with writing NFPA 921 works to include 

references to research in that document. Since the document is updated on 
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a three- or four-year cycle, references to new research are likely not 

included in that document. Federally funded research is reported in a 

variety of ways and can be found (many times not easily) in various online 

and printed sources. There should be a single online repository easily 

accessible to fire investigators where this research can be found.

Research Agenda Item #13 – Develop a mechanism for disseminating research 

conducted by the ATF Fire Research Laboratory.

This is of high priority. The impact is significant.

The ATF Fire Research Laboratory is the federal facility charged with 

conducting research specifically related to the investigation of fires. This 

research is not often disseminated. A mechanism needs to be developed so 

that this research can be disseminated in a timely fashion to the broader 

fire investigation community.

Research Agenda Item #14 – Require that federally funded research into fire 

phenomena that involves full-scale fire testing include a component to document 

post-fire conditions.

This is of high priority. The impact is significant.

Several federal agencies conduct or fund full-scale fire research for various 

purposes other than fire investigations. Many times, the post-test 

conditions are not documented or evaluated. This is lost information from 

a test that is costly to conduct. Requiring that the post-fire conditions, such 

as patterns, be documented and disseminated for use by the fire 

investigation community will help to make the most of such tests. 

Research Agenda Item #15 – Develop techniques to limit the exposure of fire 

investigators to potentially biasing information that can be practically applied 

during a fire investigation.

Research Agenda Item #16 – Develop techniques to identify and manage bias in 

the development of conclusion by fire investigators.
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These are of high priority. The impact is significant.

It is sound practice for the fire investigator to initially only consider data 

needed for an origin and cause determination. Shielding the fire 

investigator from information not directly relevant to the origin and cause 

of the fire has been suggested as one way that this can be accomplished. 

The practicality of various shielding techniques has been debated with the 

fire investigation community.

Research is needed to develop processes and application techniques for fire 

investigators to use in identifying and collecting data solely relevant to 

origin and cause determinations.

Research is also needed in the development of procedures to be used by 

fire investigation units to use in identifying and controlling bias before 

origin and cause conclusions are finalized.

7-4 Conclusions

The research needs of the fire investigation community are constantly 

evolving as the nature of the structures within which fires occur changes 

and as the nature of the materials that burn changes. Funding for research 

in the area of fire investigation is extremely limited. Research funding 

needs to be increased and sustained to support these investigation needs. 

Because of the diverse interests involved in fire investigation, there needs 

to be a mechanism to evaluate, prioritize, and coordinate research. It is 

important that a group of practitioners representing a variety of interests as 

represented by this OSAC Subcommittee have regular input on an ongoing 

basis. This Subcommittee desires that those applying for fire investigation 

research grants look to these recommendations for areas of need. It is also 

the desire of this Subcommittee that those funding such research give 

priority to proposals in these areas.
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Research Agenda

#1 - Develop a coordinated research program to analyze the effects that ventilation 

has on the creation and obscuration of fire patterns related to the origin of a fire.

#2 –Develop a coordinated research program to analyze the effect that material 

properties have on the nature of the pattern creation. 

#3 – Require that fire investigation be a component in future public funding of 

compartment fire research.

#4 – Encourage fire research organizations currently conducting compartment fire 

research to include fire investigation components in those fire tests. 

#5 – Investigate the impact of room size on the generation of patterns and the 

validity of using those patterns for origin determination.

#6 – Develop protocols, techniques, and instrumentation to conduct measurements 

to quantify fire patterns reliably. Evaluate the reliability and validity of these 

techniques as measurable tools for pattern analysis in the process of origin 

determination.

#7 – Develop a coordinated research program to analyze the effects that electrical 

equipment such as ground-fault circuit interrupters (GFCI) and arc-fault circuit 

(AFCI) interrupters have on the process of arc-mapping.

#8 – Develop protocols or techniques for collecting, extracting, and analyzing data 

from the variety of witnesses from a fire scene (e.g., eyewitnesses, first responders, 

and owners). 

#9 – Develop awareness of methods for collecting, extracting, and analyzing data 

from the variety of electronic sources now finding their way into residential and 

commercial buildings.

#10 – Develop practical tools that can be used by the fire investigator to evaluate 

fuel characteristics and the performance of fuels under fire conditions in support of 

understanding fire growth as it relates to the determination of origin.
116

#11 – Require manufacturers reporting recalls and the CPSC to make available 

data that is developed in determining a product recall that identifies the failure

mechanism.

#12 – Create an easily accessible repository for research on fire investigation.

#13 – Develop a mechanism for disseminating research conducted by the ATF Fire 

Research Laboratory.

#14 – Require that federally funded research into fire phenomena that involves 

full-scale fire testing include a component to document post-fire conditions.

#15 – Develop techniques to limit the exposure of fire investigators to potentially 

biasing information that can be practically applied during a field investigation.

#16 – Develop techniques to identify and manage bias in the development of 

conclusion by fire investigators.

REFERENCES

Gorbett, G., Meacham, B., Wood, C., Dembsey, N. (2017). “Structure and 

Evaluation of the Process for Origin Determination in Compartment Fires.” 

Fire Technology, January 2017, 53 (1), pp 301–327 

https://doi.org/10.1007/s10694-015-0553-3

National Commission on Forensic Science (2017), Work Products of the 

FCFS, 

https://www.justice.gov/archives/ncfs/work-products-adoptedcommission

NFPA (2021): Guide for Fire and Explosion Investigations, NFPA 921, 

Quincy, MA. 

http://www.nfpa.org/codes-and-standards/all-codes-and-standards/listof-codes-and-standards?mode=code&code=921
117

8. STRENGTHENING OVERSIGHT OF FIRE

AND EXPLOSION INVESTIGATION

PRACTICES

8-1 Certification of the Individual

As outlined in Chapter 2, many professions employ certifications that 

affirm that an individual has gone through a defined process of instruction, 

study, and testing, has agreed to a Code of Ethics and continuing 

professional development. The OSAC Fire and Explosion Investigation 

Subcommittee agrees with the National Commission on Forensic Science’s 

position that fire investigators, as forensic science practitioners, should 

become certified [NCFS 2016]. Any valid certification program requires the 

fire investigator to be re-certified periodically by maintaining a minimum 

number of continuing education hours.

The challenge is that simply being certified is not sufficient. There are 

numerous cases of certified fire investigators who deviate significantly and 

without justification from NFPA 921 and NFPA 1033 [Lentini 2017]. Fire 

investigators must consistently prove that they adhere to the current 

science in the profession, and the criminal justice system needs to require 

all participants in the fire investigation to comply with national best 

practices. 

● Recommendation: Certify fire investigators by a third party and obtain 

other credentials that ultimately enhance their knowledge.

Competency Testing vs. Proficiency Testing

Do fire investigators need competency testing, proficiency testing, or both? 

“A competency model is the traditional way to identify what needs to be 

included in a typical training program. A competency model breaks 

training elements down into three parts: Knowledge, Skills, and Abilities 

(KSAs). When building a competency model, one compiles a long list of 

training elements to include in training. This requires peer groups of 
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professionals to decide on the importance of and frequency of each KSA. 

