FA-127, January 1993

Basic Tools

and Resources

for Fire

Investigators:

A Handbook

Federal Emergency Management Agency

United States Fire Administration
This document was scanned from hard copy to portable document format (PDF)

and edited to 99.5% accuracy. Some formatting errors not detected during the

optical character recognition process may appear.
BASIC TOOLS AND RESOURCES

FOR

FIRE INVESTIGATORS:

A HANDBOOK

FEDERAL EMERGENCY MANAGEMENT AGENCY

UNITED STATES FIRE ADMINISTRATION

September 1992
TABLE OF CONTENTS

Chapter 1 - OVERVIEW

PURPOSE OF THIS HANDBOOK

RESEARCH METHOD

Published Request Responses

Interviews

SUMMARY OF FINDINGS

Basic Tools and Equipment

Accelerant Detection

Collection, Packaging, and Analysis of Evidence

Computers

Information Resources

ORGANIZATION OF THIS REPORT

Chapter 2 - FIELD INVESTIGATION TOOLS

HAND TOOLS AND BASIC EQUIPMENT

EVIDENCE COLLECTION EQUIPMENT

Essential Equipment

Desirable Equipment

PERSONAL AND PROTECTIVE EQUIPMENT

Personal Protective Equipment

Law Enforcement Equipment

COMMUNICATIONS EQUIPMENT

FIRE INVESTIGATION VEHICLES

Chapter 3 - ACCELERANT DETECTION

OVERVIEW

MECHANICAL AND ELECTRONIC EQUIPMENT

Catalytic Combustion Detectors

Photo-ionization Detectors

Semiconductor or Toguchi Sensor Instruments

Flame Ionization Detectors

ACCELERANT DETECTION CANINES

Training Programs

Support

Chapter 4 - COLLECTION, PACKAGING, AND ANALYSIS OF EVIDENCE

FIRE SCENE SAMPLING

Accelerant Residue Samples

Trace Evidence

Comparison Samples

EVIDENCE PACKAGING

Accelerant Residue Samples

Trace Evidence

Comparison Samples

Storage and Preservation of Evidence

FORENSIC TECHNIQUES

Accelerant Identification

Sample Preparation

Instrumental Analysis

Data Analysis

Examination of Trace Evidence

Comparison of Evidence Samples

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PHOTOGRAPHIC PROCESSING AND ANALYSIS 18

Fire Scene Photography 18

Photographic Equipment and Techniques 20

Using Fire Scene Photographs 2 1

Chapter 5 - COMPUTER SYSTEMS 23

HARDWARE 23

APPLICATION PROGRAMS 23

Word Processing 24

Database Management 24

Spreadsheets . 24

Graphics 25

Computer Communications 25

FIRE MODELING SOFTWARE 26

Chapter 6 - INFORMATION RESOURCES 27

THE FIRE INVESTIGATOR’S REFERENCE LIST. 27

JOURNALS AND PERIODICALS 27

PROCEEDINGS 29

ELECTRONIC INFORMATION SERVICES 29

Specialized Electronic Reference Sources 29

Fire Service Bulletin Boards 29

UNITED STATES FIRE ADMINISTRATION PUBLICATIONS 29

BIBLIOGRAPHY 3 1

APPENDIX A 34

APPENDIX B 37

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Chapter 1

OVERVIEW

PURPOSE OF THIS HANDBOOK

This handbook is designed to serve as a compendium of

basic information about the tools and techniques of fire

investigation. The goal here is to provide a breadth of useful

information in as concise and as accessible a package as

possible. To do this, the scope has been limited to the tools

and techniques associated with determining and verifying

the origin and cause of accidental and incendiary fires. This

is not a law enforcement procedures manual, information

about surveillance, criminal identification, interview and

interrogation procedures, insurance fraud, and procedures

related to investigating other criminal activities often associated with arson are not described here. Information about

presentation of fire-related evidence in criminal and civil

trials is only discussed in the context of how it relates to the

advantages and disadvantages of specific techniques.

RESEARCH METHOD

The information in this handbook has been assembled from

a wide array of sources, including the fire investigation and

forensic science literature, interviews with experts in fire

investigation and forensic science practitioners, and the

nationally recognized standards of practice for fire investigation and forensic science. Members of both professions

from across the country, and in one case another country -

Australia - have lent their considerable experience and

expertise to this project by responding to published requests

for information and participating in interviews about what

they do and how they do it.

Published Request Responses

The published requests for information were circulated to all

of the major fire service, fire investigation, code enforcement, and fire protection publications asking investigators

to respond to the following questions:

What basic tools are issued to all your

investigators? (Please provide lists)

What equipment not currently available to you do you most need?? (Please

identify)

Do you currently use canines in fire

investigation? Are they certified? Have

their findings held up in court?

What type of gas chromatograph do you

use? How has it performed?

Where do you send your evidence - to

your own lab, the police department

lab, a state lab or a private lab?

Useful responses were received from 29 fire investigation

units. These agencies, shown on page 2, represented all

types of fire investigation units, career and volunteer, from

a diverse range of communities large and small, urban,

suburban, and rural. Agencies from different levels of

government responded as well, including state fire marshal’s

offices, county fire investigation units, and local fire investigators. Two encouraging results were apparent from the

nature and diversity of the responses. First, that despite their

differences, all of these jurisdictions had many things in

common about the way they conducted fire investigations

and what they used to do this. The other was just as important

- that despite the similarities, there was no single way to do

everything.

These responses provided valuable insight into the administrative environment in the fire investigation field.

Interviews

To corroborate and further expand on the findings of the

publication responses, a series of interviews with local,

state, and federal fire investigators and laboratory personnel

from across the nation was conducted. The agencies involved are shown on page 2. These interviews provided

additional insight and valuable background information

about the use of technology, disputes about techniques, and

the advantages and disadvantages of various methods or

procedures.

As a result of these responses, this handbook tries to do three

things:

Explain what is out there and how it is used;

Explain how much things cost and what

advantages, disadvantages, costs, and benefits are associated with the tools and techniques described;

And, explain what constitutes a good

basic or minimum complement of tools,

equipment, and technical capability.

1
Fire Investigation Units

Responding to Request for Information

Allentown Fire Department, PA

Atlantic County Prosecutor’s Office, NJ

California State Fire Marshal’s Office, CA

Chino Valley Fire Department; CA

Cincinnati Division of Fire, OH

Clark County Fire Department, NV

Colerain Township Fire Department, OH’

District Six Volunteer Fire Dept., Baton Rouge, LA

Gainesville Fire/Rescue Department, FL

Hall County Public Safety Department, GA

Hartford Fire Department, CT

Kent Fire Department, WA

Lewis County Fire Investigation Unit, NY

Maryland State Fire Marshal’s Office, MD

Metropolitan Fire Brigades Board, Melbourne, Australia

Mokena Fire Protection District, IL

Moss Township Fire Department, MS

Orange County Fire Department, CA

Palm Bay Fire Department, CA

Piqua Fire Department, OH

Riley Township-Pandora Volunteer Fire Dept., OH

Rogers Fire Department, AR

San Mateo Arson Task Force, CA

Sellersburg Fire Department, IN

South Kitsap Fire Department, WA

Ventura County Fire Protection District, CA

Vineland Fire Department, CT

Windsor Fire Department, CT

Wyoming Dept. of Fire Prevention and Electrical Safety, WY

Agencies Interviewed

Arkansas Department of State Police, Fire Marshal Section

U. S. Department of the Treasury, Bureau of

Alcohol, Tobacco, and Firearms

Connecticut State Police, Canine Section

Eastern Kentucky University, Department of Loss

Prevention and Safety

Florida Division of State Fire Marshal

Insurance Committee for Arson Control

lnternational Association of Arson Investigation, Forensic

Science and Training and Education Committees

Minnesota State Fire Marshal Division

Nebraska State Fire Marshal’s Office

Oklahoma City Fire Department, OK

Pennsylvania State Police, Fire Marshal Division

Portland Fire Bureau, OR

Wyoming Dept. of Fire Prevention and Electrical Safety

SUMMARY OF FINDINGS:

Basic Tools and Equipment

Fire investigators are using a wide variety ‘of tools and

equipment in their work. Many of these are commonplace,

others quite unique and sophisticated. Many departments

have either acquired or desire electronic equipment like

video cameras, cellular telephones, facsimile machines, and

personal computers. A decided trend throughout the publicsafety field which was not strongly demonstrated by the

publication responses but reinforced during interviews, was

the need for personal protective equipment for fire investigators. Several fire investigation professionals pointed out

the riced for respiratory protective equipment, and one noted

the need for latex gloves for preventing contact with bloodborne pathogens. Yet another office discussed the need for

Hepatitis B vaccinations for its employees. Many agencies

employed sworn law enforcement officers who were issued

firearms, ammunition, handcuffs, and ballistic vests.

Accelerant Detection

A traditional law enforcement approach - the use of

canines for detection purposes - is gaining popularity for

accelerant residue detection. Hand-held electronic “sniffers” remain popular as well. Some agencies use both

techniques in tandem to increase their sampling confidence.

Both techniques have their proponents. Both have become

well-established means of identifying accelerant residue

samples for collection and analysis. Likewise, both have

been accepted in court. So far, no one is reporting any

problems with canine evidence in court proceedings. However, many forensic science professionals caution that if

rigorous training and certification standards are not established and maintained, this excellent record may be in

jeopardy.

Collection; Packaging, and Analysis of Evidence

Much of the early attention here focused on laboratory

techniques, but as work progressed it became evident that

procedures for collecting, packaging, and storing evidence

were equally if not more important. Analysts interviewed

during the development of this manual and published articles in the literature emphasized that evidence which is not

collected or which is collected or handled improperly will

severely compromise any investigation. Since no clear

guidelines exist on what evidence or how many samples to

collect, interest shifted to determining if guidelines were

discernable from the current practices in the field. Advances

in packaging technologies have introduced a few innovations, such as KapakTM bags which are resistant to vapor

leakage, but the best evidence containers for accelerant

residue samples remain clean metal paint cans with friction

lids. Beyond collection and packaging, the nature of the fire

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scenario and, the types of evidence submitted to the laboratory determine how it is processed by the forensic science

technicians. The effectiveness of, an analysis is heavily

influenced by communication between the field investigator

and the laboratory analyst.

Computers

The use of computers in the fire service has been growing as

elsewhere in business and government. Federal efforts to

develop useful computer-aided tools for fire investigators

began in the early 1980s with the United States Fire

Administration’s development of the Arson Information

Management System (AIMS). Literature research and

interviews revealed that a large number of commercial

products exist which, follow the AIMS lead. Also, a wide

variety of application programs exist for word processing,

database management, graphics, communications, and numerical analysis. As these programs have become more

“user-friendly” they have become more popular among fire

investigators. Investigators can use most of the popular

commercial programs for writing reports, preparing fire

scene diagrams, maintaining investigation records, analyzing financial information and fire statistics, and communicating with other fire protection and law enforcement professionals via electronic information services. The horizon

for use of computers in the fire service continues expanding

with the introduction of increasingly sophisticated computer

fire models for analyzing complex fire protection problems.

Programs like the National institute for Standards and

Technology, Building and Fire Research Laboratory’s (NlST/

BFRL) HAZARD I model are designed to be easier learn

and use. These programs offer fire investigators a set of tools

for understanding and documenting what happened in fires

they investigate.

Information Resources

All complex, fields of knowledge are under continuous

revision and interpretation. Fire investigation and fire

science are certainly no exceptions. Keeping well-informed

and current is a constant challenge. Fortunately, fire investigators have access to a wide array of information resources,

including periodicals, books and texts, codes and standards,

on-line information services, and conference proceedings.

The federal government maintains: a large number of reference sources for fire investigators, including the Fire and

Arson Investigators’ Field Index Directory, Arson Resource

Directory, Establishing an Arson Strike Force, and A View

of Management in Fire Investigation Units.

ORGANIZATION OF THIS REPORT

The authors chose to organize this handbook much the same

way a good investigator conducts an origin and cause

inquiry. The fire investigator works from the least burned

or damaged area to the most heavily damaged area in a

systematic fashion, collects information and evidence, processes the information, analyzes the results and presents his

or her case to a prosecutor and/or court. This handbook

works from the hardware, tools, and equipment used at the

fire scene to the scientific and technical information and

analysis necessary to resolve a complex case.

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Chapter 2

FIELD INVESTIGATION TOOLS

The most important fire investigation field tools are keen

observational skills, innate curiosity, and an interest in

determining the truth. This section details the hardware

required to put the basic tools of intellect, observation, and

perseverance to work in a difficult and challenging environment - the fire scene. The utility of all of these tools and

equipment can be expanded by proper training and use.

This discussion includes accidental and incendiary alike.

Some of the tools discussed are considered useful in determining the origin or cause of either incendiary or accidental

fires, most are useful in investigating both types of fires.

HAND TOOLS AND BASIC EQUIPMENT

Fire investigators must perform many of the tasks associated

with overhaul in the process of identifying and eliminating

potential ignition sources, collecting evidence, and determining the mechanisms of fire behavior and fire spread.

Some simple hand tools and other equipment should be

carried by or be available to fire investigators to perform

tasks such as disassembling equipment, opening packages,

removing interior finish and trim, and obtaining evidence

samples. The following sections detail the equipment

investigators say they use to perform many routine fire

investigation tasks. These items include tools for cutting,

drilling, prying, loosening, and measuring. A complete list

of these tools appears in Appendix A.

EVIDENCE COLLECTION EQUIPMENT

Evidence collection and preservation is one of the most

important tasks associated with fire investigation. Everything needed to confirm the cause, origin, or contributing

factors associated with a particular fire must be collected and

catalogued. In the case of incendiary and suspicious fires,

evidence about suspects and people associated with the

premises or the fire scene must be collected and preserved

as well.

Essential Equipment

Key tools associated with these tasks include equipment for

photographing, collecting, marking, and preserving fire

scene debris samples, materials for documenting and diagramming the overall condition of the scene, and tools for

collecting the statements and accounts of witnesses. A list

of basic evidence collection equipment appears in Appendix

A. Many of the items on that list are quite costly. Some

departments with limited budgets will find it necessary to

limit their equipment to the bare essentials. Some of the

basic evidence collection equipment may include a simple

35-mm automatic camera, a small assortment of evidence

containers, a measuring tape or rule, and drawing and

writing supplies.

Desirable Equipment

Many agencies have acquired video camcorders, videocassette recorders, and videotape editing machines or placed

them high on their “wish lists.” Video and advanced

telecommunications are two of the fastest growing capabilities of most fire investigation units. Although sophisticated

high-resolution video camcorders capable of operating in

low-light-level conditions costs approximately $2,000, a

reasonable videotape camcorder and playback unit can be

obtained for less than $1,200. Videotape capability has

become so popular so quickly because it provides the

investigator with a tool for capturing action and documenting the fire scene while maintaining spatial and temporal

perspective. Moreover, when the fire investigator can arrive

at the scene before the fire is extinguished, videotape is afar

superior method of capturing live action fire sequences for

reconstructing the fire scenario later.

The use of videotape as a law enforcement and investigation

tool has become so commonplace that many law enforcement agencies have begun mounting videotape cameras in

their vehicles to record routine traffic stops. Following suit,

some fire departments are considering installing video

camcorders in fire apparatus to record fire operations.

Likewise, many fire investigation units use video camcorders to routinely record the crowds assembled at fire scenes

to identify possible arson suspects. All of these applications

are significantly enhanced by editing capability. Raw

videotape can be edited and captioned to reinforce key

points for training purposes or to highlight key points when

used for presentation at trial.

PERSONAL AND PROTECTIVE

EQUIPMENT

Most fire investigators assigned to fire service or law

enforcement units will need some basic equipment for their

personal use and protection. Items like badges, ID cards,

business cards, and uniforms help identify them to the

public, which can cut two ways: it can help protect them or

identify them as a target. Items like flashlights and clipboards are basic tools for most investigators as well. Fire

scenes are inherently dangerous places to work; therefore,

protective equipment should be provided to minimize the

risk of personal injury. A list of personal and protective

equipment appears in Appendix A.

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Personal Protective Equipment

In recent years, increased awareness of the hazards to

firefighters have produced significant improvements in

personal protective equipment. However, the hazards to fire

investigators are often given inadequate consideration. Just

because the fire is out does not mean the hazard has passed.

Toxic combustion products like carbon monoxide, carbon

dioxide, cyanides, sulphur dioxide, hydrogen sulfide, acrolein, nitrogen oxides, and other substances exposed by the

fire such as asbestos are just a few of the toxic inhalation

hazards present on the fireground after a fire is extinguished.

Fire weakened and water-logged structures present the

continuing danger of collapse; and, sharp objects and deformed materials may present trip, fall, or abrasion hazards.

In short, the fireground only becomes marginally less hazardous after the fire is out, and fire investigators must

recognize and protect themselves from many of the same

hazards as firefighters. These include the hazards of acute

exposures which may incapacitate an investigator immediately and those which produce chronic or long-term health

effects which produce gradual debilitation.

Many investigation units now issue their investigators halfmask respirators and air monitoring equipment to guard

against fireground inhalation hazards. The most popular

filters for use with these respirators are designed to filter out

volatile organic chemicals, acid vapors, and particulate. Air

monitoring equipment is used to detect and alarm upon the

presence of diminished oxygen concentration or the presence or elevated carbon monoxide levels.

Coveralls, steel toe, steel shank shoes or boots, hardhats or

helmets, firefighter turnout clothing, gloves, and goggles

complete the fire investigator’s protective ensemble. These

items prevent injuries from abrasion, impact, and puncture.

A list of protective equipment appears in Appendix A.

Law Enforcement Equipment

Some fire investigators have dual authority to investigate

fires and make criminal arrests. Different duties come with

the added authority of sworn law enforcement officers.

