OSACFire & Explosion Investigation Subcommittee

This process map provides a visual description and attempts to represent all reasonable variations of casework currently performed by fire investigators. OSAC does not necessarily support or endorse (as best practices) all of the different steps and paths depicted in this process map.

Fire Investigation ProcessMap (Current Practice) Mar 14, 2023 PAGE1

Introduction

The National Institute of Standards and Technology (NIST) facilitated the development of the Fire Investigation Process Map through

a collaboration between the NIST Forensic Science Research Program and the NIST-administered Organization of Scientific Area

Committees (OSAC) for Forensic Sciences (specifically OSAC?s Fire & Explosion Investigation Subcommittee). Process mapping

visually represents the critical steps and decision points of a workflow, allowing others to understand a process and its components

more clearly and revealing areas of improvement. Process maps use standard symbols to describe each element in the process ?

e.g., inputs, outputs, decisions, and steps ? making it easier to communicate a process than long-form documentation.

The Fire Investigation Process Map captures the decision-making and process flow details most frequently encountered in the

discipline of forensic fire investigation. It was developed by a diverse group of practitioners and is intended to reflect current

practices within the field, although not every step in this process map may be applicable to every fire or explosion incident. The Fire

Investigation Process Map depicts variations in practice that may be influenced by agency size, agency type (public vs. private),

agency policies, geographical location and jurisdiction. Certain processes represented in the map have a required sequence while

other components may vary. For this reason, it is important to state that the OSAC Fire Investigation Subcommittee does not

necessarily support or endorse (as best practices) all of the different steps and paths depicted in this process map.

Process Map Applications:

The Fire Investigation Process Map is intended to be used to help improve efficiencies while reducing errors, highlight gaps where

further research or standardization would be beneficial, and assist with training new investigators. It may also be used to develop

specific investigative policies and identify best practices.

Scope of the Fire Investigation Process Map:

The scope of the Fire Investigation map is limited to core processes within the discipline of fire investigation such as data collection,

data analysis, and origin and cause determination. Several forensic fire investigation related activities were not mapped including

evidence disposition, the development of supplemental reports, and trial preparations. These topics may covered in future process

mapping exercises.
OSACFire & Explosion Investigation Subcommittee

This process map provides a visual description and attempts to represent all reasonable variations of casework currently performed by fire investigators. OSAC does not necessarily support or endorse (as best practices) all of the different steps and paths depicted in this process map.

Fire Investigation ProcessMap (Current Practice) Mar 14, 2023 PAGE2

2000 Data Collection

6000 Other - Not covered in thismap*

1000 Pre-SceneActivities

3000 Origin Determination

4000 Cause Determination

5000 Reporting

Fire Effects

Assignment

Mission Received

Underlined Word

Word that will be defined

in the glossary

Input Box Outlinesthe inputsat

the beginning of each section

Output Box Describesan

output of the

steps on the

page

Discontinuation

of Assessment

or Examination

Witness

Information

Issue Report

DataAnalysis

Technical

Review

Administrative

Review

Deposition and

Trial

General

Observations

Fire Pattern

Analysis

Fire Dynamics

Analysis

Supplemental

Reports

Evidence Disposition

Legend

Processstart/end

Process

Decision

Subprocess

Document

Results of

Reconstruction

Notifications Property

Information

EffectsDue to

Fire

Suppression

Activities

Initial Witness

Information

Hypothesis Development

Hypothesis

Testing

Hypothesis

Development

SceneAccess

Hypothesis

Testing

Heat Source First Fuel

DataAnalysis

Resultsof

Evidence

Analysis

(physical)

Prepare

Report

Safety

Assessment

Witness

Information

Analysis

Other scene,

Location, and

Event-related

Data

Area of Origin

Determination

Cause

Determination Oxidizer

Reconstruction

Evidence

Analysis

(physical)

Archive

CauseSpecific

Data

Data from

Outside

Report for Review

Damage

Evaluation:

Fuel

Controlled vs

Ventilation

Timeline

Analysis

Fire

Classification

Research, General

Information, and/or

Additional

Non-case Specific Data Obtained

Scene Release

Circumstances

That Brought

Heat Source,

First Fuel, Oxidizer

Together

Linkage

TO/FROM

within the

same page

Linkage

TO/FROM

another

page

Technology Assist

Technology that aidsin the steps on this

page
OSACFire & Explosion Investigation Subcommittee

This process map provides a visual description and attempts to represent all reasonable variations of casework currently performed by fire investigators. OSAC does not necessarily support or endorse (as best practices) all of the different steps and paths depicted in this process map.

Fire Investigation ProcessMap (Current Practice) Mar 14, 2023 PAGE3

1000 Pre-SceneActivities

Receive Mission

1002

Input

Information Received

(See Information Received)

Information Received

Detailsmayinclude:

- Date of loss

- Fire location

- Property type and scope (residential, commercial, vehicle, wild land,

boat, crops, equipment, other property)

- Extent of damage

- Safety re: known presence of hazardsand hazardousmaterials

(e.g., asbestos, clandestine drug lab)

- Precursory safety review

- Fatalities/Injuries

- Media reportsor public records

- Jurisdiction

- Who will be in charge of scene/investigation from public sector

- Other partiesinvolved

- Conflict check- any known relationshipsw interested/involved

parties?

- Who isalso on notice

- If insured property

- If appliancesor other equipment involved (e.g.,mfr or installer,

etc.)

- Personnel onsite (or will be called to be onsite)

- Public investigator

- Fire department

- Private investigator (Investigator for insurance company that

insuresthe property, and/or contents)

- Manufacturers(piece of equipment)

- Put on notice and invited to participate in investigation

- Attorney representing the insurance company

- Trade personnel (HVAC, Plumbing, Electrician, etc.)

- Any protocolsalready in place

- Safety

- Evidence collection (incl. any sifting done on site)

- Evidence retention

- Which lab evidence will go to

- Equipment involved

- Manufacturer information (make and model)

- Equipment needed (e.g., crane)

1010

Inquire and note who hasalready

been at the scene

1016

Communicate with partner

agencies

1006

Pre-scene actions: Based on

investigation, conduct activitiesas

needed or per agency policy (PAP)

1008

Obtain permission to enter

property (or warrantsif necessary)

1014

Notify interested parties

1018

Identify and secure appropriate

equipment

1012

Contact party in control of

property (e.g., incident command,

owner, etc.)

1024

Conduct pre-scene interviews

1020

Obtain information on property

use

1022

Obtain media reports

GO TO

1200

SceneAccess

(Page 2 of 3)

GOTO

1400

Witness

Statements

(Page 3 of 3)

1026

Are there partiesthat

need to be notified (e.g., Property owner, manufacturers,

insurance company,

attorney, etc.)?

1028

Have partiesbeen put

on notice?

1030

Put partieson notice

(e.g., send lettersto

other entities, etc.)