The downside of this testing approach is that it often misses how 

competencies work together in different combinations to produce the 

desired result. A proficiency model, on the other hand, provides a 

completely different point of view. Proficiency is both a measure of 

performance and a set of observable behaviors that describe what a 

proficient investigator produces and how the investigator must work to 

achieve those results. Proficiency is a snapshot of what success looks like 

on the job. With a competency model, one can master all the competencies 

and not produce the desired results on the job. In other words, all the 

pieces do not add up to the whole. With a proficiency definition, the result 

is completely defined, and training does not end until the individual 

becomes proficient. The result is important rather than all the pieces and 

parts.” [Atwert, 2011].

Competency testing typically occurs for fire investigators when 

certifications are acquired. Proficiency testing is not common for most fire 

investigators. Fire investigators are certainly expected to follow the 

practices outlined in NFPA 921 and meet the qualification requirements of 

NFPA 1033. There are numerous training courses that fire investigators can 

take to acquire the knowledge of the sixteen topics required by NFPA 1033. 

The difficulty, as stated above, is how all the competencies work together 

to produce a fire investigator who performs in accordance with these two 

NFPA documents in their daily activities. Competency testing shows that 

the investigator at a point in time passed the exam and completed the 

training course. That is important, but the training and evaluation cannot 

stop there.

A proficiency model is an environment where the fire investigator is 

evaluated through their reports, trial or deposition performance, mock 

reliability hearings, reviews of investigations by independent third parties, 

and other processes that measure cumulative proficiency. Proficiency 

testing evaluates how the investigator utilized all their education, 

certifications, and training in the performance of their job as it relates to 

professional best practices. Proficiency evaluations of performance are not 

a regular function within most fire investigation organizations. This type of 
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evaluation needs to be as common as competency testing to encourage fire 

investigators in their professional development. 

● Recommendation: Require competency and proficiency testing for fire 

investigators both in their training and the continued monitoring of their 

work product. 

8-2 Accreditation of Certification Bodies

For certifications to have validity, they must be challenging to attain, and 

the entity that confers them must be reputable as well. The National 

Commission on Forensic Science (NCFS) has called for accreditation of 

certification bodies in all areas of forensic science (NCFS 2017). Typically, 

certifications originate from a governmental agency or professional 

association. The well-known certifications in the fire investigation 

profession were listed in Chapter 2. There are also accrediting groups that 

review the certifications conferred by governmental agencies, higher 

education institutions, and other groups. As an example, the National 

Board on Fire Service Professional Qualifications (Pro Board) accredits fire 

service certifying processes. “The accreditation process begins with the 

submission of an application, including a detailed self-study document, by 

the organization seeking accreditation. The application package is then 

reviewed by the members of the Committee on Accreditation (COA) for 

completeness and compliance with the accreditation criteria of the Pro 

Board. The next step is a site visit by a team of COA members, usually two, 

who perform an extensive on-site review of the organization’s testing and 

certification processes. The site visit team prepares a report and presents it 

to the COA. The COA decides if accreditation is granted.”

(http://www.theproboard.org/) 

The International Fire Service Accreditation Congress (IFSAC) also 

accredits certifying processes and higher education fire-related degree 

programs similar to the Pro Board. The Eastern Kentucky University Fire, 

Arson and Explosion Investigation Bachelor of Science degree is the only 

fire investigation degree program accredited by IFSAC as of 2021.
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Additionally, in response to a proliferation of forensic science certifications, 

the American Academy of Forensic Sciences (AAFS) incorporated the 

Forensic Specialties Accreditation Board (FSAB). The FSAB accredits ten 

certification programs, including the IAAI’s certification program. Criteria 

for FSAB accreditation include: 1) An application process with a credentials 

check; 2) an examination process with demonstrated technical merit; 3) a 

recertification component requiring continuing professional development 

and 4) a Code of Ethics with a mechanism for withdrawing certification 

from a certified individual who violates that Code of Ethics.

8-3 Accreditation of Fire Investigation Units

The National Commission on Forensic Science (NCFS) has called for the 

accreditation of all forensic science service providers [NCFS 2017]. They 

identify both the benefits and challenges in this process.

OSAC was established to review existing forensic science standards to 

identify or create best practices or new standards that forensic science 

practitioners need to adhere to in their daily operations to facilitate a better 

criminal justice system that relies on solid science. The standards and best 

practices approved by OSAC can then be incorporated into an accrediting 

program with performance measures that fire investigation organizations 

should follow to become accredited. 

Three well-known institutions accredit public safety organizations. The 

Law Enforcement Accreditation Program (LEAP) was established by the 

Commission on Accreditation for Law Enforcement Agencies (CALEA) to 

provide performance measures that law enforcement agencies can use to 

evaluate the operations of the organization. The Commission on Fire 

Accreditation International (CFAI) has developed performance evaluation 

categories for fire service organizations to conduct a self-assessment of 

their operations. CFAI defines accreditation as: 

“a comprehensive self-assessment and evaluation model that enables 

organizations to examine past, current, and future service levels and 
121

internal performance and compare them to industry best practices. This 

process leads to improved service delivery” [CFAI 2017]. 

CFAI has a programs category within the overall accreditation process that 

addresses a fire investigation division in a fire department. The 

accreditation envisioned by the OSAC subcommittee is substantially more 

in-depth than what is available there. 

As of 2021, there are four fire investigation agencies accredited to ISO/IEC 

17020 by the American Association for Laboratory Accreditation (A2LA) 

or the ANSI National Accreditation Board (ANAB). “The Forensic 

Examination accreditation program was developed for those organizations 

that perform examinations of an item or location and, based on 

professional judgment, make a determination of conformity with proposed 

events or known conditions. In reality, any inspection performed could 

ultimately be meant for use in court. For example, a manufacturer may 

request an inspection of a manufactured item to help improve their 

product, but another customer may request the same inspection with the 

ultimate aim of using the results in a civil trial. The work isn’t any 

different, but how one approaches the examination is. If the work is done 

incorrectly or if it is conducted by an untrained or incompetent employee, 

your report may be ruled inadmissible in court.” [A2LA 2017]

The OSAC Fire and Explosion Investigation Subcommittee plans to act as a 

resource in developing a common set of performance measures that all fire 

investigation organizations should use. In 2016, the Subcommittee 

proposed that NFPA develop a standard for the organization and 

operation of a fire investigation unit and developed a first draft of the 

standard. NFPA accepted this proposal in 2018, and an NFPA committee 

began its work in 2019. It is envisioned that the NFPA standard (NFPA 

1321) will be suitable as the basis document for accreditation of fire

investigation units. 

Stakeholders’ input will be sought to assist in this development. By 

creating a common set of performance measures to be utilized by all Fire 

Investigation Units, and supported by the judiciary, the profession can 

minimize the risk exposure of inadequate fire investigations.
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Overcoming Barriers for Fire Investigation Agencies to Become 

Accredited

It is well known that achieving accreditation is challenging in several 

respects. First, there must be a desire by senior leaders of the Fire 

Investigation Unit (FIU) to seek accredited status. To create this desire, 

some impetus in the form of an expectation by key stakeholders that the 

agency should be accredited needs to exist. The judiciary, prosecuting and 

defense attorneys, fire investigation associations, and others must set an 

expectation that operating without accreditation is outside the bounds of

best practice.