These factors also influence how the fire investigators, the

public, and potential suspects may interact. Most law

enforcement officers not only possess the right to bear

firearms, but a duty to carry these weapons on and off-duty

as well. The risks associated with carrying and using

firearms bear special consideration for fire investigators.

The issuance and use of ballistic vests should be seriously

considered anytime fire investigators will USC or carry

firearms, as well as when they expect them to be used against

them. To further minimize the risks of bodily injury to them

or members of the public, most law enforcement agencies

require suspects to be restrained when taken into custody. As

such, handcuffs or other restraint devices should be issued

when the fire investigator’s authority and duties include

arrest powers.

COMMUNICATIONS EQUIPMENT

The acquisition of communications equipment has become

one of the top priorities of many fire investigation agencies.

The reasons is clear: access to the right communications

equipment saves a fire investigator time and enhances his or

her ability to do a good job. With the costs dropping rapidly,

most of these tools are now within easy reach of most public

agencies. However, while the costs of acquiring tools like

cellular telephones or facsimile machines may be relatively

low, the cost of using and maintaining such services is

usually higher than standard telephone service. Agencies

should become familiar with the costs of operating cellular

telephones, pagers, and facsimile machines to prevent unwelcome surprises.

FIRE INVESTIGATION VEHICLES

Many agencies have found it desirable to have a dedicated

vehicle for transporting the wide array of tools and equipment they require to fire Scenes. Often these vehicles also

serve as command posts. Like other fire service or law

enforcement vehicles, these “arson vans” are often highly

specialized. Usually, a fire investigation field unit consists

of a van or truck with an enclosed cargo body. Most are

equipped with emergency response equipment, public address systems; and radios. Field units of this type permit fire

investigators to bring a wider variety of tools and equipment

to the scene than would be possible with a staff car. Some

of these items include digging tools, salvage tools, and scene

security supplies. Some units are equipped with cellular

telephones, cellular facsimile machines, portable computers, remote surveillance equipment, and forensic analysis

equipment. The configuration of a local fire investigation

field unit should be tailored to the jurisdiction’s particular

needs and budget. State motor vehicle laws dictate the types

of warning equipment required if the unit will be used to

respond to emergencies.

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Chapter 3

ACCELERANT DETECTION

One of the principal techniques for evaluating whether a fire

is incendiary is to test for the presence of flammable or

combustible liquid accelerants. This section presents the

most widely used techniques for detecting the presence (not

the concentration) of flammable or combustible liquid accelerants in fire debris. Regardless of the investigative

technique employed - analytic equipment, accelerant detection canines, or the investigator’s senses of sight, touch,

and smell - its reliability is dependent upon experience and

judgement.

OVERVIEW

Eight types of field tests or instruments are recognized as

valid for detecting the presence of flammable liquid vapors

at fire scenes. However, only five of these methods have

proven practical enough to become widely used on the

fireground.

Many fire investigation agencies use mechanical or electrical devices for detecting the presence of flammable liquid

accelerant vapors. Although four types of these devices,

sometimes referred to as “sniffers,” have proven reliable and

widely popular, each has distinctive reliability drawbacks.

“Portable” versions of gas chromatographs and spectrophotometers have been tried in the field, but have proven to

unstable to be reliable.

Chemical indicators which change color in the presence of

specific hydrocarbon compounds were tried in the field but

found impractical. Unfortunately, this method is often too

inaccurate or unspecific for fire investigation needs and is no

longer widely used.

Human olfactory testing, is the oldest and most widely

practiced accelerant detection technique. It involves the

investigator smelling fire debris for the characteristic odor

of a flammable solvent. The major drawback of this method

is that the human sense of smell becomes fatigued after

prolonged exposure to certain chemicals. However, in

recent years the introduction of accelerant detection canines

has vastly improved the reliability and performance of

olfactory analysis at fire scenes. Trained dog and handler

teams have demonstrated dramatic improvements in consistency, reliability, and performance in accelerant detection as

verified by forensic analysis. This section examines the use

of mechanical or electrical detection instruments and the use

of accelerant detection canines. Although one form of

detection may appear preferable to another, no detection

method is 100% reliable or accurate. Many agencies,

therefore, prefer to use more than one field detection technique to improve their sampling “hit” rates.

MECHANICAL AND ELECTRONIC

EQUIPMENT

Mechanical or electrical devices for detecting the presence

of accelerant vapors fall into four major categories: catalytic

combustion detectors, photo-ionization detectors, Toguchi

sensor or semiconductor-based instruments, and flame ionization detectors. Detectors based on the catalytic combustion principal have traditionally been the most common and

widely used instruments for detecting the presence of accelerants, but both photo-ionization and semiconductor-based

instruments have become increasingly popular because of

their improved sensitivity and selectivity. Flame ionization

detectors are the least common of these field instruments.

Catalytic Combustion Detectors

A catalytic combustion detector consists of three basic

components: a pump or other means of drawing a sample of

vapor/air mixture into the instrument; a chamber containing

a platinum wire coil which is part of a circuit known as a

“Wheatstone Bridge”; and, a gauge for indicating thechange

in the resistance of the coil. These detectors operate on the

simple electro-mechanical principal that heat and electrical

resistance are related. When a sample of accelerant contaminated vapor/air mixture is drawn into the chamber, the

heat from the coil quickly oxidizes it, causing a temperature

rise. This increase in temperature increases the resistance of

the coil, which is registered on the instrument’s gauge. The

specific heat of combustion for a given gas or vapor is

peculiar to its molecular weight and concentration.

Most catalytic combustion detectors are calibrated to minimize interference from trace hydrocarbons normally present

in background air samples. Gauge markings usually correspond to concentrations of a known flammable gas or vapor

concentration, very often methane. Some of the more

elaborate devices produce audible warnings when the detected concentration excecds certain proportions of the

‘calibration gas’s lower explosive limit. Since these devices

are usually calibrated against a single known flammable gas

or ‘vapor as a standard, their reliability at predicting the

concentration, of other materials or mixtures of material

vapors of varying molecular weights is questionable. Nonetheless, most manufacturers supply conversion charts for

translating instrument readings for the calibration standard

into equivalent concentrations of other compounds.

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Figure 3.1

Accelerant Detection Techniques

Test Method Detection

Sensitivity Range

Comment

Chemical color test 1 - 5 parts per 1,000 Least specific and sensitive

detection or test method.

Catalytic combustion 1 ppm Noise from pyrolysis

products may interfere with

results.

Photo-ionization detector 0.1 - 1 ppm Good sensitivity and

selectivity. Moisture and

condensation do not affect

sensitivity or selectivity,

but may produce inaccurate

output.

Semiconductor or Toguchi

sensor-based instruments

1 - 5 ppm Dual sensor devices have

good sensitivity and

selectivity, but may take

more time to setup.

Hydrocarbon residue

accumulation may diminish

sensitivity.

Flame ionization detector 1 - 5 ppm May yield false “positive”

results.

“Portable” gas

chromatograph

1 - 5 ppm Very expensive, not totally

portable, requires calibration after setup, lengthy

analytic procedure.

“Portable” infared

spectrophotometry

1 - 5 ppm Needs pure sample.

Impractical for field use.

Olfactory test 1 ppb Human olfactory sense can

suffer from fatigue. Canine

sensitivity and reliability

dramatically superior.

Source: Lee, H. C. and Messina, D. A., Evaluation of Arson Canine Testing Program, Meriden, CT:

Connecticut State Police, Forensic Science Laboratory.

7
The simplicity of catalytic combustion detectors, case of

operation, and widespread use in other emergency services

applications such as detecting natural gas or liquified petroleum gas leaks have made them the most popular and widely

used type of accelerant detection instrument. Many of these

instruments also now feature solid state electronics, digital

readouts, print recorders, and oxygen sensors.

Photo-ionization Detectors

Photo-ionization detectors use a high frequency light source

in the far ultraviolet range to produce ionize contaminants

in air samples entering the detector. When hydrocarbon

samples are ionized, the free electrons are attracted to a

cathode. The resulting change in current is amplified and

registered by a device like a meter or strip chart recorder.

These devices are usually quite sensitive and exhibit good

selectivity for hydrocarbon vapors. Photo-ionization detectors are considered to be up to ten times more sensitive than

flame-ionization detectors, and are much more stable. The

stability of the photo-ionization detector is a product of the

energy source and power supply. Unlike the flame-ionization detector’s hydrogen fueled flame, the battery powered

ultraviolet light source produces a consistent and reliable

energy source.

Moisture and temperature extremes may affect instrument

readings. The presence of hydrocarbon pyrolysis products

in the fire debris matrix may yield false positive readings,

but perhaps no more so than other devices. An experienced

operator can readily interpret the readings provided by the

instrument by considering the sources analyzed.

These devices are small, very portable, and easy to purge,

permitting rapid sampling of suspect areas. A good photoionization detector instrument costs approximately $4500.

Semiconductor or Toguchi Sensor Instruments

Instruments based on the Toguchi sensor employ a semiconductor chip to detect the presence of hydrocarbons vapors.

Elevated hydrocarbon concentrations in air infiltrate the

chip’s crystalline structure, changing its conductive properties. These are registered and amplified to produce an analog

reading on a meter. This simple design coupled with a

duplicate sensor permits background sources to be eliminated through calibration or comparison.

One of the leading manufacturers of semiconductor based

instruments for accelerant detection produces a device

which employs dual sensor technology and multiple probes

to permit the operator to zero-out background sources. This

facilitates easy identification of pattern boundaries where

liquid accelerants may have been poured to create trailers or

fuses. Some devices also offer interchangeable sensors to

permit variable selectivity for different applications.

Since hydrocarbonsarc permitted to enter the semiconductor’s

structure, they must burn-off before the device can be

cleared to screen a new sample. Although this takes very

little time in most cases, it can slow down even an experienced investigator. Moreover, some users complain that

these devices become contaminated over time, making it

increasingly difficult to eliminate background interference.

Another serious limitation is that exposure to silicon vapors

from certain sources such as brake fluid and some lubricating oils will destroy the sensor element.

A semiconductor-based instrument costs approximately

$1200.

Flame Ionization Detectors

Flame ionization detectors mix the sample vapor/air mixture

with gaseous hydrogen and burn the mixture. The high

temperature flame produced by this combustion causes the

molecules in the mixture to ionize; that is, break down into

electrically charged chemical species. This causes the gas

mixture to become electrically conductive. The degree of

ionization, hence the degree of conductivity of the gas

mixture, is measured using an electrometer to produce a

reading indicating the presence of accelerants.

This technique is capable of detecting much smaller quantities of accelerant than catalytic combustion detectors and

reporting them much more accurately. However, the sensitivity of the device often works against its reliability by

producing false positive readings in the presence of pyrolysis products of certain materials like plastics and chemically

treated wood. Another significant drawback is the need to

carry a portable hydrogen fuel supply.

ACCELERANT DETECTION CANINES

The first accelerant detection canine program was developed in 1986 through a joint program of the Bureau of

Alcohol, Tobacco, and Firearms, Connecticut State Police,

Connecticut Bureau of State Fire Marshal, and New Haven

(CT) State’s Attorney’s Office. Since that time, dozens of

agencies nationwide have followed suit. Still, even ardent

advocates of accelerant detection canine programs stress

that the use of the dogs is just another weapon in the fire

investigator’s arsenal. They emphasize that training and

support are the keys to successful use of this technique.

Training Programs

Many agencies and organizations have responded to meet

the growing demand for accelerant detection canines. However, like any service, some programs and trainers are better

and more credible than others. Aside from the technical

differences in the training methods employed by each, the

8
truest test of the credibility and performance of a canine

training program is the results its dog/handler teams produce. The field performance of any program’s graduates

should be a significant consideration when evaluating and

selecting a trainer for a new accelerant detection program.

A key measure of their success is the percent of samples

taken that prove accurate. The best programs claim a 97%

“hit” rate for samples identified and submitted by accelerant

canine teams for forensic analysis. Such high accuracy rates

are obtained by rigorous training and recertification and a

continual process of verification by forensic analysis.

The Connecticut State Police Canine Unit and the Maine

State Police are two of the principal governmental agencies

involved in training accelerant detection canines for law

enforcement use. Both agencies offer training programs

throughout the year for very reasonable fees. Each has

demonstrated consistent success and proven results with its

graduate dog/handler teams. These agencies may be contacted at the following addresses and phone numbers:

Canine Section

Bureau of State Fire Marshal

294 Colony Street

Mcriden, Connecticut 06540

(203) 236-6046

Maine Criminal Justice Academy

93 Silver Street

Waterville, Maine 04901

(207) 873-2651 or (207) 873-4691

Support

Effective use of accelerant detection canines is a team effort.

Their success is founded in cooperation between law enforcement, fire investigation, forensic science, and criminal

justice agencies. Agencies using accelerant detection canines stress that the dogs are just another tool for combatting

arson. As a tool, their effectiveness is limited by the training

and abilities of the trainer, handler, origin and cause investigator, law enforcement agency, forensic laboratory, and

prosecutor responsible for investigating and prosecuting the

case. The following general guidelines should help identify

the types of support required to establish and maintain an

effective accelerant detection canine program:

Dogs and handlers should be trained as a

team by competent professional canine trainers with a proven track record training law

enforcement working dogs, preferably for

specific use as accelerant detection canines.

Accurate and contemporaneous records should

be maintained of all dog and handler training,

fire scene experience, and laboratory results of

samples submitted for fire scenes and

recertification or validation purposes.

A rigorous daily training and work program

should be established and followed to maintain

and document the proficiency of the canine and

handler.

Accelerant detection canines should be used

primarily to identify locations for collecting

flammable or combustible liquid accelerant

samples. Every location where an animal alerts

to the presence of an accelerant should be

sampled, and all samples should be submitted to

a forensic laboratory for analysis and

confirmation.

Canines should be worked at every possible

opportunity, accidental fire scenes included, to

build experience and confidence. When canines

work “negative” scenes, they should be

reinforced afterwards with a “positive” training

hit. This ensures that the dog is ready and

willing to work every fire scene opportunity.

Accelerant detection canine team evidence and

testimony are credible and persuasive, but should

never be relied on too heavily to build a case for

prosecution. Canine teams should avoid letting

their confidence in the dog’s abilities persuade

them to prosecute otherwise weak cases.

Just because a dog does not alert at a scene does

not mean the fire was not incendiary. Dogs are

not perfect and neither are fire investigators.

Every time a dog is used at a fire scene the

investigator should have a clear understanding

of what he or she expects to find or confirm.

Negative and positive results alike must be

evaluated carefully to determine what they mean

to the fire investigation.

Successful use of this technique requires that each team

member - canine handler, fire investigator, law enforcement professional, forensic scientist, and prosecutor - be

knowledgeable about how the dog’s use impacts their area

of expertise and how it relates to their testimony at trial.

9
Chapter 4

COLLECTION, PACKAGING, AND ANALYSIS OF EVIDENCE

The successful presentation of fire scene evidence of incendiarism is often dependent upon the ability to document and

verify the presence of accelerant residue in debris samples.

Likewise, laboratory analysis often yields significant clues

about the performance of fire protection features or factors

contributing to fire growth and spread. A successful fire

investigation program uses the scientific method at the fire

scene and behind the scene - in the laboratory. This section

discusses the procedures and equipment used in the forensic

science community to conduct laboratory analysis of fire

scene debris samples and photographs. The techniques

discussed here will have applications to accidental as well as

incendiary fires.

Only the fire investigator can determine what evidence

needs to be collected to document a particular fire,. Techniques used to collect, package, and store evidence for

forensic analysis are dictated by the types of evidence and

analytic techniques involved. Three types of analysis are

commonly performed by forensic laboratories: accelerant

identification, comparison of evidence samples, and trace

evidence examination: Each of these involves specialized

analytic techniques. In addition to these techniques, photographic evidence is also a valuable tool for understanding

and documenting the fire scene.

FIRE SCENE SAMPLING

Identifying what to collect and where to collect it is the most

important decision an investigator must make with regard to

forensic analysis of evidence. Collecting insufficient evidence or sampling in the wrong location can severely cripple

the development of a complete fire origin and cause scenario. Moreover, if evidence is not collected during the

initial investigation, it may be destroyed, diluted, or altered

to the extent that it becomes unavailable, inconclusive, or

inadmissible in court.

Accelerant Residue Samples

Considerable discussion has taken place in the fire investigation literature concerning how many accelerant residue

samples should be collected at any given fire scene. Most

laboratories collect and analyze statistics about the work

they perform. One laboratory has suggested that a specific

number of samples is adequate for achieving positive results. Collecting more samples that the specified number,

they argue; will produce only negligible results. However,

the ratio of positive samples to negative samples submitted

by any given fire investigator may prove little or nothing

about the investigator’s sampling techniques. In fact, good

investigation technique should include submitting samples

to confirm and refute the presence of accelerant residue. In

practice, only the experienced fire investigator can determine how many samples will be required to adequately

document a particular fire. Statistical evidence is important

in ensuring quality control, but it should be interpreted with

caution..

The presence of flammable or combustible liquid residue,

particularly where such evidence would not normally be

expected, may be a good indicator of incendiarism. However, many other cases involve the collection and analysis of

such debris samples to rule-out the presence of accelerants

or to identify possible flammable or combustible liquid

residues from sources other than accelerants.

The following general principles extracted from the fire

investigation literature should apply to the selection of

debris samples:

The collection of debris samples for

identification of accelerant residue should

begin as, soon as possible after fire control

efforts have been completed. ‘Fire effects,

evaporation, and dilution or dispersion by fire

streams all diminish the chances of collecting a

positive sample where one should be present.

The best place to sample for accelerants is at the

periphery of so-called pour patterns. This is

often evidenced by a distinct interface between

the most heavily damaged area and the less

damaged areas.

Absorbent materials like carpet and padding,

soft woods, fabric from clothes, linens, or drapes,

paper,, and soil make better samples than nonabsorbent, materials like glass, tile, and

concrete.* However, some types of concrete

actually, make good samples, especially when

the sample is particularly porous and collected

before the potential accelerant sample can be

diluted, dispersed, or evaporated.