No

Yes

No

1031

Are all necessary steps

complete?

Yes

No

Yes

1034

Output:

- Established need for services

- Information on when fire happened, type of

occupancy, info on extent of damage

- Plan to move forward (e.g., formal or

informal, logistics, equipment, etc.)

- Timeframe needed for work to get done

- Permission to enter property

- Necessary partiesput on notice

- Witnessinformation (e.g., video electronic or

other)

- Possible initial witness interviews

- Safety plan

- Awarenessof hazards

- Possible safety briefing GOTO

2000

Data Collection

FROM

1250/1512

1032

Conduct safety assessment and develop

safety plan PAP:

- Identify hazards

- Determine necessary documentation, mitigation, and/or avoidance of hazards

or other safety issues

- Evaluate what PPEmay be required for

to investigate inside the scenesafely

1033

Determine and conduct any

additional safety activities(if

any) PAP:

- Conduct safety briefing

- Document safety plan

- Note safety concernsfor

personal awareness
OSACFire & Explosion Investigation Subcommittee

This process map provides a visual description and attempts to represent all reasonable variations of casework currently performed by fire investigators. OSAC does not necessarily support or endorse (as best practices) all of the different steps and paths depicted in this process map.

Fire Investigation ProcessMap (Current Practice) Mar 14, 2023 PAGE4

Return to Overview 1200 SceneAccess

1232

Seek search warrant

1242

Seek consent PAP

1240

Seek consent

from owner/tenant per

agency policy

(PAP)?

1244

Consent

obtained?

1220

Are there exigent

circumstances?

1222

Isthe property

owner/tenant

available?

1214

Perform other tasksas needed while awaitingaccess: (e.g.,

take photosfrom distance,

interview, look at neighboring

buildingsfor security videos,

etc.)

1202

Public

investigation?

1204

Permission received to

enter scene?

Scene Access

- Accessmay be allowed aspart of

the contract

- May need consent if owner did not

have insurance and need consent

from owner- may also be an

attorney involved and also injuries

and death

- Negotiate w public investigatorsfor

equipment in exchange for access

1206

Seek permission

to enter scene

for photographs

1224

Isthere

probable

cause?

1208

Permission granted?

1250

Output: Granted access

to scene viapermission

to enter property or

exigent circumstances

1234

Warrant

obtained?

1216

Continue?

1238

Resubmit

amended search warrant

1226

Seek administrative warrant

1228

Warrant

obtained?

1210

Isa court

order needed to enter

property?

1212

Seek court order?

RETURN TO

1032

1246

Enter under

exigent

circumstances?

1236

Resubmit?

1248

Contact and/or

await permission

to enter (per

jurisdictional

policy)

1218

Do federal and state

statutesdictate that other

public agenciesneed to be

notified (see Other Agency

Notifications)?

1230

Schedule time to

accessscene

FROM 1008

Yes

No

Yes

No

Yes

Other Agency Notifications*:

- Church/religiousestablishment

- Fatalities

- Bombings

*Per NFPA921

No

Yes

Yes Yes

No

No

No

No No

Yes

No

GOTO1250

Yes

Yes

Yes

No

No

Yes Yes

STOP/

GOTO

Reporting

No

STOP/

GOTO

Reporting

No

STOP/

GOTO

Reporting

No

STOP/

GOTO

Reporting

Yes

Yes

No

No

Yes

Yes
OSACFire & Explosion Investigation Subcommittee

This process map provides a visual description and attempts to represent all reasonable variations of casework currently performed by fire investigators. OSAC does not necessarily support or endorse (as best practices) all of the different steps and paths depicted in this process map.

Fire Investigation ProcessMap (Current Practice) Mar 14, 2023 PAGE5

1400 WitnessInformation

Return to Overview

1410

Can interviewsbe

obtained?

1406

Identify and document contact information for individualsthat have information leading up to the fire

event, knowledge of the fire event, and/or knowledge of the scene from post fire event

1508

Output:

- Timeline and narrative

- Fire growth and spread

narrative

- Understandingof condition of

property and activities

(including people) before the

fire

- Possible digital information

about the fire, property,

security, etc.

- Fire origin and cause

FROM 2008

FROM

1024

Fact Witnesses*

- Knowledge of incident

- Knowledge about property

- Knowledge of incident and property

- Knowledge of equipment, appliances, or systems

(e.g., manufacturersor installers)

*May possessknowledge of other factssuch ascondition

of property and activitiesbefore and after the fire

Incident-Related Witnesses

- Firefighters

- Police officers

- Security guards

- Employees

- 911 Operator(s)

- Occupants

- Owners

- Fire discoverer

- Observers

- 911 or other emergency line caller

GOTO

2004

Data Collection: WitnessInfo

RETURNTO

1006

1510 - Based on Investigation:

RETURNTO

4000

Cause Determination

1414

Re-conduct?

Digital Witnesses*

- Security camerasystems

- Fire protection systems

- Burglar and intrusion systems

- Electrical and gas distribution systems

- Smart appliances

- Computer systems

- Cellular telephonesand other communication devices

- Manufacturing and distribution systems

- HVACsystems

- 911 or other emergency recording/transcript

*Consent or a search warrant may be necessary to obtain information

and/or devices depending on circumstances

1408

Determine whether anyone has

already conducted event or fact witnessinterviews

1416

Identify and document all the

fact witnesses(See Fact

Witnesses)

1426

Identify and document all

incident-related witnesses(See

Incident-Related Witnesses)

1502

Conduct interview(s) and document

witness information:

- Whether there will be multiple/staged

interviews (e.g., due to access,

chronology, injury, etc.)

- Whether there are potential appliances

or other equipment involved

1500

Determine whereand how

interviewswill be conducted

(e.g., location, level of detail,

by what means, whether

concurrent with walk

through*, how will the

interview be documented, etc.)

1504

Have all witness interviewsbeen

conducted?

1402

Input

- Initial pre-scene information collected and/or

on-scene information

- Preliminary scene information (may include

safety, scene security, etc.)

Yes

No

Yes

Yes

Yes

1412

Obtain interviewsand

obtain available

information

Yes

No

RETURN TO

1406 No

1512

Interview(s) conducted

pre-scene?

1514

Were interview(s) conducted

asa result of data collection for origin

determination

activities?

1516

Were interview(s)were

conducted as part of additional

cause related data

collection?

*Walk-through with

occupantsor witnesses may take place later in

the investigation due to

hazardsand any

necessary remediation;

also allowing

investigatorsto

formulate appropriate

focused questions.

1506

Isthere digital witness

information or data to collect?

(See Digital Witnesses)?

RETURN TO

1406

Yes

No

1507

Document where and how digital devices,

information, or data wascollected, e.g.:

- Type of device, equipment, or other

source

- Type of file, storage, etc.