In most cases, agencies will need to create documented policies and 

procedures that comport with individual performance standards. This is 

normally accomplished by the adoption of a quality assurance program. 

This is very resource-intensive and requires staff to be assigned to work on 

these documents. Additionally, there will likely be performance measures 

that will require additional funding for training, acquiring certifications, 

case reviews, and other needs. Most fire investigation agencies have very 

few staff, and these members may be required to perform fire code 

inspections and other duties in addition to investigating fires. It will be 

challenging for these agencies to develop and document a QA program 

and become accredited. It may be necessary to hire additional personnel 

whose sole responsibility is the development and documentation of a QA 

system. One way to overcome the challenges is by partnering with other 

FIUs in a region and establishing a county or area-wide team to allow for

more staff to work on the accreditation project. The OSAC Fire and 

Explosion Investigation Subcommittee is currently developing a template 

Quality Manual complete with template Standard Operating Procedures 

and Guidelines for fire and explosion investigation units to facilitate FIUs 

developing the documentation needed for accreditation. 

It is vitally important that any fire investigation agency be compliant with 

best practices. Accreditation is an important component of validating that 

an agency is assuring that their investigators meet NFPA 1033 

requirements and investigate fires according to NFPA 921. An 
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accreditation process creates an environment of continuous improvement 

based on national consensus standard best practices. Additionally, once an 

agency achieves accreditation through this independent third-party

validation entity (the accrediting agency), the organization must submit 

annual reports on progress and be re-accredited in a defined period. Most 

agency accreditations last 4 or 5 years. This accountability is very 

important to ensure that the agency continuously meets the evolving 

performance measures in updated editions of the accreditation 

requirements. The continuous improvement process is ongoing. It is the 

OSAC Fire and Explosion Subcommittee’s vision that in time, accreditation 

will become the norm in fire investigation units. In some jurisdictions now, 

public and private laboratories that are not accredited are prevented from 

participating in the criminal justice system ( e.g., 

https://www.justice.gov/opa/pr/justice-department-announces-newaccreditation-policies-advance-forensic-science, 

http://www.txcourts.gov/fsc/accreditation/ ). 

● Recommendation: Require accreditation of fire investigation units by third 

parties based on an applicable consensus standard. 

8-4 Science Advisory Workgroup for Quality Control

This section reviews how the Texas State Fire Marshal’s Office instituted a 

multi-disciplinary panel of experts, retrospective case reviews, postconviction reviews, and working on a goal to establish proactive pre-trial 

case vetting to improve the quality of fire investigations. It provides a 

model for other fire investigation units.

Background

The Texas State Fire Marshal’s Office (SFMO) found itself in a very difficult 

place in 2009. In 2006, The Texas Forensic Science Commission (TFSC) 

accepted its first complaint, submitted by the Innocence Project in the cases 

of Cameron Todd Willingham and Ernest Ray Willis. Both men had been 

convicted of arson and murder, and both had been sentenced to death. In 

2004, Mr. Willis was granted a new trial and was later exonerated and 
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compensated. Mr. Willingham was put to death. After two years of delay, 

and another year of a contentious investigation, the TFSC hired Dr. Craig 

Beyler, who, in 2009, prepared a report entitled Analysis of Fire Investigation 

Methods and Procedures Used in the Criminal Arson Cases Against Ernest Ray 

Willis and Cameron Todd Willingham [Beyler 2009]. The report detailed 

serious deficiencies in the quality of these fire investigations. In 2011, the 

TFSC published its report entitled Willingham/Willis Investigation that listed 

17 recommendations to improve the quality of fire investigations in Texas 

[TFSC 2011]. 

The 17 recommendations were:

1. Adoption of National Standards

2. Retrospective Review of Cases

3. Enhanced Certification

4. Collaborative Training on Incendiary Indicators

5. Tools for Analyzing Ignition Sources

6. Periodic Curriculum Review

7. Involvement of SFMO in Local Investigations

8. Establishment of Peer Review Group/Multi-Disciplinary Team

9. Standards for Testimony in Arson Cases

10.Enhanced Admissibility Hearings in Arson Cases

11.Evaluating Courtroom Testimony

12.Minimum Report Standards

13.Preservation of Documentation

14.Dissemination of Information Regarding Scientific Advancements

15.Code of Conduct/Ethics

16.Training for Lawyers/Judges

17.Funding

In June 2012, Chris Connealy was appointed as State Fire Marshal by 

former Texas Insurance Commissioner Eleanor Kitzman. The SFMO is part 

of the Texas Department of Insurance (TDI). Chief Connealy immediately 

reviewed the Texas Forensic Science Commission reports, met with staff of 

the Forensic Science Commission and agreed to adopt all of the TFSC’s 

recommendations. The first task was to determine if other fire investigation 

organizations had conducted retrospective case reviews using a multidisciplinary team. After consulting with various fire investigation experts, 
125

he learned there were no operating programs that provide a model for a 

multi-disciplinary review team and a retrospective case review process. 

Creation of the Science Advisory Workgroup

After numerous consultations with various experts in the fire investigation 

profession, the SFMO developed a multi-disciplinary team of fire 

investigation experts. The term “multi-disciplinary” refers to having a 

diverse group of experts with various backgrounds and credentials (e.g., 

criminalist, engineers, attorneys, public and private fire investigators, 

pathologist, chemist) to provide advice from the professions typically 

involved with fire investigations. TDI has been very supportive during this 

entire process. The agency provided funding to increase training of SFMO 

fire investigators and additional budgeting to establish contracts with the 

majority of the panel’s experts. The SFMO decided to name its multidisciplinary panel the Science Advisory Workgroup (SAW). 

The SAW and Training

The SAW members are highly respected in their respective professions and 

represent diverse backgrounds that assist in training public and private fire 

investigators in the state. The Texas Forensic Science Commission issued 

the following recommendations related to training:

Collaborative Training on Incendiary Indicators – The Commission had 

concerns that various fire investigation myths were still being utilized by 

fire investigators as being indicative of incendiary fires such as crazing of 

glass, annealing of springs in furniture, spalling of concrete, low-level 

burning, the presence of “pour patterns” not confirmed by lab analysis, etc.

Tools for Analyzing Ignition Sources – Once the origin has been 

determined, it is critical that fire investigators identify potential ignition 

sources. The investigator must utilize the scientific method to eliminate 

potential ignition sources. 

Dissemination of Information Regarding Scientific Advancements – The fire 

investigation profession has been negatively impacted by a lack of 
126

interaction and training with fire researchers to keep up with the latest 

discoveries of science related to the profession. 

The SAW has taught numerous classes to dispel these myths through 

education and support of various reference sources. The SAW has 

provided classes on the analysis of ignition sources and additional insight 

gained through a review of past cases. The SAW aids in disseminating 

scientific advancements, utilizing the diverse backgrounds of the panel. All 

members of the SAW provide classes and feedback that allow fire 

investigators to keep up with the evolution of newly discovered science.