Clean, dry absorbent cotton, sanitary napkins,

or clean, dry cotton baby diapers make good

absorbent materials for collecting flammable or

combustible liquid residues on non-porous materials. Commercially available absorbent pads,

such as those made of polypropylene, are unsuitable for, this purpose because they often contain

10
background contamination: These products are

commonly used in hazardous materials cleanup and are designed specifically for that purpose, not evidence collection.

Calcium carbonate or activated charcoal may be

used to adsorb accelerant residues from concrete. A thin layer of one of these materials

spread evenly over the surface where a residue

is suspected can collect a significant quantity of

liquid. The material and a small sample of the

non-porous surface should be collected and

submitted for analysis.3

The container in which the accelerant was transported to or used at the scene is the best source

of an accelerant residue sample.4 Even fire

damaged containers often contain sufficient flammable or combustible liquid residue to permit

analysis. Moreover, container labels and markings often provide additional valuable clues.

Trace Evidence

Trace evidence includes a very wide array of materials or

clues other than accelerant samples which may indicate the

identity of a suspect(s), the motive(s), or the origin and cause

of the fire. Items under this heading include:

Serological samples, e.g., blood, hair, and skin,

from which blood type or a DNA “fingerprint”

can be identified. This type of evidence is often

indispensable in identifying or eliminating possible arson suspects. As the scientific methods

associated with DNA fingerprinting become

more widely accepted and the procedure more

common, this may also become a useful way of

identifying fire victims.

Questioned documents, e.g., financial records,

checks, letters, business papers, insurance

policies or certificates, securities, and property

records or titles. When, why, and how a document was prepared as well as what information

it contains may provide valuable clues about

why a fire happened and who may be responsible for setting it if arson is suspected.

Latent fingerprints. Fingerprints can be a valuable means of identifying suspects in arson

cases, as well as establishing positive identification of fire victims. Latent fingerprints may

often be recovered from other forms of trace

evidence, such as Molotov cocktails, accelerant

containers, and failed incendiary devices. Even

small fragments of these containers or devices

may contain sufficient information to permit a

positive identification.

Device remnants, e.g., pipe parts or fragments,

machine or appliance parts, wire or metal

samples, container fragments, chemical incendiary residues, and other materials. Many forensic science laboratories maintain extensive exemplar files of materials used in the manufacture of incendiary and explosive devices. Even

small fragments can often be identified using

undamaged original pieces from these files.

Many other articles are extensively catalogued

and can be used to identify remnants of virtually

any device or component. Appliance parts can

often be identified using repair, guides and maintenance manuals. Wiring and metal, parts often

provide valuable clues about localized heating

or temperatures at different points in the fire if

examined closely by a trained technician. Chemical incendiaries may be manufactured from a

wide variety of common consumer products

such as swimming pool disinfectant, hair gel,

soap powder, brake fluid, and road flares. Often

residues from failed incendiaries provide valuable clues about the ignition scenario.

Toolmarks. Most tools used for prying, lifting,

and cutting leave distinctive marks. These

marks can be used to identify the source of

damage to doors, windows, cabinets, and other

secure locations. Often this is important when

ruling out that damage was caused by firefighters forcing entry for firefighting. Similarly,

marks on bodies can be identified in a similar

fashion. Exemplar tools and photographs are

used to establish similarities between the geometry of the mark and individual tools. Comparisons with tools or devices collected at the scene

can sometimes establish whether a specific tool

or device was responsible for the damage.

The kinds of trace evidence collected will be most dependent

upon the nature of the fire and the types of evidence

available. Sometimes trace evidence is disregarded in favor

of collecting accelerant residue samples. This may be a

mistake, especially when the presence of accelerants is

uncertain or the fire scenario is unclear. The best trace

evidence is often that for which an explanation is not

apparent. For instance, finding melted metal parts near a

point of origin may be curious but totally inexplicable at the

time they are collected. However, later analysis may later

not only provide an explanation but suggest a whole new

investigative approach.

11
A main problem in collecting trace evidence is the small

quantity of valuable trace evidence one would expect to find

in a considerable volume of useless fire debris. Determining

what will provide information of value may be quite difficult

due to the extent of damage and the quantity of debris

present. Destructive overhaul practices may also destroy

valuable trace evidence and produce excess debris. Sieving

debris in the field is one approach to this difficult problem.

However, sieves may damage some brittle specimens, rendering them worthless. Although time consuming, the best

approach is simply a thorough and systematic search of the

scene.

Unlike other material evidence which may simply be picked

up or extracted and placed in a container, fingerprints

require highly specialized collection techniques. In most

cases where fingerprint identification is necessary, either

special care must be taken to preserve the sample or the

fingerprints must be “lifted” in the field by a trained technician. For example, if an unbroken or defective Molotov

cocktail is found at the scene, usually the investigator will

want to identify the contents to determine if it is an accelerant and will want to identify the perpetrator(s) who built and/

or used the device. Preserving the sample for accelerant

analysis, however, will destroy the fingerprints on the

outside of the container. Therefore, either the contents must

be decanted into an evidence container for separate analysis

and the Molotov container preserved for latent fingerprint

analysis, or the prints must be lifted in the field and the entire

device shipped to the lab for analysis. Most investigators

prefer the former method.

Comparison Samples

Comparison samples are materials or objects which are

believed to be nearly identical to similar accelerant debris

samples with the exception that they are not believed to

contain accelerant residues. The purpose of such samples is

to identify and minimize oreliminate sources of interference

in the analysis of such samples. Examples of comparison

samples include the following:

New, unused evidence containers. Most

evidence containers yield no chromatographic

interference. However, some types of containers, like certain types of plastic bags and

specially coated containers, may give off

background vapors which may obscure

chromatographic analysis of evidence. New

types of containers and new lots of certain

container types, like plastic bags, should be

periodically submitted to the laboratory for

chromatographic analysis as comparison

samples. Likewise, collection materials may

sometimes present a source of interference. For

example, some absorbent materials for

controlling petroleum spills are unsuitable for

evidence collection because they have

been found to contain traces of contaminants.

Comparable accelerant samples. Often

investigators need to identify similarities

between samples of known flammable and

combustible liquids collected at the scene, from

those found in containers or obtained from other

sources near the fire scene, and flammable and

combustible liquid residues found in fire debris.

Flammable and combustible liquid residues in

debris samples may come from sources inherent

to the scene, or may be brought to the scene from

another source. For example, insecticides often

contain a petroleum-based carrier. Comparing

debris samples with samples of liquids from

these sources and with comparison samples of

materials similar to those present in the fire

debris may be a valuable method of

distinguishing between what was at the scene

before the fire and what was brought to the scene

to start or spread the fire.

Comparisons are often requested by fire

investigators when statements, evidence, or

circumstances indicate that an accelerant may

have come from a specific source, like a suspect’s

automobile or a nearby gas station. Forensic

science analysts can occasionally discriminate

between samples of similar materials as having

clearly different sources. However, if no

differences are found, the strongest statement

which can be made is that the samples may have

had a common source. This is due largely to the

marketing practices of the petroleum industry

and the near impossibility of accounting for

every possible source. Another possible

conclusion is that the samples belong to the

same or different classes of petroleum products

identifiable using gas chromatographic pattern

recognition. The best samples for such

comparisons are liquid-to-liquid samples. It is

much more difficult to determine a common

source using liquid samples and debris samples.

Comparable material samples. It is desirable to

collect samples of materials similar to those

found in the accelerant debris matrix that are

identical except that they contain no accelerant.

These materials, such as carpet or wood trim,

may often give off pyrolysis products which

partially obscure accelerant patterns during

analysis. A comparison sample should be

collected for every questioned fire debris

12
matrix.5

 The same can be true of generic

collection materials such as disposable diapers.

Comparison samples can be very important to making a

positive identification of a material. Whenever there is any

doubt about whether a comparison sample is needed, one

should be collected and submitted or the laboratory should

be contacted.

EVIDENCE PACKAGING

Evidence packaging is important for preserving and protecting evidence between the time it is collected and when it can

be analyzed in the laboratory. In some cases, it may take

several weeks to have evidence processed by a forensic

science laboratory. The nationwide war on drugs has

significantly increased the turnaround time for evidence at

most state and regional forensic science laboratories due to

the heavy drug-related caseload. Therefore, fire investigators should take particular care in packaging and preserving

evidence to maintain the quality of the sample, and prevent

release, deterioration, or contamination.

Accelerant Residue Samples

Because of the volatile nature of flammable and combustible

liquids, debris samples must be placed in vapor-tight containers. According to laboratory supervisors, the best container for flammable or combustible liquid accelerant residue and debris samples is unused metal paint cans with tightfitting friction lids. Laboratory personnel cite the advantages of the containers’ large openings in relation to overall

container diameter, vapor-tightness, rigid form, lightweight,

durability, lack of appreciable background interference

during analysis, availability, and range of available sizes.

Other containers have their uses as well; the container must

be compatible with the sample and the tests or analyses to be

performed.

Samples such as clothing or textiles may be too large for

metal cans. In such cases, many fire investigators have

found KapakTM bags to be a good substitute. These selfsealing bags have an exterior layer of polyester and an

interior layer of polyethylene. Many other types of plastic

bags and containers may not be well-suited to use as

accelerant residue debris containers. Polyethylene plastic

bags, paperbags, aluminum foil, mylar bags, and coffee cans

with plastic lids are not vapor-tight with respect to flammable and combustible liquids. Petroleum products will

pass through paper and polyethylene, and be lost to the

environment or contaminate other samples they are packaged with. Other types of plastic bags, such as KapakTM

 or

nylon, may tear if the debris sample contains sharp objects

such a glass or nails.

Liquid samples may be placed in small glass vials with

screw-top lids, not rubber stoppers. These containers should

then be placed inside a metal can filled with VermiculiteTM

to prevent the vials from breaking in transit.

Some fire investigators prefer glass MasonTM jars for collecting and preserving evidence. The primary advantages are

the availability of these containers at hardware, variety, and

farm stores, especially in remote or rural areas away from

central cities. With proper protection and packaging these

containers can be excellent for collecting and preserving

accelerant residue samples. The screw-top vapor-tight lids

work well and the wide mouth makes it easy to insert and

remove samples. Moreover, the sample remains visible,

permitting inspection without opening the container. However, some petroleum products and volatiles present in fire

debris may degrade the jar lid’s rubber seal, allowing vapors

to escape. One proposed solution to this problem is the

insertion of a layer of aluminum foil between the jar opening

and the lid.

The quantity of material needed to perform a successful

analysis is often misunderstood. Only a relatively small

quantity of a very concentrated sample is needed. The more

dilute or evaporated a sample, is the more material will be

required to perform a good analysis. Although small samples

may be adequate under the right circumstances, in general

it is better to collect a larger as opposed to smaller sample.

After all, it is often difficult to tell precisely where in a given

sample area the greatest concentration of accelerant will be

found. Samples should be collected at each location where

accelerant residue is suspected. A good sized sample will fill

a one quart or one gallon metal can one-half to three-quarters

full. Carpet samples should be about as wide as the can is

deep, and as long as the can is round. A good carpet sample

will fully line the interior of the can. When residue is

extracted from concrete, all of the absorbent material and a

small amount of concrete from the surface area where the

adsorption was performed should be collected and packaged

together. If a liquid is wiped or absorbed from another nonporous surface using a clean, dry absorbent textile material,

as much residue as practical should be collected and the

entire absorbent material submitted.

Trace Evidence

Trace evidence covers many different types of specimens

and samples, and therefore, packaging methods vary widely

as well. The packaging technique used must be compatible

with the type of evidence collected and the test(s) to be

conducted. Many trace evidence specimens will be analyzed by more than one technique.

Serological specimens and samples for latent fingerprint

examination should be sealed in brown paper bags or

13
carefully wrapped in kraft paper. Air- or vapor-tight containers will cause deterioration of such samples due to

bacterial growth of serological specimens. Latent fingerprints will be destroyed by moisture or petroleum products.

It is better to have the sample exposed to air than dissolved

by moisture or contaminated by bacteria growth.

Documents can provide valuable clues not only about what

happened but why it happened too. Questioned documents

should be packaged in clear, protective envelopes to avoid

wear and tear and protect latent fingerprints. Partially

burned or water-soaked documents should be placed on a

firm support, such as cardboard, poster board, dust pan, or

cake plate, and placed in a flat box for transport to the

laboratory.6

All types of trace evidence, especially device remnants and

unidentified debris, should be carefully described by the

investigator. Extra care should be taken to give the laboratory analyst any clues the fire investigator may have about

the article’s identity without presupposing any particular

conclusion. Likewise, the investigator should give the

analyst a clear idea of what he or she wants to know about

the item, e.g., latent fingerprints, blood type, physical match

with comparison sample, and so on.

Comparison Samples

Comparison samples should be packaged exactly the way

similar accelerant debris or trace evidence samples are

packaged. Comparison samples are submitted for the purpose of minimizing or eliminating interference from sources

other than an accelerant or identifying similarities between

“knowns” and “unknowns.” To ensure the greatest degree

of reliability, the practices used for processing and preserving comparison samples must be as similar to those used for

the target sample as practical.

Storage and Preservation of Evidence

With the delays in processing evidence growing in many

places around the country, proper storage is increasingly

important. Some agencies may find themselves responsible

for evidence samples due to delays in shipment, laboratory

backlogs, or samples returned from one laboratory awaiting

shipment to another laboratory. Under such circumstances,

fire investigators should be prepared to store, document, and

preserve the evidence in the same manner as it would be

while awaiting analysis at the laboratory. American Society

for Testing and Materials standard ASTM E1492-92, Practice for Receiving, Documenting, Storing and Retrieving

Evidence in a Forensic Science Laboratory details the

specific practices recognized throughout the forensic science community for maintaining the chain-of-custody and

preserving evidence samples before and after forensic analysis.

FORENSIC TECHNIQUES

Modern forensic science provides valuable tools for documenting and verifying the findings of field investigators.

Forensic science applies the principles of analytical chemistry and physics to the identification, classification, and

comparison of evidence samples collected by fire investigators for the purposes of determining the truth about fires and

their causes. These techniques often involve complex,

specialized equipment, but more importantly, they require

the competence and professionalism of dedicated field

investigators and laboratory technicians working together to

obtain and analyze the evidence.

Accelerant Identification

Most flammable and combustible liquids used to accelerate

the spread of a fire are products refined from crude oil. Crude

oil and its refined products, such as gasoline, kerosene, and

diesel fuel, are complex mixtures of thousands of different

organic compounds. These compounds are mostly hydrocarbons; that is, compounds containing only carbon and

hydrogen atoms. Gas chromatography is an analytical

laboratory technique used to separate mixtures of volatile

organic compounds, and therefore, is well suited for analyzing petroleum products recovered from fire debris samples.

Accelerant identification in the laboratory consists of three

steps:

Sample preparation, the process by which the

liquid is extracted or isolated from fire debris.

Instrumental analysis. Once isolated, a sample

is analyzed using gas chromatography (GC).

GC separates components of a mixture by

volatilizing the sample into a carrier gas stream,

which transports it through a column containing

a fixed absorbent phase. Upon emerging from

the column the fractions are ionized and

exposed to a detector which registers the

relative concentrations to permit analysis. The

concentration results are plotted on graph paper

as a function of time. This graph, called a

chromatogram, is interpreted by an analyst to

classify the material. GC is a good technique for

analyzing extremely small quantities of

complex mixtures.

Data analysis. The determination whether a

petroleum product is present in the sample, and

if so what the product is, is performed by

comparing the sample chromatogram with other

chromatograms of known products or

comparison samples to produce an

identification.

14
Sample Preparation

The isolation and recovery of a sample is the first and most

important step in identifying a possible accelerant residue

using gas chromatography. There are five different methods

for recovering petroleum products from fire debris:

Direct headspace - sampling from the vapor space

in the container above the debris sample which

may either be heated or at room temperature.

Static head space - placing a material such as

activated charcoal in the debris which will adsorb

the volatile compounds present.

Dynamic head space - sweeping air into the container then extracting it over some material such as

activated charcoal which will adsorb the volatile

compounds present in the vapor stream.

Solvent extraction - placing a solvent such as

carbon disulfide (CS2) in the container.

Steam distillation - no longer used because it the

least sensitive and most time consuming.

Static and dynamic headspace techniques are among the

most commonly used since they are very sensitive and

require little labor. American Society of Testing and

Materials standards have been adopted to document each of

these procedures.

ASTM E1385-90, Standard Practice for Separation and Concentration of Flammable and Combustible Liquid Residues from Fire Debris Samples

by Steam Distillation.

ASTM E1386-90, Standard Practice for Separation and Concentration of Flammable and Combustible Liquid Residues from Fire Debris Samples

by Solvent Extraction.

ASTM El388-90, Standard Practice for Sampling of Headspace Vapors from Fire Debris

Samples.

ASTM E1412-91, Standard Practice for the Separation and Concentration of Flammable and Combustible Liquid Residues from Fire Debris Samples

by Dynamic Headspace Concentration.

ASTM E1413-91, Standard Practice for Separation and Concentration of Flammable or Combustible Liquid Residues from Fire Debris Samples by

Passive Headspace Concentration.

Instrumental Analysis

National standards for forensic analysis of fire debris have

recently been adopted which recognize GC as the only

acceptable means of identifying flammable or combustible

accelerant residues. In recent years, improvements have

Table 4.1

Comparison of Gas Chromatographic Techniques

Advantages/Strengths Disadvantages/Weaknesses

Capillary column gas chromatography offers best

resolution over shortest time of current analytic

techniques

When used with mass spectormetry, interference can

easily be filtered out permitting positive class specific

identification

When used with data analysis routines (pattern

recognition programs), operator bias can be reduced,

cost-effeciency improved, and statistical control

achieved.