- Information on owner/person in

possession of device or information from

device, equipment, or other source

Yes
OSACFire & Explosion Investigation Subcommittee

This process map provides a visual description and attempts to represent all reasonable variations of casework currently performed by fire investigators. OSAC does not necessarily support or endorse (as best practices) all of the different steps and paths depicted in this process map.

Fire Investigation ProcessMap (Current Practice) Mar 14, 2023 PAGE6

2000 DataCollection (1 of 4)

FROM 4004/4028/

4348

Return to Overview

2002

Input

- Established need for services

- Information on: when fire happened, type of occupancy,

info on extent of damage

- Witnessinformation (e.g., video electronic or other)

- Plan to move forward (e.g., formal or informal, logistics,

equipment, etc.)

- Timeframe needed for work to get done

- Permission to enter property

- Necessary partiesput on notice

- Possible initial witnessinterviews

FROM

1034

General Observations

2030

During walk-through document

observationse.g.,:

- Olfactory

- Audible

- Visual:

- Ventilation sources: location and

condition of vents for exhaust and

intake, e.g., windows, doors, etc.

- Buildingand room characteristics

- Dimensions

- Fuels(things that may have or could

have burned)

- Contents

- Thingsmoved out

- Bare home

- Liningmaterials

- surfacesof the room and

assemblies (e.g., wall type and material used, etc.)

- What hasbeen disturbed

- Buildingsystems(may be olfactory,

audible, and visual)

2032

If a warrant hasnot

already been obtained, are

there indications that

awarrant isneeded to

continue?

GO TO

1220

Scene Access

Yes

No

2004

Conduct data collection activitiesas needed

per stageof investigation*:

*Data collection isongoingirrespective of investigatory

stage and the data contained in thisbin representsall data

from any investigative stage

2010

Fireeffects

2008

Witness

information,

including

electronicdata

2006

General

observations

2012

Effectsdue to

fire

suppression

activities

2014

Resultsof

analyses:

physical,

laboratory,

reconstruction,

etc.

2016

Other scene,

location, and

event-related

data

2018

Cause-specific

data

2020

Datafrom

outsidereport

under review

GOTO

2050

FireEffects

(Page2 of 4)

GOTO

1406

Witness

Information

GOTO

2080

FireSuppression

Activities

(Page2 of 4)

GOTO

2090/2092/2094

2096

Results

GOTO

2100

Other Scene,

Location, and

Event-Related Data

(Page 4 of 4)

GOTO

2120

Cause-Specific Data (Page4 of

4)

GOTO

2130

Data from

Outside (Page 4

of 4)

RETURN TO

4000

Cause Determination

GOTO

3000

Origin Determination: DataAnalysis/

Interpretation

RETURN TO5036

Tech Review

(Reporting)

2038

Have all known and available

potentially relevant data been

identified and collected?

No

Yes

2034

Continuewith walk

through and/or scene

investigation activities

PAP

RETURNTO

2004

2036

Assessdata collection:

- Observe, and determine how to best

document data collected, e.g., saved,

photographed, noted, maintained or

otherwise preserved in some way

- Begin to assess whether data isrelevant

to the investigation at this time (reserving

the right to return to any data for

re-assessment further in the investigation)

RETURN TO

2004

FROM

3060

GOTO

2140

Research, general

information, etc.

(Page 4 of 4)

2022

Research, general

information,

and/or additional

non-case specific

dataobtained

2040

Choose appropriate path based

on investigation:

FROM

1510/2034/2038/

2064/2066/2074/2076

2080/2090/2092/

2094/2096/2100

2120/2130/2140

FROM 5138/5142

2003

Initiate walk-through GOTO

DataCollection:
OSACFire & Explosion Investigation Subcommittee

This process map provides a visual description and attempts to represent all reasonable variations of casework currently performed by fire investigators. OSAC does not necessarily support or endorse (as best practices) all of the different steps and paths depicted in this process map.

Fire Investigation ProcessMap (Current Practice) Mar 14, 2023 PAGE7

Return to Overview 2000 DataCollection (2 of 4)

Fire effects

2050

Assessfire effects

(including effectson

building systemse.g.,

alarms, sprinklers, HVAC,

utilities, etc.)

2052

Evaluate characteristics

of fire effect(s) and

combination of effects

2062

Conduct samplingand localized examination

to understand effectsfurther (includingany

collection and storage of evidence to preserve

chain of custody) e.g.,:

- Samplesof material for further analysis

- Material from cleaningsurface (i.e. soot

removal)

- Decomposition products (may be char

depth related also)

2064

Conduct testingon items?

2060

Perform sampling?

2058

Conduct measurements

(e.g., char depth,

calcination depth,

etc.)

2066

Request testingon

evidence items

2056

Take measurements?

Yes

No

Yes

No

Yes

No

FROM

2010

RETURN TO

2004

2054

Document observationsof fire

effectsand characteristicsthrough

notesand/or photography (see Fire

Effectsand FireEffects Characteristics)

Fire Effects Fire EffectsCharacteristics

- Discoloration/color change

- Oxidation

- Rainbow effect

- Stainingof glass

- Deformation

- Structural deformation

- Alloying

- Breakingof glass

- Collapsed furniture springs

- Distorted light bulbs

- Melting

- Thermal expansion

- Blistering

- Deposition

- Deposition of smoke on surfaces

- Smoke alarms

- Enhanced soot deposition

- Massloss

- Measurement of:

- Calcination depth

- Char depth

- Massloss(e.g., weight or other measurement to

evaluate how much of an item hasburned)

- Spalling (e.g., chipping, crumbling)

- Arcsites/arcing events and artifacts

- Arcmark

- Beadingof the metal

- Severing the conductor

- Corresponding notchesin conductors

- Massloss/deformation- connected to these

features

- System fire effects(on alarm, HVACsystems, etc.):

- Failurepattern

- Buildingsystemsaffected

- History of alarm conditions(e.g., activation or

failure of device)

- Thermal decomposition:

- Photos, diagrams, notes, where thingsoccur

- Characteristics; color changes, mass loss, melting, etc.

- Absenceof soot:

- Possibly from "clean burn" (e.g., enough heat to burn

off soot- no soot on wall asit hasbeen burned off,

thermally effected but no soot there; also protected so

there isalso an absence of soot

- Magnitude

- Propertiesof material

- Circumstantial context

- Gradient

- Size

- Color

- Location

- Shape

- Geometry

- Orientation

- Timing or sequence of events related to system

- Depth

- Proximity to other feature(s)
OSACFire & Explosion Investigation Subcommittee

This process map provides a visual description and attempts to represent all reasonable variations of casework currently performed by fire investigators. OSAC does not necessarily support or endorse (as best practices) all of the different steps and paths depicted in this process map.