The improved level of training of the Texas SFMO and fellow fire 

investigators across the state is a key benefit of having the SAW. Some of 

the topics covered by SAW members during training over the past five

years include:

Residential Wiring Search and Seizure (Property &Evidence)

Fire Alarm Systems Metallurgy

CSST and Energized Gas Line Fires What to Expect Now That You are

a Fire Investigator

Thermometry Courtroom Ethics

Fire Investigations and K9s Case Organization

Pathology of Fire Deaths Fire Scene Documentation & 

Bilancia Matrix

Cyanide Inhalation Failure Analysis and Analytical 

Tools

Preparing an Expert Report Specialty Diagrams

Preparing Search Warrant Affidavit Carcinogens in Smoke

Evidence Handling and Storage Multi-meter

Water Heater Fires Arc Mapping

Lab Techniques HCN Levels

Fire Chemistry ASTM Standards & Fire 

Investigations
127

Fire Dynamics Fire Behavior

Practical Fire Modeling Expert Testimony – Surviving 

NFPA 1033

Evidence – X-rays in Fire Inv. Fourth Amendment & Fire 

Investigations

Cognitive Bias Sixth Amendment 

Scene Documentation/Aerial Vehicles Thermodynamics

Explosion Dynamics Electrical Systems

The SFMO implemented an aggressive training regimen comprised of 

hands-on training, lecture, and online education. The minimum training 

requirement that is part of the investigator’s annual performance 

evaluation is 80 hours. The average investigator gets 100 to 130 hours of 

continuing education annually. The lack of a professional development 

plan that is focused on training, certifications, and other credentials, was a 

key factor that led to the problems exposed within the SFMO in 2009.

The SFMO has made the quarterly fire investigation forums with the SAW 

available to all fire investigators in the state and forums are presented at no 

cost to participants.

The Format of the Quarterly Fire Investigation Forums

All forums are structured as three-day events. The first eight-hour day is 

devoted to various training topics and is taught by SAW panel members. 

The second day consists of a block of four hours where panel members 

make 30-60 minute presentations to update attendees on various topics to 

keep fire investigators up to date on scientific advancements and to meet 

the requirements of NFPA 1033. After lunch, there is a four-hour block of 

retrospective case reviews. The third eight-hour day is devoted to 

retrospective case reviews. 

It was quickly noted that the retrospective case reviews were very effective 

in helping the SFMO investigators become more proficient. The feedback 

from the SAW members was provided in a positive manner that created a 
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coaching environment. They pointed out the good things the investigator 

did and provided constructive criticism to identify “opportunities for 

improvement.”

Equally important, SFMO investigators were introduced to a case review 

process that none of them had ever experienced. The SFMO investigators 

deserve full credit for approaching the process with the utmost 

professionalism and a desire to become better fire investigators. 

To say this was a difficult undertaking would be an understatement. First, 

no one had ever done this before. Second, the SFMO was being watched 

very closely by the media, government officials, the fire investigation 

community, and other stakeholders to see how the agency would approach 

these changes. Finally, with the SAW and SFMO working towards a 

common goal of continuous improvement, the intensive training and the 

retrospective case review process instituted an evolutionary model that 

keeps the agency moving toward excellence. Finally, it has been noted by 

the SAW that the quality of the fire investigation reports has been 

considerably improved when comparing older cases to more current ones.

As the SFMO and SAW progressively made the fire investigation 

forums/retrospective case reviews better, in 2015, local fire investigation 

agencies were allowed to bring their cases to the panel for review. In 

February 2017, the Laredo Fire Department brought one of their fire 

investigation cases to be reviewed. This exercise went very smoothly. It is 

hoped that other local fire investigation agencies will bring their cases to 

the SAW so they can benefit from the process as much as the SFMO has 

over the past four years. Other states have been invited to participate in the 

SAW. 

Pre-Trial Case Vetting

Ideally, a pre-trial review of a fire investigation identifying erroneous 

findings before trial is far preferable to a post-conviction review. No 

prosecutor wants to convict an innocent person. The fact that findings by 

the SAW may be adverse to the State’s arson case will be revealed to the 

defense should not be a reason to abandon the review. Texas has not found 
129

a means to implement pre-trial case vetting. Maryland is attempting to 

implement a system of pre-charging reviews organized by the SFMO and 

the Fire Prevention Commission. [Maryland State Fire Prevention 

Commission 2018]

IAAI and NASFM Endorsements

After learning about what the Texas SFMO was doing in this area to 

improve fire investigations, the IAAI formed a committee to determine if 

the organization should recommend these advances to their members. In 

December 2015, the IAAI Board of Directors recommended that their 

members use a multi-disciplinary panel and conduct retrospective case 

reviews to improve fire investigations [IAAI 2015]. The Executive Board of 

the National Association of State Fire Marshals (NASFM) also passed an 

endorsement to follow a similar method as the Texas SFMO [2017]. 

● Recommendation: Require case reviews be developed and implemented, 

which can include retrospective and proactive reviews. A multi-disciplinary 

review committee can be used to assist with this process, such as the one 

implemented by Texas SFMO.

● Recommendation: Require fire investigation units to adopt a quality 

assurance system.

● Recommendation: Require all fire investigation reports to be subject to 

technical and administrative reviews. Case documentation supports the 

opinions within the report. 

● Recommendation: Develop a consensus standard for the organization and 

operation of a fire and explosion investigation unit. 

8-5 Code of Ethics

IAAI and NAFI both have a Code of Ethics. There are also state and local 

fire investigation organizations that have codes of ethics. Creating a code of 

conduct/ethics was one of the seventeen recommendations of the TFSC to 

improve fire investigations. When researching a code of ethics related to 

fire investigations, it was revealed that there are similar statements in these 

documents. Codes of ethics are typically exhortations to be an ethical 
130

example to others, challenge the individual to learn more to be a better fire 

investigator, support professional standards, avoid actions that appear 

dishonest, be non-biased, seek to protect the innocent, and hold those 

accountable for arson. It is recommended that every fire investigation 

agency have a written code of ethics to define expectations of all members 

of the agency.

Violations, Complaints, and Resolution Process Related to the Code of 

Ethics

The implementation of a Code of Ethics requires a written procedure for 

handling complaints or misconduct. Such a procedure should be detailed, 

and provide the complainant, the respondent, and the body reviewing the 

complaint with a clear set of instructions on how to proceed. This includes 

notification of the respondent, investigating the complaint procedures for 

protecting confidentiality, and potential sanctions. Different players in the 

criminal justice system have different ethical obligations. These distinctions 

should be spelled out in the Code of Ethics. 

● Recommendation: Require fire investigation units to adopt a Code of 

Ethics. 

8-6 Conclusions 

Certifications are only as good as the requirements to gain the credential. 

Governmental entities and associations that issue certifications should 

create a challenging process that stays current with the best practices of the 

profession. 

There are distinct differences between competency and proficiency testing. 

Competency testing evaluates the skills, knowledge, and abilities that are 

part of a training program. Proficiency testing evaluates the fire 

investigator’s overall performance. Both types of testing are needed to 

evaluate investigators during training and subsequent job performance. 
131

Accreditation of fire investigation units is lacking. Third-party validation of 

an organization on how it meets the performance measures within the 

accreditation documents provide a structure to comply with best practices. 