Has difficulty identifying highly volatile substances

and polar solvents due to lack of generally acceptable

enrichment techniques

Mass spectrometry adds to the time and cost associated with processing samples, and is therefore, seldom

used.

Without data interpretation, analysis is still carried

out by visual interpretation and comparison

Source: Bertsch, W., Zhang, Q.W., and Holzer, G. (Sept. 1990), “Using the the tools of chromatography, mass

spectormetry, and automated data processing in the detection of arson, “Journal of High Resolution

Chromatography, Vol. 13, No. 9, p. 601.

15
Table 4.2

Accelerant Classification Scheme

Accelerant Class and Category Approximate Boiling Point

Range [°C]

Examples

1 Light Petroleum <120 Petroleum ethers, pocket lighter fuels,

Distillates (LPD) rubber cement solvents, skelly solvents,

lacquer thinners, VM & P Natptha

2 Gasolines 50-220 All brands and grades of automotive

gasoline - including gasohol, some

lantern fuels

3 Medium Petroleum 60-200 Charcoal starters, paint thinners (Oil

Distillates (MPD) based), mineral spirits, “drycleaning”

solvents, torch fuel

4 Kerosene 90-290 No. 1 fuel oil, jet-A (aviation) fuel, inset

sprays, charcoal starters

5 Heavy Petroleum 210-410. No. 2 fuel oil, diesel fuel

Distillates (HPD)

0 Unclassified Variable Single compounds such as alcohols,

acetone, or toluene, and xylenes,

isoparaffinic mixtures, some lamp oils,

camping fuels, lacquer thinners, duplicat.

ing fluids, and others.

been made to this procedure to reduce interference from

background sources within the fire debris matrix and improve reliability. These include the addition of mass spectrometry and pattern recognition computer software.

To understand the application of gas chromatography to fire

investigation, and the impact of these improvements, it is

important to understand a little more about how a GC works.

Petroleum products contain hundreds of different organic

compounds, mostly hydrocarbons. Each hydrocarbon is

characterized by a specific boiling point. This property

differs for compounds based on their size and chemical

structure. Gas chromatography can be used to separate

mixtures based on the boiling points of the components of

the mixture. A petroleum product or isolated sample is

injected with a syringe into a heated injection port where it

is instantly vaporized to the gaseous phase. The vaporized

mixture is swept into a column by an inert gas, usually

helium or nitrogen. As the hydrocarbons travel down the

column, they are separated according to boiling point. The

more volatile compounds having lower boiling points travel

down the column faster, than the high boiling point, less

volatile compounds.

As each compound leaves the column, it passes by a

detector. The most common detector type used in forensic

gas chromatography is the flame ionization detector (FID)

because it is best at detecting organic compounds and is

especially sensitive to hydrocarbons. As a compound passes

through a hydrogen flame in the detector, it is ionized. The

presence of charged particles, ions, within an electrode gap

causes a current to pass through the gap. The current is

measured and amplified by an electrometer, which sends a

signal to a recording device, such as a mechanical chart strip

recorder or a computer. The resulting chart is known as a

chromatogram. This chart contains many peaks, each of

which correspond to at least one chemical compound.

Collectively the peaks form a pattern. Patterns of chromatograms of samples isolated from fire debris are visually

compared to patterns of chromatograms of known petroleum products to obtain an identification.

To’ ensure reliability, repeatability, and consistency, the

forensic science community has developed guidelines for

conducting laboratory analyses of fire debris. These procedures are documented in ASTM E1387-90, Standard Test

Method for Analysis of Flammable or Combustible Liquid

Residues in Extracts from Samples of Fire Debris by Gas

Chromatography. Another standard, ASTM E1389-90

Standard Practice for Cleanup of Fire Debris Sample’

Extracts by Acid Stripping, covers one cleanup method to

remove interfering compounds arising from the sample

matrix.

16
Data Analysis

Most chromatograms are still visually analyzed or “eyeballed” to ‘identify’ the material present in the sample.

Although each petroleum product produces a distinctive

chromatogram based on its chemical composition, background volatiles found in most fire debris may cause even

similar fire debris samples to produce different chromatograms.

Pattern recognition is the method used to identify petroleum

products recovered from fire debris. Forensic laboratories

have examined hundreds of commercially available petroleum products and found their chromatographic patterns fall

into the five categories shown in Table 4.2. Because of the

blending processes used to manufacture automotive gasoline, it produces a pattern unique enough to be in a class of

its own. The other classes of products represent “cuts” off

the distillation tower at the refinery. Note that these classes

contain a variety of commercial end use products. It is not

possible for the forensic science analyst to determine what

the exact commercial end use was of a product detected in

a fire debris sample,. For example, the same medium

petroleum distillate (MPD) may, be sold commercially as

either paint thinner, mineral spirits, a dry cleaning solvent,

or a charcoal lighter fluid. The fire investigator must keep

in mind that a petroleum product detected in fire debris may

come from a variety of sources, some of which are inherent

to the scene.

The sample preparation techniques used to recover petroleum products from the fire debris also recover combustion

and pyrolysis products from the sample matrix. The sample

matrix may consist of wood, carpet, or other furnishing and

building materials in addition to flammable or combustible

liquid-residue. The presence of these materials may complicate the chromatogram to a point where the identification of

a petroleum product is not possible due to interference from

pyrolysis products. In some cases, using a more selective

and specific detector can help. One detector used for this

purpose is the mass spectrometer. Where the flame ionization detector merely detects the presence of organic compounds, the mass spectrometer can determine what specific

chemical compound is coming out the end of the GC column.

Using various computer data manipulation routines, gas

chromatography/mass spectrometry (GC/MS) can sometimes identify petroleum products in samples containing

interfering peaks in the GC-FID chromatogram.

GC/MS is also useful for identifying products ‘that are

unusual or contain only a few chemical compounds and

therefore do not produce a distinctive pattern. One example

is alcohol. Grain alcohol (ethanol), wood alcohol (methanol), and rubbing alcohol (propanol or iso-propanol) all

consist of a single chemical compound, and will produce

only one peak on a GC-FlD chromatogram. GC/MS on the

other hand, can identify that the compound is indeed, for

example, ethanol. Being volatile and water soluble, alcohols are not likely to be found in fire debris samples. If an

investigator thinks alcohol may have been used to set a fire,

he or she should alert the laboratory analyst so the proper

steps can be taken to recover and identify the material in

debris samples.

Computer pattern analysis provides another useful way of

identifying accelerants from complex chromatograms.

Computers and specialized software employing complex

statistical techniques may be used to compare the sample

chromatogram with othersstored in the computer’s data files

and analyze the correlation between them. This technique

is limited, however, by the complex software required to

perform the calculations and the fact that mini- or mainframe computers are required to perform the calculations.

To date, computer pattern recognition has been applied to

identification of the source of oil spills, but has not been

widely adopted for use in the analysis of data from fire debris

samples.’

After the chromatogram has been generated, it is interpreted.

Five categories are used to classify flammable and combustible liquids. These are illustrated in Table 4.2. Fire

investigators often request that forensic science laboratories

identify a specific product such as gasoline by brand or

grade. The nature of gasoline refining and marketing

currently make this impossible. It is not practical to describe

a sample in terms more distinctive than these fivecategories:

light petroleum distillates, gasoline, medium petroleum

distillates, kerosene, and heavy petroleum distillates.

Examination of Trace Evidence

Examination of trace evidence is conducted either to identify the material or its source, or associate the item or

specimen with another sample. A vast array of techniques

is used to analyze trace evidence. Most of these techniques

involve the careful, detailed examination of the article or

specimen. Special equipment may be used to enhance the

analyst’s visual capabilities and produce permanent records

or images of the observations made. The most popular

instruments for analyzing trace evidence are the magnifying

glass and stereo microscope. Scanning electron microscopes, metallurgical, x-ray diffraction, infrared, ultraviolet, and other techniques are also frequently employed.8

An example of the power of trace evidence examination is

illustrated in the techniques employed in the investigation of

a bombing. Pipe fragments from a device may be recovered

during on-scene investigation and shipped to the laboratory

for examination. During examination, the analyst carefully

and systematically searches the surface for chemical residue. If a particle of smokeless powder is discovered,

its shape, color, and texture are classified and compared with

17
the characteristics of smokeless powder samples on file with

the laboratory to make an identification. The pipe fragments

themselves are compared with exemplars or samples of

undamaged pipe from a wide variety of manufacturers also’

kept on file in the laboratory. Finally, the fragment is

examined for the presence of latent fingerprints. Any prints

found are lifted and classified. The fingerprint classification

is then compared with those on file in a national database and

if a “hit” is obtained, the actual fingerprint samples are

compared.

Other types of evidence undergo similar examination processes. For example, an analysis of a questioned document

may be conducted to discern what information it contains

and determine its origin. Likewise, latent fingerprints may

be lifted from such documents. Forensic specialists known

as “questioned documents examiner” analyze the origin and

preparation of documents. Latent fingerprint examiners

identify, classify, and analyze fingerprint evidence. To

ensure that both procedures produce the proper results, the

document should be examined by the questioned documents

examiner first. This way any damage caused during the

latent fingerprint examination will not obscure or destroy

the evidence of the document’s origin or method of preparation or alteration. Serological samples are chemically

analyzed to identify blood type, perform DNA fingerprinting, or determine specimen morphology for comparison

with samples from suspects.

Comparison of Evidence Samples

Comparison samples are processed in the same manner as

the counterparts to which they will be compared. The

collection and analytic techniques should be as similar as

possible to ensure validity and reliability.

PHOTOGRAPHIC PROCESSING AND

ANALYSIS

Photographic documentation of the fire scene is perhaps the

most common of all analytic techniques. The adage that “a

single picture is worth a thousand words,” is certainly true

when documenting or analyzing a fire scene.

This section discusses the types of equipment and supplies

used to document fire scenes visually, and the application of

photographic evidence is considered. For a detailed discussion of how to photograph the fire scene, see the excellent

references on this subject in Chapter 6.

Fire Scene Photography

Without going into detail about how to take pictures of the

fire scene, it is important to understand what to photograph.

Photographs should serve as a visual record of the circumstances surrounding the origin and cause of the fire. The

photographic record should, to the extent practical, present

a visual report of the fire.

Two general rules of thumb should apply to fire scene

photography:

‘Work from the general to the specific. Each

photographic sequence tells a story. A good story

always describes the setting in detail. The best

composite of the fire scene story is told by weaving

the details in close-ups into the larger mosaic of the

fire as a whole.

‘Don‘t be afraid to take too many pictures. Photographic film and processing are a lot cheaper

than a lost opportunity to clear a case. Failing to

document a key piece of evidence or document

how it was discovered or processed can damage an

otherwise credible case. Reason should prevail in

deciding what to take pictures of or how many to

take, but it is usually better to err on the side of

more rather than less. Besides, there are plenty of

ways to economize in the way the photographs are

taken and processed rather than simply not taking

them at all.

During the fire -- Fire scene photographs taken during the

fire can be a valuable adjunct to the investigative record,

especially if they can be tied to a particular point in time. Fire

investigators can use these pictures to obtain a better understanding of the fire’s development while it was in progress.

Vehicle-mounted videotape cameras are another way of

producing a detailed visual record of the fire while it is still

in progress. Many police agencies have recently begun

installing these devices in large numbers to record police

activity like traffic stops. Many of these cameras also come

equipped with time and data stamps.

Exterior -- Photographs of the outside of the building

document what the firefighters themselves may have seen

when they arrived. Smoke stains, thermal damage, and

structural collapse all document what effects the fire may

have had on the inside, as well as the potential effects on

adjacent structures. Exterior photographs should illustrate

the following key features:

Property address or location

Relationship to adjacent properties or structures

Condition on each side beginning with the

“front,” that being the side to which the fire

department first responded

Conditions at specific locations where smoke or

fire vented or collapse occurred

18
Figure 4.3

Anytown Fire Department

Fire Investigation Unit

Photographic Log

Address: 4321 W. Broad Street Investigator: B. Dano Date/Time: 1-1-91 12:01 am

Photo No.

(Roll/ Subject Exposure Flash

Exposure) Information

A/1 Exterior front (side 1) from across street, 35 mm Wide X

Note: Heavy fire damage above front door f2.8 - 1/60

with smoke staining and radiating vee pattern.

A/2 Exterior east side (side 2) from front porch of

adjacent dwelling. Note: Broken windows on

first and second floors, smoke stains over 1st

floor.

50 mm X

f1.7 - 1/60

A/3 Exterior rear (side 3) from alley. Note: No 35 mm Wide X

fire damage, door forced open, windows f2.8 - 1/60

broken on first floor.

A/4 Exterior - closeup rear door from back porch. 70 mm Zoom X

Tool marks look like FD forcible entry. f16 - 1/60

A/5 Exterior west side (side 4) from side yard of 35 mm Wide X

adjacent property. f1.7 - 1/60

A/6 Exterior - front entrance door open. Taken 50 mm X

from porch. Note: High heat damage and f3.5 - 1/60

diagonal burn pattern.

A/7 Exterior - closeup on front door lock and 70 mm Zoom X

hardware from porch side. f16 - 1/60

Entrances -- Each entrance to the building should be

carefully examined and photographed to document its condition at the time the fire occurred and during the incident.

Close-ups of tool marks will help corroborate witness accounts and may aid forensic science analysts in determining

what tool(s) may have caused the damage. Locking and

security hardware should be carefully photographed to

document how the scene was secured and how it may have

affected occupant egress.

Interior -- Photographs should document the inside beginning with the areas of least damage and working toward the

area of heaviest damage. This is generally the preferred

investigative sequence as well. Photographing as you go

helps tell the story of how the fire was investigated and

confirms that proper investigative procedures were employed throughout.

Photographic Log -- It is a good idea to keep a log of what

was photographed, where it was photographed from, and

how the picture was taken. This information may be

captured textually, verbally, graphically, or by a combination of these means. It is often difficult to fully understand

what a photograph was intended to illustrate if this information was not recorded. Even properly exposed photographs

are sometimes very difficult to interpret due to the nature of

the subject. Likewise, fire scenes often produce extremely

poor photographic conditions. Where a photograph does not

come out properly, it is often helpful to know why it did not.

The photographic log will also documents the sequence the

photographer used to approach the subject investigated and

photographed. Since photographs appear in time sequence

on a roll of film, this is a useful way of demonstrating that

a systematic method was used to investigate and document

the fire scene.

19
Figure 4.3 details a few entries from a good written photographic log. Note that it contains an identification of the

photograph as it appears on the roll; a description of what is

in the picture; where it was taken; what lens, aperture, and

exposure were used; and, whether or not it was taken with a

flash. The same information can be read into a small tape

recorder or into the microphone of a video camcorder. Many

fire investigators also produce detailed floor plans to document what was photographed and where the photographer

stood while taking the picture.

Photographic Equipment and Techniques

Almost any camera is better than no camera. Taking good

pictures is more a matter of the photographer’s skill than the

quality of the camera. Today more than ever, the introduction of low cost high-quality photographic equipment and

high-speed film have made fire scene photography more

practical than ever before, even for small departments and

those on tight budgets.

Cameras, Lenses, and Accessories -- Most fire investigators

seem to prefer 35-mm single lens reflex (SLR) cameras with

interchangeable lenses. These cameras give the user control

of aperture, film speed, shutter speed, and flash. Fire

investigation units on tight budgets, fire company officers,

and inspectors have found the new generation of 35-mm

automatic cameras with fixed lenses quite useful. Many of

these cameras come equipped with so-called data-backs

which imprint the time or date on the photographic image.

Some even adjustable lenses which provide a range of focal

lengths from close-up to zoom. More recently, automatic

settings and features have been combined with the traditional features of SLR cameras to give the photographer a

full range of creative options. These cameras have made

high-quality photographic capabilities accessible to almost

all departments and make fire scene photography increasingly practical.

When selecting a camera for fire scene use, the fire scene

environment should be a prime consideration. Dust, dirt,

water, and corrosive gases and vapors may all damage the

camera and accessories. Most professional SLR cameras

can take this kind of abuse if they are handled with adequate

care and cleaned and maintained regularly. Lenses will be

one of the most vulnerable parts of the camera, and should

be covered when not taking pictures. To provide protection

during photographing, a clear or ultraviolet filter should be

attached to prevent the lens’ surface from being scratched by

fire debris. It is much cheaper ($15 - $20) to replace a filter

than a lens ($75 on up).

As already mentioned, fire scenes are not the best photographic environments. Fire and soot blackened surfaces

make getting good contrast extremely challenging. Flash

units may be particularly susceptible to water damage Flash

units should provide adequate power to fully illuminate even

very dark subjects.-Many camera kits come with their own

flash units, but these are usually designed for “normal’?

picture taking; more powerful units may be needed for fire

scene work. Keeping power supplies and flash units covered

when not taking pictures and avoiding water spray at all

times are generally good rules of thumb.

Many cameras now come equipped with built-in automatic

winders. Some photographers use external motor drives

and/or automatic winders to advance and rewind the film.

Like other motor driven devices, motor drives and automatic

winders may be highly prone to shock and impact damage.

External motor drives and automatic winders run approximately $150 to $200.

A tripod or monopod makes an excellent accessory. Large

apertures and slow shutter speeds are often required due to

the poor light conditions and contrast found on the fire scene.

These conditions can cause pictures to blur easily. A tripod

or monopod provides an ideal support from which to shoot

under these difficult conditions. A good tripod costs about $100.

Again, fire scene conditions conspire against otherwise

good photographers. Poor lighting and contrast will make

a flash a necessity rather than an option. Under normal

lighting conditions a light meter will help the photographer

determine the best shutter speed and aperture to use to obtain

a given exposure. Most flash units require that a single

shutter speed be used in order to maintain synchronization

between the shutter and the flash. A flash meter will do the

same thing as a light meter except it works with a flash.