Fire Investigation ProcessMap (Current Practice) Mar 14, 2023 PAGE8

Return to Overview 2000 Data Collection (3 of 4)

EffectsDue to Fire Suppression Activities

2080

Assesseffectsdue to firefighting

operations, fire suppression activities,

and overhaul including any resulting

sourcesof ventilation (See Effectsdue

to Suppression/Overhaul)

FROM

2012

RETURN TO

2004

Resultsof Analyses

Consider all that apply:

FROM

2014

2090

Pre-fire conditions/content analysis

(may be based on observations,

interviews, reconstruction, photos,

videos, witnesses, electronic data from

systems)

2092

Laboratory Data (Off Scene)

- Metallurgical data

- Crystal structure (metals), what elementsare present

- Chemical and materialsscience data

- Physical measurements(gauge of wires, etc.)

- Temperature measurements

- Electrical measurement

- Destructive (may need permission or get concurrenceof

parties) and non-destructive (e.g, CTscansof an item or

equipment/device)

- Mechanical testing

- Stresstesting

- Electrical artifacts- localized damage indicatingelectrical

failure)

- Materialsanalysis

- Ignitability of a fuel

2094

Results of modelingfor

hypothesistesting, subsequent modeling, scale testing, or other

analyses

2096

Results of fire scene

reconstruction

RETURN TO

2004

EffectsDue to FirefightingSuppression/Overhaul (including sourcesof

ventilation):

- Penetrations into walls or ceilings

- Drive fire from oneportion of building to another

- Offensive vs. defensive

- Salvage (e.g., protectingcontents)

- Ex. Salvage cover: tarpsover itemsto prevent destruction; can also be

used aswater shoots

- Overhaul (e.g., ensure fire isextinguished)

- Items that were in the room/other roomsmay have been moved by

the fire department or an investigator, crew, etc. and may be mixed

together outside or in another area.

- Forced entry

- Opened doors

- Holes in roof

- Knocked down wallsduring suppression

- Broken windows

- Disconnection of utilities; (also may be related to arc mapping)

- Turning off breakers

- Bringing equipment into building- can be destructive to patterns

- Gaspowered equipment, equipment with oil coating, etc.
OSACFire & Explosion Investigation Subcommittee

This process map provides a visual description and attempts to represent all reasonable variations of casework currently performed by fire investigators. OSAC does not necessarily support or endorse (as best practices) all of the different steps and paths depicted in this process map.

Fire Investigation ProcessMap (Current Practice) Mar 14, 2023 PAGE9

Return to Overview 2000 Data Collection (4 of 4)

Other scene, location, and event-related data

2100

- Maps

- Digital/electronic evidence (e.g.,

phone, video, smart home

appliances, etc.)

- Blueprints/building permit

information

- CCTVinformation

- Weather

- GPStracking

- Building utility mapsand status

- Dispatch information

- Communication logs

- Injuries

- Autopsy results

FROM

2016

Subset of Data Related to Cause

2120

- Human activity around the time and location of fire

- Potential ignition sources(consider all potential ignitionsourcesinarea of origin)

- Heating device

- Smoking materials

- Electrical

- Appliances

- Mechanical equipment

- Open flame devices

- Lightning

- Fire DebrisAnalysis(e.g., gas, lighter fluid, fuels)

- Consumer products

- Chemicals

- Materialsrelated to spontaneouscombustion or self-ignition

- Damage patterns

- Self-heating(internal to object)

- Damage to devicesor lack thereof- damage inside or outside

- Fuel considerations

- Fuelspresent in area of origin (and ignitability via ignition sources)

- Intentions

- Source placement

- Source location

- Types

- Atypical (not normally present)

- Oxidants

- Proximity

- Re pyrolysis- dependent on what the oxidant is(air vsa chemical vs99%O2, etc.)

- Concentration of the oxidant- normal air vspure oxygen

- Amount

- Failure modes(e.g., pure liquid oxygen escaped from pipe, etc.)

- Physical proximity of potential ignition source to fuelswithin the area of origin

- Timeline analysisof fire event

FROM

2018/4352/

5140

Data from Outside Report for Review

2130

May contain data includingbut not limited to:

- Observations

- Fire effects

- Firefightingoperations effects

- Witnessstatements

- Non-scene data

- Resultsof analysis

- Cause-related data

- Other

FROM

2020

RETURN TO

2004

RETURN TO

R 2004 ETURN TO

2004

Research, general information, and/or additional non-case specific data obtained

2140

Research (e.g., Literature review; sourcesof information: magazines, scholarly research, peer reviewed journal, ATF, Ignition Handbook, Consumer Product Safety

Commission (CPSC), manufacturer information, product manuals, etc.)

FROM

2022

RETURN TO

2004

2121

Are there

any notifications that

need to takeplace dueto

cause-specific

data?

No

Yes

2022

Put partieson notice

(e.g., send lettersto

other entities, etc.)
OSACFire & Explosion Investigation Subcommittee

This process map provides a visual description and attempts to represent all reasonable variations of casework currently performed by fire investigators. OSAC does not necessarily support or endorse (as best practices) all of the different steps and paths depicted in this process map.

Fire Investigation ProcessMap (Current Practice) Mar 14, 2023 PAGE10

Return to Overview 3000 Origin Determination: Data Analysis

FROM

2040

3002

Input: Data related to

variousstagesof the

investigation including

(but not limited to):

- General observations

- Fire effects

- Witnessinformation

- Effectsdue to fire

suppression

- Resultsof analyses

- Non-scene data

- Cause-specific data

- Data from outside reports

3012

Conduct fire pattern analysis(e.g., arc mapping, etc.) noting:

- Identification of patterns

- Evaluation of whether patterns are

explainable and/or expected considering

timeline, fire dynamicsand other factors

- Assessment of what caused the fire effects we are now identifying asa pattern

- Evaluation of surfacesfor charring (e.g., are

all exposed surfacescharred?)

- Assessment of damage (e.g., whether due

to ventilation, intensity, or duration, etc.)

3036

Conduct fire scene

reconstruction

3006

Conduct fire effectsanalysis, e.g.,:

- Short term higher heat

- Long term lower heat intensity

- Firefighters

- Effectscaused by them

- Fire movement influenced by

firefighting

3030

Perform fire dynamicsanalysis

(e.g., the physicsand chemistry of

fire initiation and growth,

ventilation openings, and the

interaction between the fire and

the buildings

systems)

3004

DataAnalysisand Interpretation: Assign meaning to collective fire patternsand other data asapplicable and potentially assess credibility of data pointsasanalysesare conducted throughout investigation

(choose all that apply):

3038

Witnessanalysis(including

electronic witnessanalysis)

3034

Conduct analysison evidence

items

3008

Do fire effectsconstitute

a pattern?

3050

Output: Meaning of data including (but not limited to) an understandingof:

- Analyzed data and resultsof analysesin the context of fire dynamics

- Growth and spread of the fire

- Meaning and connectednessassigned to the physical evidence,

observations, etc.