This is urgently needed to avoid the well-documented challenges identified 

by the National Academy of Sciences, media, and other sources. 

This chapter also discussed quality assurance recommendations to improve 

the fire investigation profession by establishing multi-disciplinary panels 

of experts to provide training and case reviews for organizations, to ensure 

that current science and best practices are always actively being pursued. 

The fire investigation profession must embrace these quality control 

recommendations to minimize risk exposure of poor investigations being 

sent to trial. Additionally, a proactive pre-trial case vetting process needs 

further consideration rather than just depending upon post-conviction 

reviews. Finally, the development of a code of ethics that guides the fire 

investigation unit in its daily operations, and recommendations on how to 

ensure this document is ‘lived’ by the organization was also presented. An 

adopted code of ethics by fire investigation organizations defines the 

expectations of the agency for its employees to follow in their daily 

operations. Leaders of these agencies must follow through to make sure 

these ethics are upheld.

REFERENCES

American Association for Laboratory Accreditation. (2017). 

https://www.a2la.org/accreditation/forensics

Beyler, C. (2009), Analysis of the Fire Investigation Methods and 

Procedures Used in the Criminal Arson Cases Against Ernest Ray Willis 

and Cameron Todd Willingham, Hughes Associates, Inc., for the Texas 

Forensic Science Commission. 

http://i.cdn.turner.com/cnn/2009/images/11/09/rpt.tx.forensic.willes.wi

llingham.anaylsis.final.pdf

Center for Public Safety Excellence, Commission on Fire Accreditation 

International. (2017), Accreditation Overview.
132

https://cpse.org/accreditation/

Eine Antwort. (2011). Competency vs. Proficiency Model, Learning Paths 

International, 

http://www.learningpathsinternational.com/blog/?p=5

International Association of Arson Investigators. (2015). The International 

Association of Arson Investigators Endorses the Use of multidiscipline Science 

Review Panels 

Lentini, J. (2017) Forensic Science Reform: Chapter 3-Arson. Editors Koen, W, 

and Bowers, C, Elsevier. 

https://storage.googleapis.com/production-constantcontact-v1-0-

7/507/175507/IaE9rCjE/2b4aa107107c4febbdca2e5f14656cea?fileName=20

17%20Confronting%20Inaccuracy%20In%20Fire%20InvestigationsJohn%20Lentini,%20Rachel%20Dioso-Villa.pdf

Maryland State Fire Prevention Commission (2018), Minutes from 18 

October 2018 meeting, 

https://mdsp.maryland.gov/Organization/Documents/FPC%20Minutes

%202018%2010%2018%20and%20Attachment.pdf

National Commission on Forensic Science-Views of the Commission, 

Certification of Forensic Science Practitioners (September 12, 2016). 

https://www.justice.gov/archives/ncfs/page/file/905897/download

National Commission on Forensic Science (2017), Work Products of the 

FCFS, 

https://www.justice.gov/archives/ncfs/work-products-adoptedcommission

National Board on Fire Service Professional Qualifications (2017). 

http://www.theproboard.org/

Texas Forensic Science Commission. (2011). Willingham/Willis Investigation

http://fsc.state.tx.us/documents/FINALWILLINGHAMREPORT0418113.

44pm.pdf
133

9. EDUCATION AND TRAINING IN FIRE AND

EXPLOSION INVESTIGATION

9-1 Introduction

Fire investigation is a recognized forensic science discipline that requires a 

high level of procedural knowledge as well as a working understanding of 

a variety of traditional scientific and engineering subjects.

In the United States, the educational and training requirements that 

someone should achieve before working as a fire investigator is primarily 

at the discretion of the employer. The employers of fire investigators vary 

considerably, ranging from local law enforcement or fire departments to 

federal agencies on the public side and fire protection engineering and 

investigation firms on the private side. Therefore, the employer-defined 

educational and training requirements vary widely and can range from 

virtually no training to multi-year training programs that include college 

degrees and courses and long-term apprenticeships.

The wide variation in training and education is a legacy of the rapid 

advancements in the science of fire investigation in the past several 

decades. In the past, fire investigation was a non-scientific investigative 

profession that was based upon anecdotal knowledge gained from 

experience and mentorships. Today, fire investigation is a highly technical 

field with published procedures [NFPA 921], and standardized 

qualification requirements [NFPA 1033]. Many organizations have not 

updated their training requirements to keep up with the increased 

knowledge and skills that fire investigators are expected to have.

A major challenge to educating fire investigators is that most had no 

scientific education before entering the field. This is because the majority of 

fire investigators in the United States had backgrounds as police or in the 

fire service, before transferring into the fire investigation profession. 
134

9-2 Education and Training

The lines between training and education in the fire investigation 

profession are blurred, mostly due to the lack of institutions focused solely 

on fire investigations. Many professionals may have degrees in other fields, 

but then obtain training from a variety of organizations to help round out 

their education particular to this field.

In 2012, a survey was completed that evaluated the training and education 

levels of the profession [Tinsley & Gorbett 2012]. The survey had a sample 

size of approximately 600 self-selected professional fire investigators. The 

average reported years of experience of this group was 10.5 years, with 

nearly two-thirds of the group being public fire investigators. The 

education level reported was remarkably high, with over 75% of the 

respondents holding at least an Associate’s degree and 50% having a 

Bachelor’s degree or higher. The majority of these degrees (~50%) were in 

fire science and criminal justice fields of study, with only approximately 

18% of the respondents having a degree in engineering or the physical 

sciences. The survey also showed that fire investigators participate in 

continuing professional development with the majority of the respondents 

receiving a minimum of 20 hours of continuing education per year.

Training is conducted on the state, national, and international levels. State 

agencies train to meet state requirements – typically loosely based on 

NFPA 1033. Many state agencies also certify investigators within their 

states based on attendance at this training. There are two professional 

associations that credential fire investigators at the international level, the 

International Association of Arson Investigators (IAAI) and the National 

Association of Fire Investigators (NAFI). 

9-3 Qualification Requirements for Fire Investigators: NFPA 1033

The qualification requirements for Fire Investigators are defined in NFPA 

1033: Standard for Professional Qualifications for Fire Investigator. NFPA 1033 

has been in existence since 1987 and is currently in its sixth edition. (Fire 

investigator professional standards were included in the 1977 and 1982 
135

editions of NFPA 1031, before NFPA 1033 became a standalone document 

in 1987.) NFPA 1033 is widely recognized and has been adopted by IAAI 

and NAFI as well as many public and private organizations.

NFPA 1033 is a consensus-based national standard that is published by the 

National Fire Protection Association. NFPA 1033 is updated on a 5-year 

revision cycle by a technical committee with representatives from a range 

of backgrounds. During each revision cycle, public input is requested for 

revisions to the standard. The committee may propose revisions, and 

public comments are accepted for proposed changes to the text. The 

committee considers all public input and every public comment and 

decides which changes to apply to the next edition of the standard.

The key components of the NFPA 1033 Standard are the Job Performance 

Requirements (JPRs). These JPRs define specific tasks that the investigators 

should be able to perform and describe the knowledge and skills required 

to complete each task.