Instead of reading the amount of ambient light available, a

flash meter measures the amount of light reflected by the

subject under flash lighting conditions and recommends the

appropriate aperture to achieve proper exposure. Good flash

meters start at approximately $120 and run into the neighborhood of $350.

Film -- A wider variety of film is now available. Moreover,

the high speed films of today produce higher quality images.

A great many options are now available to the fire investigator for documenting the fire scene. The photographic and

fire investigation texts referenced in Chapter 6 include

extensive discussions of film speeds and types.

Most fire investigators report that they prefer 35mm color

slides for fire scene photography. Color slides have several

advantages over color and black-and-white prints.

Cost less to process

Better image quality

Ability to produce duplicates and prints from

same slide

Ability to project images for courtroom

presentations

20
The single greatest drawback of slide film is that it is slightly

more expensive to produce prints from slides than from

negatives. Since a slide is a positive image, an internegative

must be produced before a print can be made. Usually this

results in only a slight loss of color and image quality.

Although slides and prints can be produced from other

photographic media, the duplication process can be quite

complex. Moreover, with each step in the reproduction or

duplication process, some loss of clarity or color contrast

occurs. Slides produce the best reproduction results for the

money.

Other options are available which produce better results for

certain situations. For example, print film provides the

photographer with wider latitude than slide film in terms of

exposure. Since the final product is a photographic print, an

under exposed negative can be corrected simply by exposing

the print for a longer period and vice versa. Another option

has become available in the past several years which yields

both prints and slides. At least three mail-ordervendors have

begun offering dual media films which produce image

quality comparable to slides while providing the flexibility

to produce a print without having to create an internegative.

Instant photography has gone from fad to mainstream.

Today, instant photography has become a popular tool for

capturing images quickly when only a single copy is required. The drawbacksof most instant photography are poor

depth of field, poor image quality, poor adaptability (most

of the cameras only have a single, fixed lens),, and film

expense. However, some evidentiary purposes lend themselves particularly well to this technique. The most popular

manufacturer of instant cameras and films has developed

products aimed specifically at capturing macro images of

small objects. Moreover, they have developed services for

duplicating their photographs when the need does arise.

Generally this involves taking a picture of your picture under

very controlled conditions. Nonetheless, instant photography remains one of the less popular fire scene photographic

techniques.

Video Camcorders -- Video camcorders have

become one of the most popular items on fire

investigation unit wish-lists. Videotape offers

several advantages over traditional still photographs. Perhaps the most important of these is the

ability to capture the whole fire scene in context.

Each videotape can act as a guided tour of the fire

scene. As lay people become more and more

familiar with videotape in their own homes, they

may be expected to become more impressed by it

as jurors when it is used to document the fire scene.

Another of videotape’s advantages may also be a weakness.

Most videotape camcorders offer the ability to record sound

as well as visual information. As such the accounts and

descriptions of the investigator may be captured as the scene

is processed. Consequently, fire investigators using videotape should be very careful about what they say while the

camera is “rolling.” Preliminary conclusions and statements

about suspects or suspicions about probable cause could

become part of the record. Videotape used in the preparation

of an arson case can be subject to the rules ofdiscovery, and

these statements can then be used to attack the investigator’s

credibility and independence.

The ability to edit and enhance videotape is another advantage with potential drawbacks. Editing videotape gives the

investigator the ability to “cut to the chase,” and bypass

unimportant details so long as the complete unedited version

remains accessible to the defense. Titling and captioning

videotape gives the fire investigator the ability to reinforce

or clarify key points about the information on the videotape

and can be powerful tools in the use of videotape in the

courtroom. However, the videographer must be ready to

demonstrate that the images presented, after editing, titling,

or captioning, remains an accurate and factual representation of the fire scene or subject.

Additional advantages of videotape are its ease of duplication and case of presentation. Several copies can be made

from the same original. With good duplication facilities the

number of copies from a single original is virtually limitless.

Also, an almost unlimited number of people can view the

same videotape, either individually or simultaneously depending on the sophistication of the broadcast capabilities.

The two most popular formats currently are 1⁄2inch VHS and

8-mm. Whichever format is selected, the final product

should be compatible with the intended playback equipment

or duplication facilities should be available. The expense of

videotape as a fire scene tool ranges from a little less than

$1000 for a good camcorder to several thousand dollars for

advanced editing, titling, captioning, and broadcast capabilities.

Using Fire Scene Photographs

Fire scene photographs are generally taken to document the

conditions found during the investigation so that they can be

preserved after the scene is destroyed, altered, or restored.

Their principal use is in presenting a visual account of the

fire and its effects. Recently a serious debate has emerged

within the fire investigation community about whether or

not fire scene photographs can be used in lieu of on-scene

investigation to evaluate certain conditions related to a fire.9

Those who support analysis of photographs in lieu of onscene investigation readily admit that it is a poor substitute

for on-scene investigation. It is sometimes difficult to tell

whether a photographic detail comes from the photographic

process or was something real on the fire scene. The value

of photographs is obviously limited to that which they

specifically portray. In many cases, this information, out of

context, is meaningless.

2 1
Nevertheless, the use of photographs to analyze events after

the fire scene investigation is complete is widely recognized

as a legitimate investigative technique. In forensic analysis,

photographs are often the only record of the position or

condition of an object before it was collected or recovered

for analysis. Consequently, the analysis of photographs

should never be dismissed out-of-hand. However, photoanalysis should never replace thorough on-scene investigative efforts either.

Fire scene photographs and visual information can be presented a number of different ways with dramatic appeal and

effect. The format and presentation chosen should try to

satisfy each of the following conditions:

Accuratelyrepresent the conditions as they exist

in the field when the image is captured

Accurately portray the relationship between the

subject and its environment

Produce adequate contrast and detail to permit

all important features to be clearly discerned

Clearly depict the subject so it can be easily

understood by those who must use it

The last point is the easiest to overlook. Fire scene photographers often view themselves as the primary audience for

their pictures. However, if videotape or photographs are

taken for evidentiary purposes, many other viewers must

also use the images. A forensic science technician may

make a positive identification of an object which is crucial

to the case on a good photograph. Civil trials may develop

months or years after accidental fires are investigated. An

attorney may decide how to proceed with a defense based on

the photographic record. And a jury may decide the guilt or

innocence of a defendant on the strength of photographic

evidence. Even non-evidentiary photographs are often

viewed by many people. Keeping the subject and the

viewers in mind will make a better photo or video image

regardless of the equipment used.

ENDNOTES

1. Sanderson, J.L., Ballict, C. A. and Balliet, M. A. (March

1990) “Sampling Techniques for Accelerant Residue Analysis,” Fire and Arson Investigator, Vol.

40, No. 3, p. 36.

2. Dietz, W. E. (June 1991). “Physical evidence of arson:

Its recognition, collection, and packaging, “Fire

and Arson Investigator, Vol. 41, No. 4, p.35.

3. Ibid., p. 35.

4. Ibid., p. 34.

5. Ibid., p. 36.

6. Ibid., p. 39.

7: Ibid.

8. Custer, R. L. P. (1991), “Fire Loss Investigation, “Section

10/Chapter 1, Fire Protection Handbook, 17th ed.,

Quincy, MA: National Fire Protection Association, p. 10-7.

9. Smith, D. M. (Sept. 1990), “Investigation of fire through

photographs! Impossible?“, Fire and Arson Investtigator, Vol.41, No. 1,(pp. 59-60). Wagner, R. W.

(March 1991) “The investigation of fire through

photographs! Yes, impossible!“, Fire and Arson

Investigator, Vol. 41, No. 3, (pp. 58-59) and

Sanders, D., ibid., (p.60).

22
Chapter 5 - COMPUTER SYSTEMS

Many of the public sector pioneers of information processing used to rely on mainframe and minicomputers for their

information processing needs. While they still have their

place, the computing power that once required a dedicated

mainframe and a staff of programmers is accessible to

anyone who can afford a personal computer and learn to use

available software packages.

Personal computers have gained widespread acceptance in

the fire investigation for managing data, writing reports,

preparing diagrams of fire scenes, analyzing numerical data

like financial statements and fire statistics, preparing graphics, and communicating with remote computers to share

information or conduct research. As the number of agencies

using computers has grown, so have the number and type of

applications to support their needs. This section discusses

specialized applications for fire investigation, as well as the

basics of off-the-shelf software that may be useful to fire

investigators.

HARDWARE

Before discussing the software that makes a computer

operate, it is necessary to have a basic understanding of what

constitutes a computer system. Regardless of the type(make

or model) of computer, every system consist of five main

components:

Central processing unit (CPU)

Random access memory (RAM)

Storage device(s), e.g., disk drive, hard disk

drive, floppy disk drive, optical disk drive, tape

drive

Input device(s), e.g., keyboard, mouse or other

pointing device, text or graphics scanner

Output device(s), i.e. video display terminal

(VDT), printer, plotter, modem

The make, model, operating system, memory, display, and

output devices (peripherals) must all be compatible with one

another to operate properly. And all of these variables have

some impact on what software your computer will run.

Ideally, the decision about what hardware to use should

come after identifying and, defining the task or tasks for

which the computer system will be used. The use of the

computer will in turn establish what kind of software will be

required to perform that task. By defining criteria for

performance of these tasks, such as speed, ease of use, and

price, decisions can be made about the system to purchase

- including both hardware and software.

Many agencies have already made the leap to computers. In

these casts, care must be taken in selecting new software to

ensure compatibility with the system hardware already in

use. As new software comes on the market, many users find

it necessary to upgrade the memory, display, or storage

capabilities of their systems to take advantage of new

software features.

APPLICATION PROGRAMS

Computers are far from being “thinking machines.” Actually, computers themselves are quite dumb, nothing more

than a collection of inanimate parts. If computers are so

dumb, how do they do such powerful things? The answer lies

in the software which brings the inanimate parts to “life.”

Essentially, someone else has had to do the thinking. Application programs are the answer. Unless you are a computer

programmer, or have the budget to hire one, you probably

use application programs for everything your computer

does. Most application programs for personal computers fall

into one of five major categories:

Word processing

Database management

Spreadsheets

Graphics

Communications

As this list illustrates, these programs provide you with the

tools to perform a wide variety of tasks. Most fire investigators will probably find the existing application programs

quite capable of servicing their computing and dataprocessing needs. Word processing, database management, number

crunching, drawing and graphics, and electronic communications are no different for fire investigation than the same

tasks in other disciplines.

Off-the-shelf application programs can be useful tools of the

fire investigation trade. Like other tools, they are only as

effective as the person using them. Application programs

only instruct the computer to perform those tasks you

request. Therefore, training and practice are required.

Although you do not need to be “computer literate” to use

the most current application programs, most fire investigators will find that a modest investment of time is required to

become proficient. The emphasis on “user friendly” programs for all applications has produced programs which

most fire investigators will find useful and easy to learn and

use in a minimum of time. Moreover, the overwhelming

majority of fire investigation computing can be performed

using the off-the-shelf application programs. For those who

still find the personal computing intimidating, low cost

23
short-courses, seminars, self-instruction videocassettes, and

tutorials are available.

Word Processing

Word processing or writing programs allow you to interact

with your computer to product written records and documents. Modern word processing and desktop publishing

(DTP) programs incorporate features formerly restricted to

typesetting machines. The major advantages of word processing programs over typewriters and handwritten documents are editing, appearance, and space. Word processing

software permits the writer to edit and modify text before

printing. Revisions can be incorporated without producing

a whole new document. This alone is a major labor-saving

advantage. Advanced editing and formatting features, now

part of most programs, make it easier to produce higher

quality documents and publications with greater “eye-appeal.” Most programs now incorporate features for viewing

the document as it will appear on the printed page without

wasting a sheet of paper. For the investigator, the appearance of a document can be almost as important as the content

when it is used to influence or convince a prosecutor or jury.

Advanced formatting and typesetting features and the use of

graphics in documents make it easier to demonstrate the

logic of arguments and reinforce the writer’s credibility.

Finally, computer generated records take up far less space

than paper documents. One floppy diskette can often store

hundreds of pages of information.

The disadvantages of word processing software are relatively few, the most commonly cited ones being the difficulty learning how to use a particular system, the cost of the

program, and cross-compatibility between different platforms and applications. In general, it is both possible and

relatively easy to minimize any one or more of these

disadvantages through informed shopping. The key to

finding the right software at the right price is knowing what

you need to do, what you want to do, and what you are willing

to pay to get the job done. The more you are willing to spend

the more you will be capable of doing. Most word processing

programs retail between $250 and $500. Desktop publishing

programs anchor the upper end of the price spectrum,

weighing-in at about $900. Concerns about the userfriendliness of a program and the quality of customer support

can usually be addressed by interviewing other users or a

quick survey of the popular computer-oriented media.

Database Management

A database is nothing more than a collection of information

about a particular topic or subject. Database management

software permits large amounts of data to be stored efficiently and allows that data to be efficiently sorted, analyzed

and reported on. Moreover, many programs permit the user

to use the trends and relationships among these data to

predict the course of future activity. Although most database

programs are somewhat more compIicated to use than word

processing programs and require some planning and training

to use properly, the dividends they pay will become clear as

soon as the system is put to use. Most off-the-shelf database

software runs in the $200 to $500 price range. Custom

designed software for fire investigation and fire reporting

costs between $1,000 and $5,000.

An example of a database is a fire department’s collection

of information about fires and emergency responses obtained from fire incident reports completed by company or

chief officers. Most fire investigators are probably familiar

with database programs for entering and reporting on such

fire incident data. Commercial products for this application

abound. An excellent low-cost program is the National Fire

Incident Reporting System (NFIRS) software, which is

available for the cost of materials and shipping. Copies of

the NFIRS software can be obtained by writing the United

States Fire Administration, Office of Fire Data and Analysis,

16825 South Seton Avenue, Emmitsburg, Maryland 21727.

The United States Fire Administration also supports a fire

investigation software package known as the Arson Information Management System (AIMS). AIMS is a personal

computer database system for managing arson investigation

data. AIMS is in use by hundreds of fire investigation units

nationwide. The profiles of arson-prone buildings are

developed by analyzing information about incendiary fires

entered in the case file database. This information can then

be used to assess the probability that similar buildings

entered in another database will be arson targets. Copies of

the software are available from the Unites State Fire Administration, Office of Fire Prevention and Control, 16825

South Seton Avenue, Emmitsburg, Maryland 21727.

Spreadsheets

Spreadsheets are programs for collecting and analyzing

data. Spreadsheets organize the data into tables. These

tables consist of rows and columns. Cells are the junctions

between vertical columns and horizontal rows. The data in

a cell represents something that column and row have in

common. The rows or columns may represent records,

classes, or categories or any other piece of information

common to other things appearing in the same dimension

(horizontal or vertical). The other dimension is used to

represent another element, class, category, or record common to the same piece of information.

The value of a spreadsheet is the ability to rapidly calculate

and manipulate information which is related logically or

mathematically. To do this, however, the user must have

some idea what relationships logically exist between the

information in the rows and columns. A spreadsheet simply

provides a convenient and rational way to organize and

24
Figure 5.2

Sample Fire Incident Data Spreadsheet

manipulate that information. Manipulating data usually

means performing logical, statistical, or arithmetic functions on related cells, rows, or columns. Most spreadsheets

incorporate features for illustrating these relationship graphically on charts, graphs, and diagrams.

Graphics

Graphics packages include programs for producing, capturing, and manipulating images. These images may be line

drawings, three dimensional projections, still photographs,

animation or video sequences. Graphics is perhaps the most

rapidly advancing area of all computer applications. The

growth of this segment is directly related to the power of

images to illustrate abstract and complex ideas. Most fire

investigators would probably agree that illustrating the

relationship between a fire, a building and its contents, and

people, including the occupants, witnesses, and firefighters

is a complex task. This makes fire investigation an ideal

application for graphics programs. The most useful programs for fire investigators are drafting or drawing programs

and business graphics.

Computer-aided drafting and design (CADD) packages are

excellent programs for producing scaled line drawings of a

fire scene. Generally, these programs permit users to

produce very sophisticated drawings with great precision.

However, many of these programs are highly specialized

and require training and practice to use effectively. Simple

CADD packages begin at $200. More complex programs for

producing three dimension drawings, animated models, and

full-color renderings are at the upper end of the cost range

at about $4000.

Business graphics programs take the graphics capabilities

imbedded in products like spreadsheet programs several

steps further. These programs permit the user to produce

presentation quality graphics in the form of transparencies,

color slides, graphic insects in word processing or DTP

documents, and self-running slide shows on the computer

screen. Most of these programs also give the user all the tools

needed to produce simple line drawingsbut without the same

level of sophistication present in the output of CADD

programs. Line drawings produced with these programs are

usually quite adequate for most fire investigation reports.

Many of the business graphics programs also have the

capability to convert graphic images captured or produced

by other programs for use in their application. A good

business graphics package ranges in cost from $200 to

$1000. Most programs require a pointing device like a

mouse, trackball, or digitizing tablet.

Computer Communications

The telecommunications revolution has followed close on

the heels of the information revolution. In fact the two -

information and communication - go hand in hand. Once

computers were on the scene, it was only a matter of time

before it became necessary to connect them to one another

to exchange information electronically. Today, hardly any

business or agency which uses computers can escape the

need to have its computers talk to someone else’s.

“Bulletin boards” are software systems that permit users to

post notices electronically. To respond to a notice, another

user simply identifies which notice he or she wishes to

access, and appends the record with a new message or notice.

After a time, these records are cleared to make room for

others. Many bulletin boards also offer special areas for

25
users to communicate in real-time directly through their

computers. In these applications, information is exchanged

between the sender and receiver through the host computer

with text being directed immediately to the video display

terminals of the participants.