- Heat, smoke, and ventilation flow

- Damage/consumption of items

- Fire effects

- Thermal conditionsin certain locations

- Cause of fire effects now identified as apattern

- Any potential inconsistencies in the data and the possible reasonsfor this

determination

- Timeline of events

- Range of uncertainty for each data point

- Witnessstatements and/or perceptions

- Which fire patterns are fuel controlled vs. ventilation controlled

- Which fire patterns are most meaningful to the investigation

- Understandingof how and when fire patterns may have occurred

GOTO

3200

Origin Determination:

Hypothesis Development and

Testing

Key: Hashed linesindicate resultsfeed

into the next stepsin either direction

No

3032

Conduct timeline analysis(e.g.,

timingof events leadingup to

and during the fire)

Yes

3022

Conduct fire pattern(s)

analysis hypothesis

testingto understand how

and when the pattern(s) was(were) formed

3020

Consider identified

patterns in context of one

another aswell as

ventilation points

3054

Assessdata collection

e. g., Evaluate whether to

seek additional data

based on analysis so far

3055

Generate hypotheses

for origin

determination?

3024

Output:

Information regarding:

- Which fire patterns are fuel

controlled vs. ventilation controlled

- Which fire patterns are most meaningful to the investigation

- Understandingof how and when

fire patterns may have occurred

3056

Choose appropriate path based on investigation:

3060

Revisit potential

sourcesof data(e.g.,

conduct more

interviews, wait for

laboratory results, etc.)

No

Yes

Yes

RETURN TO5036

Tech Review

(Reporting)

RETURN TO

2004

RETURN TO

4000

Cause Determination

RETURN TO

3004

3010

Continue to

other analyses

asneeded

FROM 3010

FROM 3214/3220

4360/5150

3052

Are there

any notifications that need to

takeplace dueto

analyses?

No

3053

Put partieson notice

(e.g., send lettersto

other entities, etc.)

FROM

4350/5144
OSACFire & Explosion Investigation Subcommittee

This process map provides a visual description and attempts to represent all reasonable variations of casework currently performed by fire investigators. OSAC does not necessarily support or endorse (as best practices) all of the different steps and paths depicted in this process map.

Fire Investigation ProcessMap (Current Practice) Mar 14, 2023 PAGE11

Return to Overview 3200 Origin Determination: HypothesisDevelopment and Testing

FROM 3055

3202

Input

An understandingof:

- Analyzed data and resultsof analysesin the context of fire dynamics

- Data points

- Growth and spread of the fire

- Meaning and connectednessassigned to the physical evidence, observations, etc.

- Heat, smoke, and ventilation flow

- Damage/consumption of items

- Thermal conditionsin certain locations

- Cause of fire effectsnow identified asa pattern

- Any potential inconsistenciesin the data and the possible

reasonsfor thisdetermination

- Timeline of events

- Range of uncertainty for each data point

3204

Consider or develop hypotheses

based on data analysis

(formulate all hypotheses

supported by the data and

totality of the circumstances)

3206

Select ahypothesisfor

testing(see Hypothesis Testing Considerations)

3210

Isthe hypothesisconsistent with relevant scientific knowledge and

all analyzed case and test data?

(see HypothesisTesting

Considerations)

HypothesisTesting Considerations:

Determine how to sufficiently test the hypothesis:

- Research: preliminary step- do I know how to

appropriately test thishypothesis?

- Lit review; sourcesof information: magazines,

scholarly research, peer reviewed journal, ATF,

Ignition Handbook, Consumer Product Safety

Commission (CPSC), etc.

- Apply knowledge of fire science

- Scale testing: recreate scene and burn

items/materialsdown; possible full recreation

- Mental Exercise: non-lab testing, literature review,

assesscompetence of hypothesis

- Computer/electronic modeling

3218

Document resultsof hypothesis

testing

3208

Test hypothesisby applying deductive reasoning to

compare hypothesisto all analyzed case and test

data, and scientific knowledge (e.g., fire science).

Testing may include any application of fundamental

principlesof science, physical experimentsor

testing, cognitive experiments, analytical techniques

and tools, and system analysis.

Techniquesmay also employ toolssuch as:

- Fire dynamicsanalysis

- Field testing

- Experimental testing

- Computer modeling

- Scientific literature

- Timelines

Yes

3212

Document resultsof hypothesis

testing

No

Yes

3222

Select another hypothesis

for testing?

3224

Hasmore than one

hypothesissurvived

testing?

3226

Have any survived

testing?

RETURNTO3206

3234

Are the areasof damage

separate and

unconnected?

3236

Doesit appear that the

fire started in one area

and spread to

another?

Yes

No

Yes

No

Yes

No

Yes

No

Yes

No

No

3250

Choose appropriate path based on investigation:

GOTO4000

Cause Determination

RETURNTO5036

Tech Review

(Reporting)

3220

Is additional data analyses warranted?

3214

Isadditional data analyses warranted?

RETURN TO

3004

RETURNTO

3004

Yes

No

3240

Output: Delineate multiple

areasof origin

3242

Output: Determine onearea

of origin

3230

Output:

Determine one area

of origin

3228

Output:

Areaof origin is

determined to be the

area of scene

3216

Output:

Eliminate hypothesis

3238

Output:

Expand areato cover any

hypotheses that cannot

be eliminated aspart of

the origin
OSACFire & Explosion Investigation Subcommittee

This process map provides a visual description and attempts to represent all reasonable variations of casework currently performed by fire investigators. OSAC does not necessarily support or endorse (as best practices) all of the different steps and paths depicted in this process map.

Fire Investigation ProcessMap (Current Practice) Mar 14, 2023 PAGE12

4000 - 4100 CauseDetermination: Evidence Identification, Data Analysis, and HypothesisDevelopment

CauseEvidence Identification and Collection Based onArea of Origin

Return to Overview

DataAnalysis: Throughout, conduct research asneeded - e.g., lit review; sourcesof information such asmagazines, scholarly research, peer reviewed journal, ATF, ignition handbook, Consumer Product Safety Commission (CPSC), safety data

sheets(SDS), etc.; Review and update timeline asneeded

4150

Develop cause hypotheses for testing

Consider:

- All potential ignition sourcesin the

area of origin

- All proximate fuels/combustiblesto the

ignition source(s)

- All possible ignition sequences

supportable by the ignition source and

fuel combination(s)

- All other analyzed case data (e.g., whether the scenario(s) are plausible

to fit the rest of the data and

observationssuch aswitnesses, digital,

or other data)

4100

Characterize all ignition (heat) sourcesin area of origin:

Consider the following examplesbased on potential

scenario(s):

- How hot doesit get?

- How much energy doesit have?

- How doesthe energy get transferred out?

- Configuration of the item (i.e. how doesthisitem

transmit heat onto other things?Thiscan also be

impacted by the configuration of the ignition

source)

- Heat release rate relative to time

- Human error or device failure (e.g., faulty failure mechanism)

- Wasignition related to the fuel (e.g., did the fuel

have the potential for self-heat/ignite?)