Members of the fire investigation community have different views about 

which JPRs and education should be required for fire investigators. Some 

in the industry want to keep the educational requirements at the high 

school education level so that the profession can be open to as many people 

as possible. Others want to raise the educational requirements, so that fire 

investigators need a science degree to be qualified to opine on the origin 

and cause of fires. Despite these conflicting views, NFPA 1033 has evolved 

and required more qualifications with every revision. 

The minimum education required by NFPA 1033 is a high school diploma. 

Some in the profession interpret this requirement as meaning that no 

additional formal education is required regardless of what classes were 

taken in high school. However, it is generally accepted that knowledge of 

scientific and engineering concepts is necessary to produce accurate 

determinations of the origin and cause of fires. The challenge is that not all 

curricula in high school require the scientific concepts or mathematics that 

are prerequisites to learning the highly technical topics required by NFPA 

1033. 
136

● Recommendation: Fire investigators should complete college-level 

coursework in algebra, chemistry, and physics, and understand how these 

subjects relate to the behavior of fire. 

In the 2022 edition of NFPA 1033, a significant revison and re-ordering of 

the list of required knowledge was implemented at the request of the 

OSAC Subcommittee on Fire and Explosion Investigations. The list was 

moved from the administrative section in Chapter 1 to the introduction of 

JPRs in Chapter 4. The requirements now read as follows:

4.1.7 In order to successfully complete the tasks identified in the JPRs of 

sections 4.2 through 4.7, the fire investigator shall remain current in the 

subjects listed as “requisite knowledge” as they relate to fire investigations, 

which include the following.

(1) Fire science, including

a) Fire chemistry

b) Thermodynamics

c) Fire dynamics

d) Explosion dynamics

(2) Fire investigation, including

a) Fire analysis

b) Fire investigation methodology

c) Fire investigation technology

d) Evidence documentation, collection, and preservation

e) Failure analysis and analytical tools

(3) Fire scene safety, including

a) Hazard recognition, evaluation, and basic mitigation procedures

b) Hazardous materials

c) Safety regulations

(4) Building systems, including

a) Types of construction
137

b) Fire protection systems

c) Electricity and electrical systems

d) Fuel gas systems

There is an extensive new annex and entitled “Terms and Concepts”

(Annex D), which is also based on a “public input” from the OSAC 

Subcommittee. While this annex is not part of the requirements of NFPA 

1033 it is included to define the subjects and to place limits on the list of 

subjects, to describe how they relate to fire investigation, and to direct 

investigators to sources where the requisite knowledge can be obtained.

9-4 Current Sources for Fire Investigation Training and Education

Fire investigation training is available from many sources. The following is 

a summary:

Professional Training:

● National Fire Academy – The National Fire Academy offers four 

(4) classes for fire investigators and several other related courses 

for fire service personnel that are not fire investigators. R206 is a 

two-week class that provides an introduction to the many topics 

covered by NFPA 921 and NFPA 1033. R0255 provides an 

introduction to electrical systems. R0214 provides training in 

evidence collection for fire investigators. R0204 provides an 

introduction to fire dynamics and computer fire modeling.

● Many states have fire service and law enforcement training 

programs that include courses related to forensic science and fire 

investigation. 

● Professional Organization Seminars- IAAI and NAFI provide 

regional and national conferences and training opportunities 

throughout the year. 

● Employer-sponsored training – Many employers offer structured 

training programs for their fire investigators. There are also 

many ad hoc employer training events.
138

● CFITrainer.net is a free and tested online training program made 

up of many training modules in a wide variety of topics that are 

of interest to fire investigators.

Colleges and Universities:

While many colleges include a single course on fire investigation within 

their fire science programs for fire department personnel, only three (3) 

universities in the United States provide degree programs specific to Fire 

Investigation. Two Universities offer Bachelor of Science (BS) degrees and 

two offer Master of Science (MS) degrees. 

● Eastern Kentucky University offers a BS degree in Fire, Arson 

and Explosion Investigation. The degree requires a total of 120 

credit hours, including 59 credit hours in core courses and 14 

credit hours in supporting courses. Two semesters of freshman 

chemistry, college algebra, and an intensive writing course are 

required

● The University of New Haven offers a BS degree in Fire ScienceFire/Arson Investigation. The BS degree requires 123 credit 

hours, including 71 credit hours in core courses related to fire 

investigation. The degree requires one-semester courses in 

freshman chemistry, non-calculus mathematics, written 

communications, and oral communications.

● The University of New Haven offers an MS degree in Fire 

Science- Fire/Arson Investigation. The MS requires 39 credit 

hours with no specific undergraduate degree required. There are 

25 credit hours of required courses and 14 credit hours of fire 

science electives. There are no science or mathematics 

requirements.

● Oklahoma State University offers a Master of Science degree in 

Forensic Sciences with an Arson and Explosives Investigation 

Option. The MS requires 39 credit hours with no specific 

undergraduate degree required. There are 21 credit hours 

required courses and 18 credit hours of technical electives. There 

are no science or mathematics requirements.
139

The two BS degree programs provide a comprehensive education in fire 

protection and fire investigation. Both programs require non-calculus math 

courses as well as freshman chemistry and courses on building 

construction, fire protection systems, and fire science. Both programs also 

require coursework in general crime scene investigation and coursework 

specific to fire and explosion investigations. The OSAC Fire and Explosion 

Investigation Subcommittee website includes a table that describes and 

compares the courses offered at each University [OSAC Fire 2019].

A student interested in pursuing a Bachelor’s degree in fire investigations, 

but who cannot or does not want to begin their education at one of the fire 

investigations degree-granting universities may be able to take courses that 

count towards their degree plan from a local college or community college. 

A student is encouraged to evaluate the degree from the degree-granting 

institution to determine what specific general education courses are 

required (i.e., chemistry, math, English) and focus on taking the equivalent 

courses that will transfer from their local college for these general 

education courses at the degree-granting institution. Many universities 

have online databases or catalogs that list many of their classes and their 

equivalent courses at other institutions. Therefore, a student should easily 

be able to identify equivalent courses. If the local college or community 

college offers courses specific to fire protection or fire science, it is best to 

contact the degree-granting institution to determine if any of these courses 

may transfer in for credit or to delay taking any of these courses until the 

student is at the degree-granting institution. There are many fire science 

programs around the United States that offer classes in fire protection or 

fire science, but those classes may not sufficiently prepare the student for 

the upper-level classes and would therefore not be accepted for credit at 

the degree-granting institution. 

The two MS degree programs provide more focused coursework based 

upon the interests of the student. Both programs offer courses in fire 

science, risk, arson investigation, and forensic science. Each program also 

offers a variety of other courses such as fire protection systems, the 

chemistry of pyrotechnics, failure analysis, and many others. It is of note 

that neither MS program requires any specific mathematics or science 

courses. This severely limits the level of treatment of topics in these 
140

programs. The OSAC Fire and Explosion Investigation Subcommittee 

website includes a table that describes and compares the courses offered at 

each University [OSAC Fire 2019].

9-5 Path to Better Education

Additional degree programs specific to fire investigation should be 

designed and implemented at other institutions around the United States. 

A curriculum specific to fire investigation should be integrated into closely 

related fields of study to assist with those entering the field from other 

engineering and physical science degree programs. 