Specialized electronic forums for fire service, law enforcement, and fire safety professionals have appeared on mainstream bulletin board and electronic information exchange

services in recent years. The most visible of these are

managed by national fire service and law enforcement

organizations. A few individuals around the country have

also setup bulletin boards. The Building and Fire Research

Laboratory (BFRL) at the National Institute of Standards

and Technology (NIST) operates a special interest bulletin

board at no cost other than a toll call to the suburban

Washington, D.C. area. The Fire Research Bulletin Board

Service (FRBBS) has been in operation since 1986, and has

around 200 periodic ‘users.’

FIRE MODELING SOFTWARE

A great deal of time over the past decade has been spent

improving techniques for predicting fire behavior in simple

compartment fires. As the result of these efforts, several

excellent programs for modeling fire behavior in single and

multiple compartment fires have become widely available.

Many of these programs are zone models. A zone model uses

the fundamental rules of conservation of mass and energy to

calculate the position and travel of the, hot gas layer in

compartment fires. In general, these models require users to

specify the size and arrangement of compartments, the

location and area of vents (windows, doors, mechanical

ventilation, and through-penetrations), and the energy release rates, i.e. heat-release-rate (HRR), for the fire(s) to be

modeled. The outputs of each model vary, but most predict

the time to certain discrete events like flashover or fatal

concentrations of specified fire gas species. Most of the

available models are programmed to operate on computers

using the DOS operating system.

The most widely recognized source of compartment or

enclosure computer fire modeling programs is the United

States is the Department of Commerce’s National Institute

of Standards and Technology, Building and Fire Research

Laboratory (NIST/BFRL) in Gaithersburg, Maryland. Some

of the models which have particular application to fire

investigation include the following:

HAZARD I - user-friendly tire hazard analysis

program

1

 FRBBS can be reached at (301) 921-6302 using most commercial communications. Your system should be setup for 8 bits, even parity, no stop bit (8-E-0).

If you require assistance, the SYSOP (Scot Deal or Charles Arnold) can be

reached at (301) 975-6891.

DETACT-T2 and DETACT-QS - predicts detector

activation

ASET - calculates available safe egress time

CCFM (version VENTS) - multi-compartment

zone fire model

TENAB - tenability model

EXITT -exit time simulation program

BREAK1 - for glass breakage predictions

FPETOOL - for fire protection engineering cal

culations

All of these models can be downloaded from the NIST/

BFRL’s Fire Research Bulletin Board Service (FRBBS) by

calling (301) 921-6302. FRBBS is menu driven and walks

the new user through a sign-on and password selection for

future access.

Many of the models listed are used to predict the outcome of

a given user-defined fire or some aspect of that fire. These

models can also provide a useful way of deconstructing or

reconstructing the events which led to a specific fire outcome. In the field of fire investigation, the results of a given

fire are already known. The difficult task of figuring out

what happened requires determiningwhat was there to begin

with and how it got the way it was found. Combining the

other tools of fire investigation with the power of fire

modeling can be a highly effective means of ensuring that

fire cause and fire development scenarios are plausible,

meaningful, and well-reasoned. Computer fire models are

good tools for helping fire investigators understand, not

determine, what happened during a given fire.

26
Chapter 6 - INFORMATION RESOURCES

A good basic library of texts, handbooks, reports, journals, and periodicals will help the fire investigator stay well-informed

about developments in the field and serve as ready references during complex investigations.

THE FIRE INVESTIGATOR’S REFERENCE LIST

The following publications are widely held to be some of the

best basic references about fire and arson investigation.

Every fire investigation agency should seriously consider

acquiring all of the latest of editions of each volume.

FIRE INVESTIGATOR’S REFERENCE LIST

ASTM Committee E-5 on Fire Standards (1990). Fire Test

Standards, 3rd ed. Philadelphia, PA: American

Society for Testing and Materials.

California District Attorney’s Association and Aetna Insurance, Arson Investigation and Prosecution.

Cole, L. S. (1985). Investigation of Motor Vehicle Fires,

2nd ed. Novato, CA: Lee Books.

Cote, A. E., ed. (1991). Fire Protection Handbook, 17th ed.

Quincy, MA: National Fire Protection Association.

DeHaan, J. D. (1990). Kirk’s Fire Investigation, 2nd ed.

Englewood Cliffs, NJ: Prentice-Hall.

Dils, J. (1990). Writing Fire and Non-fire Report Narratives. Pasadena, CA: Jan Dils.

DiNenno, P. J!, ed. (1988). SFPE Handbook of Fire

Protection Engineering, Quincy, MA: National

Fire Protection Association.

International Association of Arson Investigators (1983).

Selected Articles for Fire Investigators, 5th ed.

Louisville, KY: IAAI.

Kodak (1977). Fire and Arson Photography, Pamphlet M67. Rochester, NY: Eastman Kodak Co.

NFPA 921, Guide for Fire and Explosion Investigations

(1992). Quincy, MA: National Fire Protection

Association.

Shields, T. J. (1987). Buildings and Fire. New York:

Halsted Press.

Yereance, R. A. (1987). Electrical Fire Analysis. Springfield, IL: Charles C. Thomas.

Zulawski, D. E. and Wicklander, D. (1991). Practical

Aspects of lnterview and lnterrogation. NewYork:

Elsevier.

JOURNALS AND PERIODICALS

Keeping current in any complex field is a constant challenge. Fortunately, several excellent magazines, periodicals, and journals are available which run articles of interest

to the fire investigator. Many of these publications subject

published articles to careful editing or peer review to ensure

accuracy and integrity and many do not. The following is a

partial listing of relevant fire service and fire-related publications available in the United States:

AMERICAN FIRE JOURNAL

9072 E. Artesia Boulevard, Suite 7

Bellflower, CA 90706

BUILDING OFFICIAL AND CODE ADMINISTRATOR

BOCA International, Inc.

4051 W. Flossmoor Road,

Country Club Hills, IL 60478

BUILDING STANDARDS

International Conference of Building Officials

5360 S. Workman Mill Road

Whittier, CA 90601

CALIFORNIA FIREMAN, THE

California State Firemen’s Association, Inc.

3246 Ramos Circle

Sacramento, CA 95827

CALIFORNIA STATE FIRE MARSHAL’S NEWS

Special Services Division

7171 Bowling Drive, Suite 600

Sacramento, CA 95823

CHIEF FIRE EXECUTIVE

PTN Publishing Company

445 Broad Hollow Road, #21

Melville, NY 11747

27
DISPATCH

1325 Pennsylvania Avenue NW

Washington, DC 20004

INTERNATIONAL ASSOCIATION OF

FIREFIGHTERS MAGAZINE

1750 New York Avenue NW

Washington, DC 20006

FIRE AND ARSON INVESTIGATOR, THE

International Association of Arson lnvestigators

P.O. Box 91119

Louisville, KY 40291

INTERNATIONAL CONNECTIONS

International. Association of Fire Chiefs

4025 Fair Ridge Road

Fairfax, VA 22033

FIRE CHIEF

Communication Channels, Inc.

307 N. Michigan Avenue

Chicago, IL 60601

MINNESOTA FIRE CHIEF

3 17 Owasso Boulevard South

St. Paul, MN 55 113

FIRE CODE JOURNAL NATION’S CITIES WEEKLY

International Fire Code Institute National League of Cities

5360 S. Workman Mill Road 1301 Pennsylvania Avenue NW

Whittier, CA 90601 Washington, DC 20004

FIRE CONTROL DIGEST

3918 Prosperity Avenue, Suite 3 18

Fairfax, VA 22031

FIRE ENGINEERING

Park 80 West

Plaza Two, 7th Floor

Saddle Brook, NJ 07662

NFPA JOURNAL

National Fire Protection Association

1 Batterymarch Park

P.O. Box 9101

Quincy, MA 02269

FIREFIGHTER’S NEWS

424 S. Rehobeth Road

P.O. Box 165

Milford, DE 19963

OREGON FIRE SERVICE GATED WYE

Oregon State Fire Marshal’s Office

4760 Portland Road NE

Salem, OR 97305

FIREHOUSE

PTN Publishing Company

445 Broad Hollow Road

Melville, NY 11747

PUBLIC FIRE EDUCATION DIGEST

Oklahoma State University

2004 S. Deerborn Circle

Columbia, MO 65203

SIZE-UP

FIRE TECHNOLOGY

National Fire Protection Association

1 Batterymarch Park

P.O. Box 9101

Quincy, MA 02269

New York State Association of Fire Chiefs

1670 Columbia Turnpike

Castleton, NY 12033

IAFC ON-SCENE

International Association of Fire Chiefs

4025 Fair Ridge Road

Fairfax, VA 22033

SPEAKING OF FIRE

International Fire Service Training Association

Fire Protection Publications

Oklahoma State University

Stillwater, OK 74078

THE VOICE

INDUSTRIAL FIRE WORLD

208-C Southwest Parkway East

College Station, TX 77842

International Society of Fire Service Instructors

30 Main Street

Ashland, MA 01721

28
PROCEEDINGS

Much of the important work done at the frontier of fire

science does not appear in the better known and more

mainstream fire protection publications. Most academic

conferences and technical symposiums do, however, publish documents such as proceedings. These publications

serve as conduits for the papers presented at these meetings

and conferences. Many of these meetings convene at regular

intervals, others are far more adhoc, occurring only once or

periodically but irregularly. The annual National Arson

Forum meetings sponsored by the Insurance Committee for

Arson Control and the Worcester Polytechnic Institute

sponsored Conference on Fire Safety Design in the 21st

Century are examples of such symposiums.

ELECTRONIC INFORMATION SERVICES

Chapter 5 contains information about several electronic

information services of particular interest to fire investigators. Many of the mainstream information services give

users the ability to set up clipping files newspaper and wire

service articles about topics of interest by using keywords to

search the text of each story as it appears on the network.

This can be a particularly efficient way of gaining up-to-date

information about emerging trends in the field or significant

events around the nation or the world.

Specialized Electronic Reference Sources

Many libraries have begun providing access to specialized

electronic reference sources, occasionally charging a small

fee to cover their on-line charges. Some of the more

sophisticated services give users up-to-date access to legal

decisions, law review articles, scientific and technical journals, social science abstracts, medical journals, patent and

trademark files, and dissertation abstracts. In fact, most

major reference sources in print have begun to appear in

electronic versions.

Fire Service Bulletin Boards

In recent years, fire-oriented bulletin board services have

begun to emerge. The lnternational Association of Fire

Chiefs and the National Volunteer Fire Council operate two

such services. The IAFC information service, ICHIEFS,

operates as a special interest forum on another on-line

service called ConnectTM . FireWatch, the NVFC forum,

operates as stand-alone system from a computer located in

Colorado. As computer technology becomes increasingly

ubiquitous one can only expect the number of fire-related

electronic information services to expand as well. Contacts

are as follows:

ICHIEFS

Ken Westlund

National Volunteer Fire Council

1422 East 110th Place

Northglen, Colorado 80233

(303) 452-9992

FireWatch

Ann Swing

lnternational Association of Fire Chiefs

4025 Fair Ridge Road

Fairfax, Virginia 22033

(703) 273-0911

UNITED STATES FIRE

ADMINISTRATION

PUBLICATIONS

The following United States Fire Administration publications provide information useful to fire and arson investigators. A catalog containing all United States Fire Administration publications, titled Resources on Fire (FA-102), is

available by contacting the United States Fire Administration, 16825 South Seton Avenue, Emmitsburg, Maryland

21727, (301) 447-1000.

Fire and Arson Investigator’s Field Index Directory (FA-91) -

This publication serves as a compendium of expert contacts

in federal agencies, government and private research laboratories, codes and standards organizations, trade associations, product manufacturers and distributors, insurance

companies and organizations, law enforcement agencies

and organizations, and other valuable contacts for technical

information and resources for fire and arson investigators

handling complex cases.

Arson Resource Directory (FA-74) - This directory provides a comprehensive listing and explanation of the roles of

the various organizations and agencies across the nation

involved in the fight to control arson. It includes names and

contact information for county and metropolitan fire and

arson investigation units, state fire marshals offices, state

training organizations, National Fire Incident Reporting

system coordinators, federal agencies, and other organizations such as the Federal Arson Task Force and International

Association of Arson Investigators, and other fire service

and insurance organizations.

Arson Control Directory - This directory is produced

annually through a cooperative agreement between the

United States Fire Administration, the lnsurance Committee

for Arson Control, National Association of State Fire Marshals, and the lnternational Association of Arson Investigators working through the National Arson Forum. It details

29
the people, groups, and organizations working to reduce the

incidence of arson in the United States.

Public Fire Education Today: Fire Service Programs

Across America (FA-98) - This publication identifies and

describes successful public fire education programs in all 50

states and the District of Columbia. Several good examples

of anti-arson and juvenile firesetter programs are included in

the cases presented.

Rural Arson Control (FA-87) - This study report outlines

the difficulties confronting rural communities in the fight

against arson and recommends solutions to help these communities win the war against incendiarism.

Establishing an Arson Strike Force (FA-88) - This report

describes the Arson Strike Force concept for investigating

fires and prosecuting the crime of arson. This model has

proven to be one of the most successful programs for

combatting arson. The report outlines how to establish and

administer and arson strike force in your community.

Arson Prosecution: Issues and strategies (FA-78) - This

report describes the recommended methods for successfully

developing and prosecuting arson cases. It details the roles

of prosecutors, eyewitnesses, expert witnesses, investigators, and different types of evidence and emphasizes how to

present each element of the prosecution to build a credible

and convincing case.

Preadolescent Firesetter Handbook (3 volumes) (FA-80,

FA-82 and FA-83) - These manuals present an overview

of juvenile firesetter behavior and outline successful counseling and intervention programs and strategies for three

different age groups, 0-7, 7-13, and 14-18. Sample interview

and evaluation forms are provided to illustrate key concepts.

And contacts are provided for existing programs in communities nationwide.

Special Report - Arson in America: A Profile of 1989

NFIRS - This report examines the scope of the incendiary

fire problem in America through an analysis of National Fire

incident Reporting System (NFIRS) data for calendar year

1989. NFIRS data is based on reports collected from over

10,000 fire departments in 40 states, and 27 metropolitan

areas which cooperate in the National Fire Incident Reporting System.

A View of Management in Fire Investigation Units (FA93) - Particular management practices from several local

fire investigation units are highlighted. Factors affecting the

current state of fire investigation are described, including

the trend away from joint police and fire investigation teams,

the impact of drug wars on the quantity and danger of

investigations, the need for management training for investigation managers, and inadequate data collection and application.

In addition to these publications, the United States Fire

Administration maintains an Arson Resource Center in the

National Emergency Training Center Learning Resources

Center. Expert technical reference librarians are on-call to

assist local fire investigations in finding information and

specific fire and arson investigation topics. The Arson

Resource Center can be reached by calling toll-free (800)

638-1821.

30
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Walton, W. D. and Budnick, E. K. (I 991). “Deterministic

Fire Models,” in Fire Protection Handbook, 17th ed.,

Cote, A. E., ed. Quincy, MA: National Fire Protection

Association.

Watts, J. M., Jr. (1991). “Microcomputer Applications in

Fire Protection,” in Fire Protection Handbook, 17th ed.,

Cote, A. E., ed. Quincy, MA: National Fire Protection

Association.

33
APPENDIX A

FIRE INVESTIGATION TOOLS AND EQUIPMENT LISTS

HAND TOOLS Screwdriver(s)

Bit driver with assorted bits

Chisels Phillips head

Cold chisel(s) Straight blade

Wood chisel(s) Screws, nails, tacks, staples

Crowbar/prybar Wrenches

Cutter(s), cutting tools Adjustable

Bolt cutters Open-end or box

Carpet cutters Pipe

Pipe cutter

Pocket knife EVIDENCE TOOLS AND EQUIPMENT

Razor blades

Tin snips Brush(es)

Utility knife

Drill with wood and metal bits

Containers, packaging materials

Cardboard boxes, assorted sizes

Electrician’s tools

Circuit continuity tester

Document protector(s)

Envelopes, kraft paper or tyvekTM, assorted sizes

Electrical tape Evidence tape (tamper indicating)

Fuse puller Glass jars w/ screw-top lids, assorted sizes

Ground fault/phase tester Glass vials w/ screw-top lids

Volt/Ohm/Amp meter Kraft paper

Wire cutters Masking tape

Wire gauge Wire stripper Paper bags

Hammers Plastic (polyester, nylon, or KapakTM) bags,

Ballpeen heavy duty (+3-mil)

Claw Steel paint cans w/ friction lids, assorted sizes

Hand axe/hatchet String

Hand trowel Transparent or cellophane tape

Level (torpedo and bar) Vermiculite

Magnet Drawing equipment

Magnetic compass

Measuring tools

Compass (drafting)

Drafting templates, architectural

Folding rule Pens, pencils

Measuring wheel Protractor

Ruler (12-in, 14-in, 18-in) Scale, architectural

Tape (25-ft, 50-ft, 100-ft) Scale, engineering

Paint brush(es) Straight edge

Pliers Sketch pads, quadrille ruled

Lineman’s Fingerprint kit

Needle-nose Latex rubber gloves

Sidecutting Magnifying glass

Slip-lock Marking equipment

Vise-GripTM

Evidence tags/forms

Plumb bob Marking pens, indelible ink

Putty knife/scraper(s) Scribe, etching tool

Saws Measuring equipment

Crosscut Magnetic compass

Hack Scale or balance

Keyhole Range finder

Scroll Meters

34
Barometer

Combustible gas/vapor detector

Thermometer, dry bulb

Thermometer, wet bulb

Velometer

pH

Notebooks

Recording equipment, sound

Blank cassette tapes

Tape recorder

Sample collection equipment

Activated charcoal

Blotter strips

Cotton-tipped swabs

Cotton baby diapers, clean, unused

Dental tools

Disposable sterile pipets with suction bulbs

Dust pans

Eye dropper

Forceps

Scalpel

Sifting screens or sieve

Syringes

Tongs

Tweezers

UV (black) light

PHOTOGRAPHIC AND VIDEO

EQUIPMENT

Batteries, spare

Camera

Flash

Camera

35 mm automatic

35-mm SLR

Instant

Film, spare

Flash attachment

Instant camera macro attachment

Lenses

70-200 mm zoom

28-70 mm zoom

50 mm

Meter

Flash

LightMotor winder

Photographic background

Photographic flags/markers

Photographic logs

Photographic ruler

Protective carrying cases

Tripod

Videotape boom microphone

Videotape lighting attachment

Videocassettes, blank, spare

PERSONAL PROTECTIVE EQUIPMENT

Ballistic vest

Brush firefighting coat

Brush firefighting pants

Boots, steel toe/shank safety

Chemical splash protective coveralls

Coveralls

Dust mask(s)

Filter mask respirator

Firefighter’s boots

Firefighter’s gloves

Firefighter’s turnout coat

Firefighter’s turnout pants

Goggles/safety glasses

Hardhat

Law enforcement equipment

Handcuffs/case

Handgun, holster, ammunition

Gun cleaning kit

NomexTM/PBI hood

Respirator filters, organic vapor/acid gas/HEPA

Self-contained breathing apparatus

Spare SCBA bottle(s)

Structural firefighter’s helmet

Suspenders

Work gloves

COMMUNICATION EQUIPMENT

Cellular telephone

Facsimile machine

Cellular

Office

Portable radio

Pager

Radio

Telephone

Portable computer w/ modem

Public address system

VEHICLE EQUIPMENT

AC/DC charger

First aid kit

Flood lights

Fusees/light sticks

Jumper cables

Mobile Radio

Portable fire extinguisher

Public address system

Reflective markers

Siren

35
Spot light(s)

Warning lights

MISCELLANEOUS TOOLS AND EQUIPMENT

Barricade tape

Broom(s)

Buckets

Claw tool

Cleaning rags

Entrenching tool

Extension cords

Flashlights

Hand cleaner

Hand lanterns

Hydrant wrench

Ladder, extension

Ladder, step

Light stands

Pick

Portable generator

Portable lights

Rope

Shovel, chisel point

Shovel, scoop

Shovel, square head

Spade

Squeegee

Tarps/salvage covers

36
APPENDIX B

GLOSSARY OF FORENSIC SCIENCE TERMS

Source: International Association of Arson Investigators Forensic Science Committee (Dec. 1989), “Glossary of Terms

Related to Chemical and Instrumental Analysis of Fire Debris,” Fire and Arson Investigator, Vol. 40, No. 2, (pp. 25-34).