- Mechanism that brought the heat source to the fuel

- Duration of heating event

- Duration of activitiesleading up to the ignition

- Safety mechanismspresent (or absent) within a

device

4102

Characterize all fuelsin area of origin:

Consider the following examplesbased on potential scenario

and ignition (heat) sources:

- Identify the fuel

- Determine whether it isa solid, liquid, or a gas?

- What are the ignition properties(e.g., ignition

temperature for solid, and lower flammability limit

(LFL) for a gas)?

- What are itsthermal properties(e.g., ability to

absorb and conduct heat; the fuel capabilitiesto

absorb and retain heat energy to initiate

combustion)

- Conductivity

- Density

- Specific heat

- Absorptivity

- Doesthisfuel require an external ignition source

(e.g., wasthere a possibility for self-ignition)?

- Surface area to volume ratio (e.g., thin paper vs.

thick cardboard, etc.)

- Pyrolysismechanism and kineticsof the process

- Geometry and orientation (e.g., stack of paper vs.

crumpled)

4104

Characterize all oxidants in areaof

origin (e.g., air, other chemicals, etc.):

- Concentration

- Amount

- Proximity to ventilation

- Lack of ventilation (asrelated to

oxidant)

4012

Identify all proximate first fuels

(material ignited):

- In area of origin

- Proximate to ignition source

- Propertiesand configuration of

fuel source

4006

Identify all potential ignition

(heat) sourcesin area of origin

(including inferred or

consumed heat sources)

4008

Collect potential

ignition sources?

4010

Initiate collection of potential

ignition sourcesfor

preservation and/or analysis*

*to includeany necessary stepsto

appropriately document the evidence

and preserve the chain of custody

4014

Collect potential fuel

sources?

4016

Initiate collection of potential

fuel source(s) and

comparison samplesfor

preservation and/or

analysis*

*to includeany necessary stepsto

appropriately document the evidence

and preserve the chain of custody

4020

Have all ignition sources,

fuels, and oxidants (and their

combinations) in area of

origin been

inventoried?

4022

Assessdata collection (e.g., is

there any additional data,

based on the investigation so

far, needed?)

4024

Have all known and

available potentially

relevant data been

identified and

collected?

4028

Revisit potential

sourcesof data

RETURN TO

2004

No

No

Yes

Yes

Yes

4018

Identify all oxidants:

- In area of origin

- Proximate to ignition source

FROM 3232 4002

Input

Origin Determination

4004

Determine which data

collected isrelevant to

cause determination

RETURN TO

2004

FROM

2040/4212/4228/

4360/5150/5146

Yes

No

4120

Choose appropriate path based on

investigation:

RETURN TO5036

Tech Review

(Reporting)

4122

Continue with cause

analysis?

Yes

No

GOTO

4200

Cause Determination:

Hypothesis

Testing

4110

Are there

any notificationsthat need to

take place due to

analyses?

4115

Put partieson notice

(e.g., send lettersto

other entities, etc.)

Yes

No

GOTO4100

No

4106

Generate possible ignition sequences(ignition

scenarios) based on data and characterizations

of ignition source, fuel, and oxidants, e.g.:

- Analyze each ignition source in relation to

each of the proximate fuelsthat it may ignite

- Identify all viable ignition source and fuel

combinations

- Assesshow the ignition source, fuel, and

oxidant may have cometogether

4026

Evaluate timeline related

information and build

timeline of fire event based

on data, analyses, and in

context with identified

patterns
OSACFire & Explosion Investigation Subcommittee

This process map provides a visual description and attempts to represent all reasonable variations of casework currently performed by fire investigators. OSAC does not necessarily support or endorse (as best practices) all of the different steps and paths depicted in this process map.

Fire Investigation ProcessMap (Current Practice) Mar 14, 2023 PAGE13

4200 Cause Determination: HypothesisTesting

HypothesisTesting

4204

Choose one hypothesisat a time

to test:

- Ignition source

- Fuel

- Oxidant

- Sequence

4206

Test hypothesisby applying deductive reasoning to

compare hypothesisto all analyzed case and test

data, and scientific knowledge (e.g., fire science).

Testing may include any application of fundamental

principlesof science, physical experimentsor

testing, cognitive experiments, analytical

techniquesand tools, and system analysis.

Techniquesmay also employ toolssuch as:

- Scientific literature

- Field testing

- Fire testing

- Ignition testing

- Computer modeling

- Timelines

- Fault trees

4216

Additional hypotheses

to test?

4208

Isthe hypothesisconsistent with relevant scientific knowledge

and all analyzed case and test data?

(see HypothesisTesting

Considerations)

4226

Document resultsof hypothesis

testing

4210

Document resultsof hypothesis

testing

Yes

No

No

Yes RETURN TO4204

4218

Have all but one

hypothesisbeen

eliminated?

4220

Describe and document:

- Circumstancesthat brought the

ignition source into contact with

first fuel

- Failuremodes that occurred to

enable ignition

- Oxidizer

Yes

GOTO

4322

Cause Determination:: ClassifyFire

GOTO5000

Reporting

4224

Doesagency classify

fires?

Yes

No

4222

Output:

Cause determination:

- Ignition source

- First material ignited

- Oxidizer

- Ignition sequence

GOTO

4300

Cause Determination

No

4228

Isadditional data analyses warranted?

No

4212

Is additional dataanalyses warranted?

Yes RETURNTO4020

Yes RETURNTO4020

No

FROM 4150

HypothesisTesting Considerations

Consider factorssuch asthe following:

- Isthe ignition source competent/viable to ignite the fuel?

- Isignition source close enough to fuel for energy transfer to

occur?

- Wasa sufficient temperature reached on/in ignition source

to ignite the fuel?

- Wasthere sufficient intensity and/or duration for the

ignition source to interact with the first fuel ignited?

- Isthe required time for ignition consistent with the overall

incident timeline data (e.g., time stamps, other digital hard

times)?

- Isthe scenario plausible to fit the rest of the data and

observations(e.g., witnesses, digital or other data, etc.)?

FROM 4342/4344

4214

Output:

Eliminate this

particular

combination
OSACFire & Explosion Investigation Subcommittee

This process map provides a visual description and attempts to represent all reasonable variations of casework currently performed by fire investigators. OSAC does not necessarily support or endorse (as best practices) all of the different steps and paths depicted in this process map.

Fire Investigation ProcessMap (Current Practice) Mar 14, 2023 PAGE14

Return to Overview 4300 Cause Determination

4312

Doesagency provide a likelihood

for each scenario (e.g., more

likely than not; can't eliminate;

possible vs. probable, etc.)?

4326

Generate likelihood statements PAPbased on knowledge,

experience, training, and/or

research

4302

Conduct additional research,

consultation, or other

efforts?