For fire investigators to understand the scientific aspects of the profession, 

fire investigators should be required to complete coursework from an 

accredited academic institution that includes the following topics:

Math - Topics should include a review of algebra, trigonometry, basic 

analytic geometry, exponential and logarithmic functions, coordinates and 

graphs. 

Chemistry – Topics should include the major concepts and theories 

required for an understanding of chemical phenomena, including atomic 

and molecular structure, gas laws, stoichiometry, changes of state, chemical 

bonding, solutions, and energetics in chemical reactions. Laboratory work 

should include quantitative measurements of solutions, synthesis, and 

identification of chemicals by physical and spectroscopic methods, and 

molecular modeling. 

Heat Transfer – Topics should include the three modes of heat transfer: 

conduction, convection, and radiation, one-dimensional steady and 

transient conduction, analytical and numerical methods conduction 

problems, convection heat transfer under laminar and turbulent flow 

regimes, the general characteristics of radiation heat transfer as well as the 

properties of radiating surfaces and radiation heat transfer between 

surfaces. 
141

Thermodynamics - Covers principles of classical thermodynamics by 

teaching about mass, energy, heat, work, and ideal and real 

thermodynamic processes. Topics should include first and second laws of 

thermodynamics, the ideal gas law, properties of real gases, and the 

general energy equation for closed and open systems. 

Fire Dynamics - Covers the burning behavior of materials, heat transfer in 

fires, and the fluid dynamics related to fire-driven flows. Topics include 

pre-mixed flames, diffusion flames, ignition, extinction, fire growth, and 

flame spread over surfaces, fire plumes and ceiling jets, compartment fire 

dynamics, and smoke movement. Students should solve fire-related 

algebraic problems by hand as well as solving more complicated problems 

using zone models and field models. 

Electrical Wiring Theory and Practice - Covers basic electrical theory for 

AC and DC circuits, residential and commercial building wiring, blueprint 

reading, branch-circuit installations, and service entrance installations. 

Applications and requirements taught are based on the National Electrical 

Code. Topics will include electrical circuit calculations, interpretation of 

plans, branch-circuit installations, feeder installations and calculations, 

service entrance calculations and installations.

9-6 Problems / Challenges / Proposed Solutions

There is a lack of uniformity on the amount and types of education and 

training that fire investigators are required to obtain and maintain. There is 

a lack of knowledge about NFPA 1033, and not everyone is aware that 

NFPA 1033 applies to the fire investigators in their organization. There is a 

lack of agreement in the fire investigation community about the depth of 

education that is required for the scientific subjects. People disagree about 

what is meant by “basic knowledge.” It is the Subcommittee’s hope that the 

revised NFPA 1033 will help to clear up this lack of agreement.

The work product of many fire investigators is not regularly subjected to 

challenging technical review. This can result in the perpetuation of bad 

habits and poorly documented investigations. Scientific advisory 
142

workgroups, as outlined in Chapter 7, provide opportunities for 

investigators to defend their work product and learn from past experiences 

technically. 

Most fire investigators very rarely testify in court, and the first time that 

many investigators are subjected to a challenging review of their work is 

when an investigation is going to court. This has the potential of impacting 

court outcomes. Mock Daubert motions and trials provide investigators the 

opportunity to better prepare for such hearings. 

● Recommendation: Fire investigation units should establish a formal 

process for fire investigators’ work to be subjected to challenging technical 

review. This system should include both a review of written investigation 

records and reports as well as a verbal review that simulates testimony in 

depositions and trials. Investigators should be required to submit their work 

to this process routinely. 

While NFPA 1033 requires that each investigator remain current, there are 

no requirements for fire investigation units to provide training for the fire 

investigators nor are there guidelines for what types of training should be 

provided.

● Recommendation: Fire Investigation Units should be required to establish 

a program that provides sufficient training and continuing education for fire 

investigators to meet the knowledge and Job Performance Requirements of 

NFPA 1033. 

There are many seminars available to fire investigators. The problem is that 

most of the seminars are taught at an introductory level, and there is no 

path for increasing knowledge past the introductory level. Investigators 

often attend multiple introductory seminars on a topic, but still, have no 

advanced skills in that subject area. 

There is minimal proficiency testing. The Fire Investigation professional 

organizations require ongoing training, but there is no testing to determine 

whether the investigator’s knowledge is increasing or even meeting 

minimum standards after their initial certification. 
143

● Recommendation: Continuing education should be mandatory with a 

requirement for proof that an investigator is learning up-to-date information 

and can reliably apply this information in the context of the scientific 

method. 

● Recommendation: More competency and proficiency training and testing 

focused on specific knowledge and skills should be developed for fire 

investigations. 

9-7 Conclusions:

Successfully determining the origin and cause of fires requires a wide 

breadth of practical knowledge and skills as well as useable knowledge of 

scientific subjects. The knowledge and skills that are required are defined 

in the NFPA 1033 Standard. The challenge is that most individual fire 

investigators in the United States lack the scientific knowledge required by 

NFPA 1033. 

New training and proficiency testing programs should be implemented to 

assure that fire investigators have the skills and knowledge to come to the 

correct conclusion about the causes of fires.

REFERENCES

NFPA (2022): Standard for Professional Qualifications for Fire Investigator, 

NFPA 1033, Quincy, MA. 

http://www.nfpa.org/codes-and-standards/all-codes-and-standards/listof-codes-and-standards?mode=code&code=1033

NFPA (2017): Guide for Fire and Explosion Investigations, NFPA 921, 

Quincy, MA. 

http://www.nfpa.org/codes-and-standards/all-codes-and-standards/listof-codes-and-standards?mode=code&code=921
144

OSAC Fire and Explosion Investigation Subcommittee (2019), Comparison 

of Fire and Explosion Investigation BS and MS Programs.

https://www.nist.gov/document/comparison-fire-investigationacademic-programsdec2019

Tinsley, A., and Gorbett, G. (2012). Fire Investigation Origin Determination 

Survey. Fire and Arson Investigator, Journal of the IAAI. 63 (4): Crofton, 

MD. 

https://ssem.eku.edu/sites/ssem.eku.edu/files/files/Gorbett%20-

%20FIRE%20INVESTIGATION%20ORIGIN%20DETERMINATION.pdf
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10. CONCLUSIONS

In 1979 the NFPA Committee on Fire Reporting recommended the 

establishment of a project on fire investigation [NFPA 1979]. This resulted 

in the formation of a new committee on fire investigation in 1985 [NFPA 

1985]. This committee published the first edition of NFPA 921, a Guide to 

Fire and Explosion Investigation, in 1992 [NFPA 1992]. Much progress has 

been made since the early recognition of the need to enhance the practice of 

fire and explosion investigation. Today there is much that remains to be 

done. The field of fire and explosion investigation can now be said to be in 

its adolescence, but much work is required to bring it to maturity.

In terms of the impact of NFPA 921 on fire-related litigation, progress has 

been far more rapid in civil litigation than in criminal matters. The courts 

have exercised their gatekeeper role in civil litigation far more rigorously 

than in the criminal courts. In civil litigation, the combination of Daubert

and NFPA 921 have jointly improved the quality of expert witness 

testimony in fire investigations significantly. This cannot be said in 

criminal matters. Courts have been reluctant to rigorously exercise their 

gatekeeper role in criminal matters [NAS, 2009]. Judges and lawyers need 

to be educated and trained on fire science and investigation to assure that 

only high-quality fire investigations and analyses are presented to juries. 