-AAbsorption: 1) A mechanical phenomenon wherein one

substance penetrates into the inner structure of another, as in

absorbent cotton or a sponge. 2) An optical phenomenon

wherein atoms or molecules block or attenuate the transmission of a beam of electromagnetic radiation.

Accelerant: Any material used to initiate or promote the

spread of a fire. The most common accelerants are flammable or combustible liquids. Whether a substance is an

accelerant depends on its chemical structure, but on its use.

Acetone: The simplest ketone. A highly flammable, water

soluble solvent. Flash point of 0° F. Explosive limits of 2.6%

to 12.8%.

Adsorption: The adherence of atoms, ions, or molecules of

a gas or liquid to the surface of another substance. Finely

divided or microporous materials having a large active

surface area, activated carbon, activated alumina and silica

gel.

Alcohol: An organic compound having a hydroxyl (-OH)

group attached. The lower molecular weight alcohols,

methanol (CH3OH), ethanol (C2H5OH), and propanol

(C3H7OH), are water soluble.

Aliphatic: One of the main groups of hydrocarbons characterized by the straight or branched chain arrangement of

constituent atoms. Aliphatic hydrocarbons belong to three

subgroups: (1) alkanes or paraffins, all of which are saturated and comparatively unreactive, (2) the alkenes or

alkadienes which are unsaturated (containing double [C=C]

bonds) and more reactive, and (3) alkynes, such as acetylene

(which contain a triple [C=C] bond).

Alkane: An aliphatic hydrocarbon having the chemical

formula CnH2n+2. A normal alkane, or n-alkane is one

which does not have a branched carbon backbone. An

isoalkane has a branched, rather than a straight chain, carbon

backbone. Alkanes are also known as paraffins. The

simplest alkanes are named as follows:

CH4 - methane C8H18 - octane

C6H14 - hexane . C4H10 - butane

C2H6 - ethane C9H20 - nonane

C7H16 - heptane C5H12 - pentane

C3H8 - propane C10H22 - decane

Alkene: A straight chain, unsaturated compound of the

olefin series which has the generic formula CnH2n, having

at least one double [C=C] bond. (See Aliphatic).

Alkyl Group: A functional group having the formula

CnH2n+l which may be attached to certain elements such

as lead, silicon, or to other organic chemicals.

Alkyne: An unsaturated aliphatic hydrocarbon characterized by the presence of a triple [C=C] bond. The generic

formula for an alkyne is CnH2n-2. The most important

member of this group is acetylene, HCCH, the first member

of the series.

Alloy: A solid or liquid mixture of two or more metals, or

of one or more metals with certain nonmetallic elements, as

in brass, bronze, or carbon steel.

Ambient: Pre-existing or normal environment.

Aromatic: An organic compound having as part of its

structure a benzene ring. (See Benzene). The term “aromatic” as used in the fragrance industry is used to describe

essential oils, which are not necessarily aromatic in the

chemical sense.

Arson: The crime of intentionally setting fire to a building

or other property. This is a legal definition which may vary

depending on the laws of a specific state.

Atom: The smallest unit of an element which still retains the

chemical characteristics of that element. An atom is made

up of protons and neutrons in a nucleus surrounded by

electrons. A molecule of water (H2O) consists of two atoms

of hydrogen and one atom of oxygen.

Atomic Absorption: An analytical technique, used to

determine the elemental composition and the concentration

of many metals and other inorganic elements. The material

being analyzed, generally in solution, is atomized, or broken

up into individual atoms, usually by the action of extreme

heat in a flame or small furnace. The ability of the atomized

material to absorb characteristic wavelengths of visible or

ultraviolet light is then measured using a spectrophotometer.

Atomize: 1) To break into discrete atoms, usually by the

application of extreme heat, as in atomic absorption. 2) To

break a liquid into tiny droplets, as occurs in fuel injected

engines or in the production of aerosol sprays.

37
Attenuation: An adjustment of the signal amplifier response which results in the reduction of the electronic signal.

Azeotrope: A mixture of two or more compounds which has

a constant boiling point. The composition of the vapor above

the azeotropic mixture has the same relative concentrations

of compounds as does the boiling liquid. Azeotropic mixtures cannot be separated by fractional distillation.

-BBenzene: A hexagonal organic molecule having a carbon

atom at each point of the hexagon, and a hydrogen atom

attached to each carbon atom. Molecules which contain a

benzene ring are known as aromatic. Benzene boils at 80° C,

and has a flash point of 12° F(-11° C). The explosive limits

are 1.5% to 8% by volume in air.

BTU: British Thermal Unit. The amount of heat energy

required to raise the temperature of one pound of water one

degree Fahrenheit. This the accepted standard for the

comparison of heating values of different fuels. One BTU

equals 252 calories.

Burning: Normal combustion in which the oxidant is

molecular oxygen.

Burning Rate: The rate at which combustion proceeds

across a fuel. A specialized use of this term describes the rate

at which the surface of a pool of burning liquid recedes. For

gasoline, this rate is reported to be approximately 1/4 inch

per minute.

Butane: A fuel gas having the formula C2H10. A constituent

of LP gas. One pound of liquid butane produces 6.4 cubic

feet of gas. One gallon of liquid butane weighs 4.87 pounds

and produces 31 cubic feet of gas. One cubic foot of butane

gas produces 3266 BTU’s.

-CCalorie: The amount of energy required to raise the

temperature of one gram of water one degree Centigrade.

One calorie equals 0.004 BTU’s One BTU equals 252

calories.

Capillary: A narrow boreglass tube. Capillary column gas

chromatography employs glass tubes having an inside diameter of approximately .2 to .5 millimeters and a length of 3

to 300 meters. The walls of a capillary column are coated

with an adsorbent or adsorbents medium (a liquid phase in

which the sample dissolves).

Carbon: The element upon which all organic molecules are

based. Carbon has an atomic weight of 12.00, and occurs

elementally in these forms: diamond, graphite, and amorphous carbon such as coal or carbon black.

Carbon Dioxide: A molecule consisting of one atom of

carbon and two atoms of oxygen which is a major combustion product of the burning of organic materials. Carbon

dioxide (CO,) is the result of complete combustion of

carbon. In the gaseous form, CO, is used as a fire extin;

guisher. In the solid form, CO, is known as dry ice. CO, is

heavier than air, with a vapor density of 1.53 (air=1.00).

Carbon Disulfide: A highly flammable nonpetroleum

solvent used extensively for gas chromatography because of

its relatively low signal generated in a flame ionization

detector. Carbon disulfide has the formula CS2. Reagent

grade CS2 has an odor similar to rotten broccoli, and can be

ignited by contact with boiling water. It burns with a blue

flame, producing CO, and SO, (sulfur dioxide). The explosive limits of CS2

 are 1 to 50%. CS2 has a flash point of -22° F.

Carbon Monoxide: A gaseous molecule having the formula CO, which is the product of incomplete combustion of

organic materials. Carbon monoxide has an affinity for

hemoglobin approximately 200 times stronger than oxygen’s

and is highly poisonous. CO is a flammable gas which burns

with a blue flame, and has explosive limits of 12% to 75%.

Carbon monoxide has approximately the same vapor density

as air, 0.97 (air=1.00).

Carbon Tetrachloride: A nonflammable liquid having the

formula CC,,, formerly used as a fire extinguisher, and still

used as a solvent and cleaning agent. Carbon Tetrachloride

boils at 77° C.

Chain Reaction: A self-propagating chemical reaction in

which activation of one molecule leads successfully to

activation of many others. Most, perhaps all, combustion

reactions are of this kind.

Chemical Change: Rearrangement of the atoms, ions or

radicals of one or more substances, resulting in the formation

of new substances, often having entirely different properties.. Also known as a chemical reaction.

Chemistry: A basic science concerned with (1) the structure and behavior of atoms (elements); (2) the composition

and properties of compounds; (3) the reactions that occur

between substances, and the resultant energy exchange and

(4) the laws that unite these phenomena into a comprehensive system.

Chromatography: A chemical separation procedure which

separates compounds according to their affinity for an

adsorbent or absorbent material. Chromatography includes

Thin Layer Chromatography (TLC), Liquid Chromatography (LC), Gas Chromatography (GC) (sometimes called

Gas Liquid Chromatography or GLC) and High Performance Liquid Chromatography or High Pressure Liquid

Chromatography (HPLC).

38
Comparison Sample: 1) A sample of material collected

from a fire scene which is, to the best of the investigators

knowledge, identical in every respect to a sample suspected

of containing accelerant, but which does not contain accelerant. 2) A sample of suspected accelerant submitted to the

purpose of comparing with any accelerant separated from a

debris sample. (See Control Sample).

Combustible Liquid: A liquid which is capable of forming

a flammable vapor/air mixture. All flammable liquids are

combustible. Whether a liquid is combustible or flammable

depends on its flash point and on the agency definition relied

upon. The Coast Guard classifies all liquids with a flash

point below 80° F as flammable. The NFPA uses 100° F.

Combustion: An exothermic chain reaction between oxidizing and reducing agents, or between oxygen and fuel.

Combustion may occur with any organic compound, or with

certain combustible elements such as hydrogen, sulfur, and

finely divided metals.

Component: 1) One of the elements or compounds present

in a system such as a phase, a mixture, a solution, or a

suspension in which it may or may not be uniformly dispersed. 2) A compound or a group of unresolved compounds

represented by a peak on a chromatogram.

Compound: A chemical combination of two or more

elements, or two or more different atoms arranged in the

same proportions and in the same structure throughout the

substance. A compound is different from a mixture in that

the components of a mixture are not chemically bonded

together. For example, a flash may contain two volumes of

hydrogen (H2) gas and one volume of oxygen (O2) gas. A

different flash might contain only water vapor (H2O). In the

first case, two gases are mixed. In the second case only one

gas is present.

Concentration: The amount of substance in a stated unit of

a mixture or solution. Common methods of stating concentration are per cent by weight, per cent by volume, or weight

per unit volume. (e.g. parts per million, billion, etc.)

Conduction: Passage of heat from one material to another

by direct contact.

Conductivity: The ability of a material to transfer energy

from one place to another. Thermal conductivity describes

a substance’s ability to transmit heat. Electrical conductivity describes a substance’s ability to transmit electrical

current. Conductivity is the opposite of resistivity.

Control Sample: A sample of material which is known to

be identical to a sample suspected of containing accelerant

in every regard, except that the control sample does not

contain accelerant. A known blank sample. In practical

terms, control samples do not exist in the setting of a fire

scene because 1) exact conditions during the fire cannot be

duplicated from location to location, and 2) exact conditions

of the substrate, i.e., carpet, etc., are not known. Carpet in

Room A may have had various items spilled on it during use.

Carpet B (ten feet away) may be brand new. (See Comparison Sample).

Convection: Transfer of heat by the movement of molecules in a gas or liquid, with the less defense fluid rising.

The majority of heat transfer in a fire is by convection.

Corrosion: The degradation of metals or alloys due to

reaction with their environment. It is accelerated by acids,

bases or heat.

Cracking: A refining process involving decomposition and

molecular recombination of organic compounds, especially

hydrocarbons obtained by distillation of petroleum, by

means of heat, to form molecules suitable for various used

such as motor fuels, solvents or plastics. Cracking takes

place in the absence of oxygen,.

-DDeflagration: Vigorous burning with subsonic flame propagation. (See Detonation)

Desorption: The process of removing an adsorbed material

from the solid on which it is adsorbed. (See Adsorption)

Detonation: An exothermic chemical reaction which propagates through reactive material at supersonic speed.

Diesel Fuel: Diesel Fuel consists mostly of hydrocarbons

ranging from C10 through C24. The composition of diesel fuel

may vary with changes in latitude or changes in season. This

variability is provided by the refinery to control the volatility

of the product. In order to be identified as diesel fuel, a

sample extract must exhibit a homologous series of five or

more consecutive normal alkanes ranging from C12 through

C22. Diesel fuel has a flash point of 120 to 160° F and

explosive limits of 0.7% to 5%. Many states specify a

minimum flash point for diesel fuel.

Distillation: A separation process in which a liquid is

converted to a vapor, and the vapor is then condensed back

to a liquid. The usual purpose of distillation is separation of

the compounds of a mixture. Steam distillation separates all

water insoluble liquids from solids and water soluble compounds in a mixture.

Drying Oil: An organic liquid which, when applied as a thin

film, readily absorbs oxygen from the air and polymerizes to

form a tough elastic film. Linseed, tung, soybean and castor

oils are drying oils. ‘Under certain conditions, usually

involving large surface areas and insulation, such as a pile

of rags soaked with drying oils, spontaneous heating may occur.

39
-EElectron: A negatively charged subatomic particle which

circles the nucleus of the atom in a cloud. Most chemical

reactions involve the making and breaking of bonds held

together by the sharing of electrons.

Evaporation Rate: A measure of the quantity of a liquid

converted to vapor in a unit of time. Among single

component liquids, the rate varies directly with the surface

area, the temperature and the vapor pressure, and inversely

with the latent heat of vaporization of the liquid.

Electron Capture Detector (ECD): A type of gas chromatographic detector which is sensitive to halogenated

hydrocarbons and other molecules capable of easily gaining

an electron. Electron capture is not generally used for

hydrocarbon detection.

Exothermic Reaction: A chemical reaction which evolves

heat. Combustion reactions are exothermic.

Explosion: The sudden conversion of chemical energy into

kinetic energy with the release of heat, light and mechanical

shock.

Element: One of 106 presently known kinds of substances

that comprise all matter at and above the atomic level.

Elution: The process of removing adsorbed materials from

the surface of an adsorbent such as activated charcoal. The

solvent in this process is called the eluant.

Explosive Limit: Flammability limit. The highest or

lowest concentration of a flammable gas or vapor in air that

will explode or burn readily when ignited. This limit is

usually expressed as a volume percent of gas or vapor in air.

Emission Spectroscopy: The study of the composition of

substances and identification of elements by observation of

the wave lengths of radiation emitted by the substance as it

returns to a normal state after excitation by an external

source. Generally used for elemental analysis.

Explosive Range: Flammability range. The set of all

concentrations between the upper and lower, explosive

limits of a particular gas or vapor.

Emulsion: A stable mixture of two or more immiscible

liquids in suspension.

Extraction: A chemical procedure for removing one type

of material from another. Extraction is generally carried out

by immersing a solid in a liquid, or by shaking two immiscible liquids together, resulting in the transfer of a dissolved

substance from one liquid to the other. Solvent extraction

is one of the primary methods of sample preparation in arson

debris analysis.

Endothermic Reaction: A chemical reaction which absorbs heat. -FEthane: A simple alkane having the formula C2H6

. A minor

component of natural gas. Its explosive range is 3% to

12.5%. Ethane has approximately the same vapor density as

air.

Fire: The light and heat manifested by the rapid oxidation

of combustible materials. A flame may be manifested but

is not required.

Ethanol: Ethyl alcohol. Grain alcohol. Flammable, water

soluble alcohol. Flash point of 55° F. Explosive limits of

3.3% to 19%.

Ether: Diethyl ether, ethyl ether. A highly flammable

solvent which can form explosive peroxides when exposed

to air. Flash point of -49F. Explosive range of 1.85% to 48%.

Fire Point: The temperature, generally a few degrees above

the flash point, at which burning is self-sustaining after

removal of an ignition source.

Fire Tetrahedron: Fuel, heat, oxygen and a chemical chain

reaction.

Fire Triangle: Fuel, heat and oxygen.