4340

Based on knowledge, experience, and/or

agency policy select an option:

4342

Consult with another colleagueor

another type of expert

4346

Perform further data analysis

4344

Apply techniques

for hypothesistesting previously

not employed that could now be

of assistance

4350

Revisit area of origin

determination

4348

Seek additional data (Origin)

4352

Seek additional data (Cause)

4304

Report on hypotheses

eliminated?

4306

Document hypothesesthat

survive and those that did not

4308

Document undetermined

cause

4316

Doesagency classify

fires?

Yes

No

FROM 4218 Yes

No

Yes

No

RETURN TO4204

4328

Output

Likelihood statements

Yes

4314

Output

Undetermined cause

No

4360

Isadditional data

analysis required for

origin?

RETURNTOTO

3004

RETURN TO

4020

Yes

No

RETURN TO

3054

RETURN TO

2004

RETURN TO

2120

4318

Form a final conclusion

statement which may or may not

include origin, and/or cause

4322

Determine fire

classification based on

agency

definitions/parameters

for fire classification

4324

Form afinal conclusion statement which may or may not include

origin, cause, fire classification,

responsible party(ies), or other

information such as failure analysis PAP

4320

Choose appropriate path based on investigation:

GOTO

5000

Reporting

RETURNTO5036

Tech Review

(Reporting)

FROM

4224

4310

Output

Undetermined cause

(e.g., more than one hypothesisis

feasible)

Cause MUSThave:

- Ignition Source

- First Material Ignited

- Ignition Sequence (how the first

ignition material and source

interacted - with fire physics

considered aswell asproximity)
OSACFire & Explosion Investigation Subcommittee

This process map provides a visual description and attempts to represent all reasonable variations of casework currently performed by fire investigators. OSAC does not necessarily support or endorse (as best practices) all of the different steps and paths depicted in this process map.

Fire Investigation ProcessMap (Current Practice) Mar 14, 2023 PAGE15

5000 ? Reporting(1 of 2) Return to Overview

5002

Input

- Origin

- Possible cause

- Possible fire classification

- Data

- Analyzed data

- Resultsof analyses

- Findings

- Other information PAP

5030

Generate report (see Report Generation)

5004

Generate written

report?

5032

Conduct technical

review?

5038

Are all technical review

evaluation criteria

acceptable?

5036

Conduct technical

and/or supervisory

review PAP

GOTO

5110

Reporting (Page

2 of 2): Conduct

Admin Review

5034

Conduct administrative

review?

5012

Communicate findings

5010

Generate written

report now?

Report Generation

Reportsvary widely within the discipline of fire investigation; however, reportsgenerally may include elementssuch as:

- Intro/scope

- Data collection

- Data analysis

- Origin conclusion

- Cause conclusion

Additional report contents can also include the above, along with supplementary context

and/or subsections:

- Intro/scope

- Legal right of entry

- Methodology/Procedural narrative (e.g., reconstruction)

- NFPA921 guidance and recommended procedures

- Data collection:

- Event:

- Synopsisof event

- Scene:

- Diagrams

- Sketches

- Collages/photos

- Maps

- Non-Scene:

- Witnessinformation

- Public records

- Data analysis

- Origin

- Hypotheses

- Hypothesestesting

- Conclusion

- Cause

- Hypotheses

- Hypothesestesting

- Conclusion

- Responsibility:

- Fire spread analysis

- Size and scale

- Failureanalysis

- Consequence analysis(e.g., fatalitiesor injuries)

- Timeline

- Fire injuries and deaths

- Building construction

- Fire protection systems

- Classification

- References (e.g., citations, technical references, journal articles, recalls, etc.)

- Personnel

- Witnessesand contact info

- Signatures asrequired PAP

- Appendices(e.g., CVs, testimony lists, billingrates, activity reportsfrom various

personnel, etc.)

- Materialsreviewed (e.g., info provided by additional personnel)

- Additional reports/analyses/testimony reviewed (e.g., for evaluation for defense,

appeals, depositions, etc.)

GOTO

5114

Reporting

(Page 2 of 2):

Finalize report

5006

Hasa progress

report been requested ?

(See Progress Report)

5020

Generate progress

report

5016

Communicate

progress

5014

Generate written

progress

report?

5008

Communicate

findings?

Progressreport may contain elementssuch as:

- Any data collected

- Work completed

- Overall synopsisof what hasbeen done

so far on the case

No

Yes

No

Yes

No

Yes

No

Yes

No

Yes

No

Yes

No

Yes

FROM Variouslocations

in map

GOTO

5110

Reporting (Page

2 of 2): Conduct

Admin Review

Yes

GOTO

5100

Reporting (Page

2 of 2)

No

GOTO

5124

Reporting

(Page 2 of 2):

Archive

FROM

2040/3056/3250

4122/4320
OSACFire & Explosion Investigation Subcommittee

This process map provides a visual description and attempts to represent all reasonable variations of casework currently performed by fire investigators. OSAC does not necessarily support or endorse (as best practices) all of the different steps and paths depicted in this process map.

Fire Investigation ProcessMap (Current Practice) Mar 14, 2023 PAGE16

Return to Overview 5100 ? Reporting(2 of 2)

5114

Finalize report PAP

(e.g., reviewer

signatures)

5112

Are all

administrative review

evaluation criteria

acceptable?

5110

Conduct administrative

review PAP

5106

Isadditional data collection or analysis, or

evaluation of conclusion(s) required to

proceed?

5108

Update report as

needed PAP

5102

Consultation between

reviewer and

investigator

5104

Isan additional

reviewer needed?

5130

Resolve conflict(s), and

follow agency conflict

resolution policy (e.g.,

revise report, mediation,

consultation, elevate to management, conduct

further data analysis,

provide additional

documentation, etc.)

5116

Issuereport

5120

Discussion with

client/requester

5118

Additional questionsor

issuesfrom client or

requester?

5122

Update report as

needed

5124

Archive case record PAP

(e.g., to include all files,

data analysis, hypothesis

analysis, data,

documentation and

findingsetc. in

preparation for

generatinga possible

subsequent report)

STOP/End

Process

FROM 5038

5132

Based on knowledge, experience, and/or

agency policy select an option:

5134

Consult with one or more external

colleague(s), peer reviewer(s),

supervisor, or another type of

expert PAP

5136

Perform further data analysis

5144

Revisit area of origin

determination

5138

Seek additional data (Origin)

5140

Seek additional data (Cause)

RETURNTO

designated area(s) in map asneeded as

per consult

5150

Isadditional data

analysisrequired for

origin?