Both as a result of poor gatekeeping and poor funding of public fire 

investigation units, progress in the improvement of fire investigation in the 

public sector most relevant to criminal matters has been slow.

The core of NFPA 921 is the scientific method. The scientific method 

provides the framework in which the origin and cause of the fire are 

determined. Over the nine editions of NFPA 921, there has been ongoing 

progress in refining the application of the scientific method and in the 

application of fire science to fire and explosion investigation. NFPA 1033 

has taken its place in defining the qualifications of fire and explosion 

investigators.

While fire and explosion investigation certifications are in place, there is a 

need to move to the point where all fire investigators are certified. Also, 
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there is a need to improve the certification process continuously and to 

demonstrate that certification leads to improved quality of investigations. 

To date, there has been little attention given to the structure and operations 

of fire investigation units in supporting quality fire investigations. To 

initiate a focus on fire investigation unit operations, in 2016 the OSAC Fire 

and Explosion Investigation Subcommittee proposed that NFPA develop a 

standard on the Organization and Operation of Fire Investigation Units [Beyler 

2016, NFPA 2017]. In 2017 the proposal was accepted [NFPA 2017a]. In 

2018 committee members were selected, and the committee began its work 

in 2019. The proposal for the standard included requirements for an 

organization, for facilities and equipment, for compliance with safety 

procedures, for training, certification, and education, for origin and cause 

report content, for document retention, for review and approvals of 

investigation reports, and processes and management systems. It is 

anticipated that the proposed standard will be suitable to support and 

provide a path to accreditation of fire and explosion investigation units.

Developing a standard specifically for accreditation of fire investigation 

units is an important step in fulfilling the National Academy of Science 

[NAS 2009a] call for all forensic work to be carried out in accredited 

organizations. In April 2015, the National Commission on Forensic Science 

echoed this call for universal accreditation of forensic science service 

providers, including fire investigation units [NCFS 2015]. The field of fire 

and explosion investigation needs to move toward accreditation of all fire 

and explosion investigation units under the NFPA Standard when it is 

completed. All fire and explosion investigators need to be certified and 

follow standard methods while working within an accredited fire and 

explosion investigation unit. There is a need to create an environment in all 

fire and explosion investigation units of continuous improvement. The 

Science Advisory Workgroup concept, as developed in Texas, has great 

promise to enhance the quality of fire investigations. Such quality 

improvement mechanisms need to be instituted throughout the country.

In conjunction with the increased focus on fire investigation unit 

operations, there is a need to institute measures to enhance investigation 

quality. The days of individual investigators working alone are coming to 
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an end, in favor of a team approach to fire investigation. The team 

approach recognizes the complexity of fire investigations, the need for 

cooperation for safe and effective operations, and the need to reduce the 

potential for bias through the management of data collection and analysis. 

Fire and explosion investigation units need to implement information 

management practices to minimize bias and exposure to task-irrelevant 

data. Also, there is a need for fire investigation units to fully implement the 

scientific method and technical review processes to minimize potential 

bias. All stakeholders need to take responsibility for requiring complete 

and comprehensive fire and explosion investigation reports, including all 

data collected, all hypotheses formulated, details of the testing process for 

each hypothesis, and the conclusions of the investigation.

Sustained funding for fire and explosion investigation research is needed to 

move the discipline forward. The research agenda detailed in Chapter 7 

needs to be implemented. Research is needed in areas from the 

fundamentals of fire dynamics to the implementation of investigative tools. 

Particular focus is needed on the development of protocols and 

establishment of error rates for the protocols used in fire and explosion 

investigation. Research is further needed to develop methodologies that 

minimize the potential for bias. Efforts are required to assure that research 

for fire investigation is easily accessed by investigators.

It has become clear that the traditional educational requirement of only a 

high school education can no longer be accepted. The 16 knowledge areas 

which bear on fire and explosion investigation are too sophisticated for 

investigators to master the needed science and technology working simply 

from a high school education. It must be acknowledged that fire is a 

collection of complex physical and chemical processes that necessitates 

investigation by those educated in the science and practice of fire and 

explosion investigation. Today fire and explosion investigation is 

somewhat unique among the forensic sciences in requiring only a high 

school diploma to practice. There currently exist only limited opportunities 

for college-level education for fire investigations. There is a need to expand 

the number of such programs. The day when a BS in one of the physical 

sciences, engineering, or Fire and Explosion Investigation is the entry-level 

educational requirement needs to be realized in the coming years.
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While great progress has been made since the 1980s, there remains much to 

be done. This strategic vision identifies the work that is needed in the field 

of fire and explosion investigation in the coming years. Over time, these 

recommended actions are achievable with direct action and sustained 

attention. The day in which NFPA 1033, 921, and a fire investigation unit 

standard are used in an integrated manner by certified fire and explosion 

investigators with sufficient education in the discipline, working in 

accredited fire and explosion investigation units, routinely produce highquality investigations and reports under the watchful eyes of gatekeepers 

can be envisioned. It remains for us as a community to work toward 

achieving that end in the coming years.

REFERENCES

Beyler, C. (2016), Proposed Standard for the Organization and Operation of 

Fire Investigation Units, NFPA New Project Initiation Form, on behalf of 

the OSAC Fire and Explosion Investigation Subcommittee.

National Academy of Science (2009), Committee on Identifying the Needs 

of the Forensic Sciences Community; Committee on Applied and 

Theoretical Statistics, National Research Council, Strengthening Forensic 

Science in the United States: A Path Forward, p. S-8.

https://www.nap.edu/initiative/committee-on-identifying-the-needs-ofthe-forensic-sciences-community

National Academy of Science (2009a), Committee on Identifying the Needs 

of the Forensic Sciences Community; Committee on Applied and 

Theoretical Statistics, National Research Council, Strengthening Forensic 

Science in the United States: A Path Forward, p. 215.

https://www.nap.edu/initiative/committee-on-identifying-the-needs-ofthe-forensic-sciences-community

NCFS (2015), Recommendation to the Attorney General, Universal 

Accreditation.

https://www.justice.gov/archives/ncfs/file/477851/download
149

NFPA (1979), Letter from the NFPA Fire Reporting Committee to the 

NFPA Standards Council, Item 79-39 Attachment 3, March 14, 1979.

NFPA (1985), NFPA Standard Council Minutes Item 85 – 59.

NFPA (1992), Guide for Fire and Explosion Investigation, NFPA 921, National 

Fire Protection Association, Quincy MA.

https://www.nfpa.org/codes-and-standards/all-codes-andstandards/list-of-codes-and-standards/detail?code=921&year=1992

NFPA (2017), Fire Investigation Units (FIUs), Fire News, Vol. 21(10), p2 

NFPA (2017a), Standards Council Meeting Final Minutes, Meeting of 

December 2017, Item 17-12-38 https://www.nfpa.org/-

/media/Files/Codes-and-standards/standards-council/December2017/SC_Minutes_12_17.ashx?la=en