Ethylbenzene: A component of gasoline, but also a major Flame: A rapid gas phase combustion process characterbreakdown product or pyrolysis product given off when ized by a self-propagation. 

certain polymers are heated.

Eutectic: The lowest melting point of an alloy or solution

of two or more substances (usually metals) that is obtainable

by varying the percentage of the components. Eutectic

melting sometimes occurs when molten aluminum or molten zinc comes in contact with solid steel or copper.

Evaporation: Conversion of a liquid to the vapor state. Set

Flame Ionization Detector (FID): A nearly universal gas

chromatographic detector., It responds to almost all organic

compounds. An FID does not respond to nitrogen, hydrogen, helium, oxygen, carbon monoxide or water. This

detector ionizes compounds as they reach the end of the

chromatographic column by burning them in an air/hydrogen flame. As the compounds pass through the flame, the

conductivity of the flame changes, generating a signal. This

also Vaporization.

40

is the most commonly used detector in arson debris analysis.
Flame Propagation: Travel of a flame through a combustible gas/air or vapor/air mixture.

Flammability Limit: (See Explosive Limit)

Flammability Range: (See Explosive Range)

Flammable Liquid: A combustible liquid that has a flash

point below 80°F according to the Coast Guard, 100°F

according to NFPA. Liquids having a vapor pressure over

40 pounds per square inch at 100°F are classified as flammable gases. Flammable liquids are a special group of

combustible liquids.

Flammable Vapor: A vapor/air mixture of any concentration within the flammability range of that vapor.

Flash Fire: A fire that spreads with unusual speed, as one

that races over flammable liquids or through combustible

gases. The temperature at which a pool of liquid will

generate sufficient vapors to form an ignitable vapor/air

mixture. The temperature at which a liquid will produce its

lower explosive limit in air. Flash point describes one of

several very specific laboratory tests. Frequently, materials

can be made to burn below their flash point if increased

surface area or mechanical activity raises the concentration

of vapor in air above the lower explosive limit.

Fractionation: The separation of one group of compounds

in a mixture from another, generally by distillation.

Fuel Oil: A heavy petroleum distillate ranging from #1

(kerosene or range oil), #2 (diesel fuel), up through #6

(heavy bunker fuels). To be identified as fuel oil, a sample

must exhibit a homologous series of normal alkanes ranging

from C9 upward.

-GGas Chromatography (also known as Gas Liquid Chromatography):. The separation of organic liquids or gases

into discrete components or compounds seen as peaks on a

chromatogram. Separation is done in a column which is

enclosed in an oven held at a specific temperature, or

programmed to change temperature at a reproducible rate.

The column separates the compounds according to. their

affinity for the material inside the column (stationary phase).

Columns can be either packed or capillary. Packed columns

employ a powder) substance which may be coated with a

nonvolatile liquid phase. A capillary column is a glass or

quartz tube coated with a nonvolatile liquid. Gas Chromatography (GC) is the accepted method for identification of

hydrocarbon mixtures normally used as accelerants, and

must be performed in order to have a valid identification of

petroleum distillates.

Gasoline: A mixture of more than 200 volatile hydrocarbons in the range of C4

 to C12, suitable for use in a spark

ignited internal combustion engine. Regular automotive

gasoline has a flash point of -40°F.

-HHeadspace Concentration: A technique for concentrating

all or most of the flammable or combustible liquid vapors in

a sample on to a tube of charcoal, a wire coated with charcoal,

a charcoal coated polymer, or some other adsorbing material

which will later be desorbed in order to analyze the concentrated vapors. This is a primary form of sample preparation

in arson debris analysis. This is also known as adsorption/

elution, vapor concentration, or total headspace.

Heat: A mode of energy associated with and proportional

to molecular motion that may be transferred from one body

to another by conduction, convection or radiation.

Heptane: An alkane having the formula C7H16, flash point

of 25°F and explosive limits of 1.2% to 6.7%.

Hexane: An alkane having the formula C6H14. Flash point

of -9°F. Explosive limits of 1.2% to 7.5%.

Homologous Series: A series of similar organic compounds, differing only in that the next higher member of the

series has an additional CH2 group (one carbon atom and two

hydrogen atoms) in its molecular structure. Fuel oils are

characterized by the presence of an identifiable homologous

series of normal alkanes.

Hydrocarbon: An organic compound containing only

carbon and hydrogen.

Hydrogen: The simplest element. Atomic Number 1.

Hydrogen gas has a specific gravity of 0.0694 (air = l), so

it is much lighter than air. Hydrogen is highly flammable,

forming water upon combustion. Explosive limits are 4% to

75%.

-IIgnition: The means by which burning is started.

Ignition Temperature: The minimum temperature to

which a fuel must be heated in order to initiate or cause selfsustained combustion independent of another heat source.

Immiscible: Describes substances of the same phase or state

of matter (usually liquids) that cannot be uniformly mixed

or blended.

Incendiaries: Substances or mixtures of substances consisting of a fuel and an oxidizer used to initiate a fire.

41
Incendiary Fire: Fire set by human hands.

Incidental Accelerants: Flammable or combustible liquids

which are usual and incidental to an area where they are

detected. Gasoline is incidental to an area where gasoline

powered appliances are kept. Kerosene is incidental to an

area where a kerosene heater is kept. Flammable liquids

may also comprise a part of a product such as insecticide,

furniture polish, or paint. Additionally, certain asphaltcontaining building materials may yield detectable quantities of fuel oil components.

Infrared Spectrophotometry (IR): An analytical technique which utilizes an instrument which passes infrared

radiation through a sample or which bounces infrared radiation off the surface of a sample. A very sensitive heat

detecting device measures the amount of infrared radiation

absorbed as the wavelength of the radiation reaching the

detector is changed. IR can give useful information about

the type of compounds present in a sample, but it is not

capable of precisely identifying a complex mixture. Infrared is very useful in identifying single solvent acelerants.

Intumescent Char: In plastics, the swelling and charring

which results in a higher ignition point. Used in the

preparation of flame retardant materials.

Ion: An atom, molecule or radical that has lost or gained one

or more electrons, thus acquiring the electric charge. Positively charged ions are cations; negatively charged ions are

anions.

Isomer: One or two or more forms of a chemical compound

which have the same number and type of each atom, but a

different arrangement of atoms.

Isoparaffins: A mixture of branched alkanes usually available as a narrow “cut” of a distillation. Exxon manufactures

a group of products known as “isopars” ranging from Isopar

A through Isopar J. These solvent mixtures have a variety

of uses. Gulf Oil manufactures a similar series of solvents,

the most commonly available of which is Gulf Lite Charcoal

Starter Fluid which is roughly equivalent to Exxon’s Isopar G.

Isothermal: A type of gas chromatographic analysis where in

the column is maintained at a uniform temperature throughout the analysis. (See Programming).

-KKerosene (#1 Fuel Oil): Flash point generally between 100

and 150 degrees F. Explosive limits of 0.7% to 5.0%.

Kerosene consists mostly of C9 through C17 hydrocarbons. In

order to be identified as kerosene, a sample extract must

exhibit a homologous series five consecutive normal alkanes between C9

 and C17. Kerosene is the most common

“identical: accelerant, as it is used in numerous household

products ranging from charcoal lighter fluid to lamp oil to

paint thinner to insecticide carriers. It is also used as jet fuel.

K-l kerosene has a low sulfur content required for use in

portable space heaters.

Ketone: A type of organic compound having a carbonyl

functional group (C=O) attached to two alki groups. Acetone is the simplest example of a ketone.

-MMagnesium: A silvery metal used in some metal incendiaries. The dust is highly explosive. Ignition point of 650°F.

Mass Spectrometry: A method of chemical analysis which

vaporizes, then ionizes the substance to be analyzed, and

then accelerates the ions through a magnetic field to separate

the ions by molecular weight. Mass spectrometry can result

in the exact identification of an unknown compound, and is

a very powerful analytical technique, especially when combined with chromatography.

Meta-ethyltoluene (m-ethyltoluene): A component of

gasoline.

Matrix: Substrate. The material from which a substance of

interest is removed for analysis.

Methane: The simplest hydrocarbon and the first member

of the paraffin (alkane) series; having a formula CH4.

Methane is the major constituent of natural gas. Methane has

a heating value of 1009 BTU/cubic foot. Its explosive limits

are 5% to 15%.

Methanol: Methyl alcohol. Wood alcohol. The simplest

alcohol. Methanol is water soluble and has a flash point of

54°F and explosive limits of 6% to 36.5%.

Methyl Silicone: A nonvolatile oily liquid used in gas

chromatography to separate nonpolar compounds. Methyl

silicone columns typically separate compoundsaccording to

their boiling point.

Methylstyrene: A common polymer pyrolysis product.

Mineral Spirits:’ A medium petroleum distillate ranging

from C8 to C12. The flash point of mineral spirits, sometimes

known as mineral turps, is commonly used as a solvent in

insecticides and certain other household products. Many

charcoal lighter fluids are composed almost entirely, of

mineral spirits.

Molecular Weight: The sum of the atomic weights of all

of the atoms within a molecule. Generally, molecules of the

same type have higher boiling points if the molecular weight

is higher.

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Molecule: The smallest particle into which a substance can

be divided without changing its chemical properties. A

molecule of an element consists of one atom, or two or more

atoms that are alike. A molecule of a compound consists of

two or more different atoms.

Monomer: The simplest unit of a polymer. Ethylene is the

smallest unit of polyethylene. Styrene is the smallest unit of

polystyrene.

-NNaphtha: An ambiguous term which may mean high flash

naphtha (mineral spirits), or low flash naphtha (petroleum

ether, low boiling ligroin) or something altogether different.

Flash point and explosive limits vary. The term naphtha is

so ambiguous that it should not be used.

Natural Gas: A mixture of low-molecular weight hydrocarbons obtained in petroleum bearing regions throughout the

world. Natural gas consists of approximately 85% methane,

10% ethane and the balance propanes, butanes and nitrogen.

Since it is nearly odorless, an odorizing agent is added to

most natural gas prior to final sale.

Nebulize: To form a mist of fine droplets from a liquid. To

atomize.

Nitrogen: A gaseous element which makes up approximately 80% of earth’s atmosphere. Nitrogen is relatively

inert and does not support either combustion or life. Nitrogen is usually found in the molecular N2

 form.

-OOctane: 1) An alkane having the formula C8H18. Flash point

of 56°F. Explosive limits of 1% to 3.2%. 2) A measure of

the resistance of a sample of gasoline to premature ignition

(knocking). 100 octane fuel has the knocking resistance of

100% iso-octane (w,2,4-trimethyl pentane). Zero octane

fuel has the knocking resistance of n-heptane. 89 octane fuel

has the knocking resistance of a mixture of 89% iso-octane

and 11% n-heptane.

Olefin: An alkene. An organic compound similar to an

alkane, but containing at least one double bond. Olefins

having the formula CnH2n. The simplest olefin is ethylene,

C2H4.

Organic Chemistry: The study of the carbon atom and the

compounds it forms, mainly with the 20 lightest elements,

especially hydrogen, oxygen and nitrogen. Some 3 million

organic compounds have been identified and named.

Oxidation: Originally, oxidation meant a chemical reaction in which oxygen combines with another substance. The

usage of the word has been broadened to include any reaction

in which electrons are transferred. The substance which

gains electrons is the oxidizing agent.

Oxygen: A gaseous element which makes up approximately 20% of the earth’s atmosphere. It is usually found in

the molecular O2 form. Oxygen is the most abundant

element on earth.

-PPentane: An alkane having the formula C5H12, flash point

of -40°F, and explosive limits of 1.4% to 8%. Pentane is

frequently used to extract flammable or combustible liquid

residues from debris samples.

Petroleum Distillates: By-products of the refining of crude

oil. Low boiling or light petroleum distillates (LPD) are

highly volatile mixtures of hydrocarbons. These mixtures

are sometimes called ligroin, petroleum, ether, or naphtha.

LPDs are used as cigarette lighter fluid, as copier fluid, and

as solvents. Medium boiling petroleum distillates (MPD)

are sometimes known as mineral spirits, and are used as

charcoal starters, as paint thinners, as solvents for insecticides and other products, and as lamp oils. High Boiling or

Heavy petroleum distillates (HPD) are combustible liquids

such as kerosene and diesel fuel.

pH: A number used to represent the acidity or alkalinity of

an aqueous solution. pH7 is neutral. Acids have a pH below

7, the lower the pH, the more acidic the solution. Bases have

a pH above 7. The higher the pH, the more basic or alkaline

the solution.

Photoionization Detector (PID): A type of detector used

in chromatography which employs ultraviolet radiation

rather than a flame to ionize compounds as they pass through.

a detector. Photoionization detectors are particularly sensitive to aromatic compounds.

Polarity: The measure of an electrical charge on a molecule. Most flammable or combustible liquids are nonpolar.

Many water soluble compounds,. including alcohols and

acetone, are polar.

Polymer: A large molecule consisting of repeating units of

a monomer. Polymers may be natural, such as cellulose, or

synthetic, such as most plastics.

Programming: A method of gas chromatographic analysis

which reproducibly raises the temperature of the column so

as to allow better resolution of the components over a wide

range of boiling points.

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Propane: An alkane having the formula C3H8. Propane is

the major constituent of LP gas. Explosive limits of 2.4% to

9%. One cubic foot of propane has a heating value of 2500

BTU’s.

Pseudocumene: (1,2,4-trimethyl benzene) A component of

gasoline.

Pyrolysis: The transformation of a substance into one or

more other substances by heat alone without oxidation.

Pyrophoric Distillation: The slow drying and passive

pyrolysis of wood materials.

-RRadiation: 1) Transfer of heat through electromagnetic

waves from hot to cold. 2) Electromagnetic waves of energy

having frequency and wavelength. The shorter wavelengths

(higher frequencies) are more energetic. The electromagnetic spectrum is comprised of a) cosmic rays, b) gamma

rays, c) x-rays, d) ultraviolet rays, e) visible light rays,

f) infrared, g) microwaves and h) radio waves.

Resolution: 1) In chromatography, a measure of the separation of components. 2) In spectroscopy, a measure of the

ability of the instrument to detect individual absorbance

peaks.

Retention Time: The length of time required for a compound or component of a mixture to pass through a chromatographic column.

-SSaturation: The state in which all available bonds of an

atom are attached to other atoms. Alkanes are saturated.

Olefins are unsaturated.

Spalling: Destruction of a surface by frost, heat, corrosion,

or mechanical causes. Concrete exposed to intense heat may

spall explosively. Expansion and contraction of the concrete

as well as vaporizing moisture contained in the concrete

contribute to this effect. It does not necessarily mean an

accelerant was used.

Spectrophotometer: An analytical technique devoted to

the identification of the elements and the elucidation of

atomic and molecular structure by measurement of the

radiant energy absorbed or emitted by a substance in any of

the wavelengths of the electromagnetic spectrum in response to excitation by an external energy source.

Spontaneous Heating: Also known as Spontaneous Combustion. Initially, a slow, exothermic reaction at ambient

temperatures. Liberated heat, if undissipated (insulated),

accumulates at an increasing rate and may lead to spontaneous ignition of any combustibles present. Spontaneous

ignition occurs sometimes in haystacks, coal piles, warm

moist cotton waste, and in stacks of-rags coated with drying

oils such as cottonseed or linseed oil.

Styrene: Vinylbenzene. An aromatic compound having the

formula C6H5C2H3. The monomer of polystyrene plastic. A

common product of polymer pyrolysis.

Substrate: Matrix. The material from which a substance to

be analyzed is removed.

Sulfur: A nonmetallic yellow element. A constituent of

black powder, sulfur burns readily when in powdered form.

Terpenes: Volatile hydrocarbons which are normal constituents of wood.

Thermal Conductivity Detector: A type of gas chromatographic detector which is sensitive to the change in the

ability of the gases emerging from the column to conduct

heat. A thermal conductivity (TC) detector is not as

sensitive as a flame ionization detector,’ but is capable of

detecting some molecules; such as water, which give no

signal in FID.

Thin Layer Chromatography (TLC): A procedure for

separating compounds by spotting them on a glass plate

coated with a thin (about 0.01 inch) layer of silica or

alumina, and “developing” the plate by allowing a solvent

to move upward by capillary action. TLC is especially

useful for identifying and comparing materials which are

highly colored or which fluoresce under ultraviolet light.

TLC is used extensively in explosive analysis and in the

comparison of gasoline dyes.

Toluene: Methylbenzene. An aromatic compound having

the formula C6H5CH3. A major component of gasoline.

Toluene has a flash point of 40°F and explosive limits of

1.2% to 7%.

Turpentine: 1) Gum. The pitch obtained from living pine

trees. A sticky viscous liquid. 2) Oil. A volatile liquid

obtained by steam distillation of gum turpentine, consisting

mainly of pinene and diterpene. Turpentine is frequently

identified in debris samples containing burned wood.

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-VVaporization: The physical change of going from a solid

or a liquid into a gaseous state.

Volatile: Prone to rapid evaporation. Both combustible and

noncombustible materials may be volatile.

-XX-ray Diffraction: An analytical technique used to identify

crystalline solids by measuring the characteristic spaces

between layers of atoms or molecules in a crystal. X-ray

diffraction can be very useful in the identification of explosive residues.

X-ray Fluorescence: A spectrophotometric analytical technique which uses x-rays to excite the samples. X-ray

fluorescence will allow the characterization of the elemental

content of a sample.

Xylene: Dimethylbenzene. An aromatic compound having the

formula C6H4(CH3)2. Xylene is a major component of gasoline.

A mixture of toluene and xylene is frequently used as automotive

paint thinner. Xylene is actually a mixture of three isomers, ortho,

meta and para xylene, which have the methyl groups in different

positions relative to each other on the benzene ring. The flash

points of these isomers range from 81° to 115°F. Paraxylene, with

a flash point of 81°F, is used to calibrate flash point testers. The

explosive limits of xylene are 1.0% to 7.0%.

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