RETURNTO

3054

RETURNTO

2004

RETURNTO

2120

No

5142

Revisit existing data RETURNTO

2004

Yes

5146

Revisit cause determination RETURNTO

4006

Yes

No

No

No

Yes

Yes

FROM 5034

FROM 5034 FROM 5038

Yes

FROM 5010

RETURN TO

3004

RETURN TO

4020

5148

Proceed without additional

analysisor evaluation GOTO5110

GOTO5114

No

5149

Document technical review

(including any area(s) of

disagreement)

RETURN TO

5036
OSACFire & Explosion Investigation

Subcommittee

This process map provides a visual description and attempts to represent all reasonable variations of casework currently performed by fire investigators. OSAC

does not necessarily support or endorse (as best practices) all of the different steps and paths depicted in this process map.

Fire Investigation ProcessMap Mar 14, 2023 Page 17

(Current Practice)

Glossary of Termsand Definitions*

Consumed Heat Source5: An object that producesor radiatesheat that has

been consumed by the fire or explosion.

Ignition (Heat) Source (adapted from NFPA921)1: Asource of heat that

enablesthe processof initiating self-sustained combustion.

Failure Analysis1: Alogical, systematic examination of an item, component,

assembly, or structure and itsplace and function within a system, conducted

in order to identify and analyze the probability, causes, and consequencesof

potential and real failures.

BuildingSystems

3: Systemsof a building or facility such asthe electrical, HVAC,

security, life safety, lighting, utilities, telecom, and energy management; these may depend on each other to operate.

Area(s) of Origin1:Astructure, part of a structure, or general geographic

location within a fire scene, in which the?point of origin?of a fire or explosion

isreasonably believed to be located.

Geometry: The shape, form, and orientation of afuel that affectsitsignition

and burning characteristics.

First Fuel Ignited (aka Material First Ignited) - adapted from NFPA 9211: The

first fuel ignited isthat which first sustainscombustion beyond the ignition

source, e.g., the fuel that isfirst set on fire by the heat of ignition; to be meaningful, both a type of material and a form of material should be

identified.

Fire Patterns

1: The visible or measurable physical changes, or identifiable

shapes, formed by a fire effect or group of fire effects.

Fire Dynamics1: The detailed study of how chemistry, fire science, and the

engineering disciplinesof fluid mechanicsand heat transfer interact to

influence fire behavior.

Conductivity (adapted from NFPA921)1: The ability of a material to transfer

heat to another body by direct contact.

Alloying4: The formation of a substance from the combination of two or more metalsthrough mechanical, heat and masstransfer, and chemical

phenomena.

Field Testing: Testing of an ignition source, fuel(s), a component, or system at

the scene of a fire or explosion. Such testing of a component or system is

done in situ if disconnection or removal of the item would negate future

testing.

Fuel1: Amaterial that will maintain combustion under specified

environmental conditions.

Absorptivity: The fraction of incident radiation absorbed by a surface

Fault Tree Analysis

7: Alogic diagram based on the principle of multi-causality, which tracesall branchesof eventswhich could contribute to an accident or

failure.

Density

1: The massof a substance per unit volume, usually specified at a

standard temperature and pressure.

Kinetics: Rate of chemical reaction

Fire Scene Reconstruction1: The processof recreatingall or some of the

physical scene during fire scene analysisinvestigation or through the removal

of debrisand the placement of contentsor structural elementsin their

pre-fire positions.

Fire Testing: Teststo determine such thingsasignition characteristics, fire

growth and development, heat release, etc.

Computer Modeling: Mathematical model of a physical system intended to

approximate the dynamicsof the system.

Ignition Testing (adapted from NFPA921)1: Theprocessof testingthe

initiation of self-sustained combustion; includingthe ignition time, ignition

temperature, and ignition energy required for asubstance to burn.

Arcing1:High temperature luminouselectric discharging acrossa gap or

through a medium such ascharred insulation.

Exigent Circumstances

6: The principle established by the courtsthat the fire

department hasthe legal authority to enter a property to extinguish a fire

and determine the origin and cause of the fire (an act that isconsidered to be

a protection of the public welfare). Exigent circumstance isextended to a

reasonable timeframe to extinguish a fire and determine itsorigin and cause.

Inferred Heat Source (adapted from NFPA921)1: Asource of heat, which may

no longer be visible or present, that enablesthe processof initiating

self-sustained combustion (e.g., cigaretteor other heat source that may have

been consumed by the fire).

Orientation: The position and form of afuel source; thiscan influence the

response of a material to heat from an ignition source e.g., usinga solid block

of wood vs. kindling to start a campfire.

Pyrolysis

1: Aprocessin which material isdecomposed, or broken down, into

simpler molecular compoundsby the effectsof heat alone; pyrolysisoften

precedescombustion.

Suppression Activities

1: The sum of all the activities doneto extinguish a fire

Property Type and Scope: The occupancy and construction of aproperty.For

non-buildingsit meansthingslike vehicle or equipment type, land use,

structure use (tower, antenna, etc.)

Oxidants: Reactant that oxidizesor removeselectrons from other reactants

during a redox reaction.

Specific Heat: The quantity of heat required to raise the temperature of one

gram of a substance by one degree Celsius.

Fire Effects

1: Observable or measurable changesin or on a material or a

system that have occurred asa result of fire actions. Thermal Decomposition (adapted from NFPA 921)1:The chemical

decomposition of a surface or body caused by a rise in temperature.

Non-Scene Data: That which isrelevant to some aspect of the fire origin and

cause investigation but isnot contained within the actual fire scene.

Investigatorscollect ?non-scene data?and may use it to help establish the fire

or explosion timeline, identify an area of origin, document the growth and

spread of the fire, identify suppression effortswhich may have affected fire

growth and spread, provide context to another piece of data, or to establish

evidence of causation (e.g., lightning, intentional human acts).
OSACFire & Explosion Investigation

Subcommittee

This process map provides a visual description and attempts to represent all reasonable variations of casework currently performed by fire investigators. OSAC

does not necessarily support or endorse (as best practices) all of the different steps and paths depicted in this process map.

Fire Investigation ProcessMap Mar 14, 2023 Page 18

(Current Practice)

References

Return to Overview

1. NFPAGuide for Fire and Explosion Investigations: https://www.nfpa.org/codes-and-standards/all-codes-and-standards/list-of-codes-and-standards/detail?code=921

2. https://britannica.com/science/specific-heat

3. Adapted from:

https://www.archibus.net/ai/abizfiles/v23_help/archibus_help/user_en/Subsystems/webc/Content/asset_mngmt/background/bldg_system_define.htm#:~:text=

Building%20systems%20are%20the%20critical,on%20each%20other%20to%20operate.

4. Adapted from: https://www.sciencedirect.com/topics/materials-science/alloying and https://byjus.com/chemistry/alloy-meaning/

5. Adapted from: https://www.collinsdictionary.com/dictionary/english/heat-source

6. https://www.interfire.org/termoftheweek.asp?term=1384

7. https://www.icao.int/sam/documents/2014-adsafass/fault%20tree%20analysis%20and%20event%20tree%20analysis.pdf