Fire and Arson InvestigationFire and Arson Investigation

Fire Patterns associated Fire Patterns associated with Ignitable Liquid with Ignitable Liquid

AccelerantsAccelerants

By

Bob Corrywww.sceneinvestigator.com

“One of the major

objectivesof a fire scene examination

is the recognition,

identification and analysis of fire patterns.”

NFPA 921 (2004)4.1

Success in Success in RecognizinRecognizin

g Arson g Arson begins with begins with recognizing recognizing

possible possible Arson Fire Arson Fire PatternsPatterns

Success in Success in RecognizinRecognizin

g Arson g Arson begins with begins with recognizing recognizing

possible possible Arson Fire Arson Fire PatternsPatterns

NFPA 921 on Fire PatternsNFPA 921 on Fire PatternsNFPA 921 on Fire PatternsNFPA 921 on Fire Patterns Holes in the floor may be caused by glowing combustion, radiation

or an ignitable liquid. 6.2.3.1

There is no justification that the appearance of large, curved blisters is an exclusive indicator of an accelerated fire. 6.5.5

The presence or absence of spalling should not, in and of itself, be construed as an indicator of the presence or absence of a liquid fuel accelerant. 6.6.2.3

The collapse of springs cannot be used to indicate exposure to a specific type of heat source or ignition such as smoldering ignition or the presence of an ignitable liquid. 6.14

Inverted cone patterns have been interpreted as proof of flammable liquid fires, but any fuel source that produced flame zones that do not become vertically restricted can produce inverted cone patterns. 6.17.3.1.2

First!First!

Search forSearch for Odd VariationsOdd Variations inin Fire Fire PatternsPatterns

First!First!

Search forSearch for Odd VariationsOdd Variations inin Fire Fire PatternsPatterns

Unusual “localized”Unusual “localized” wall patternwall pattern

Unusual floor Unusual floor burn patternburn pattern

Unusual, Unusual, localizedlocalized damagedamage

to the bedto the bed

Witnesses Reported:

Odor of Gasoline!

A low pressure wave!

Furniture moved before fire!

Symptoms of Ignitable Liquid Use Symptoms of Ignitable Liquid Use ((Possible indicators of an accelerated fire)Possible indicators of an accelerated fire)

Symptoms of Ignitable Liquid Use Symptoms of Ignitable Liquid Use ((Possible indicators of an accelerated fire)Possible indicators of an accelerated fire)

Burn injuries Burn injuries

to the to the

hands, face, legshands, face, legs

or hair of a suspect/witness.or hair of a suspect/witness.

Afternoon ProgramAfternoon ProgramAfternoon ProgramAfternoon ProgramUnnatural Fire SpreadUnnatural Fire Spread

(downward, unusually fast, etc.)(downward, unusually fast, etc.)

One gallon One gallon of gasolineof gasoline

was was poured poured here!here!

““Unnatural” Fire DamageUnnatural” Fire Damage

Bright yellow/orange flames Bright yellow/orange flames accompanied by black smoke.accompanied by black smoke.

Intense localized rusting/warping, Intense localized rusting/warping, especially to the undersides of especially to the undersides of metal objects within the patternmetal objects within the pattern

Intense localized Intense localized rusting/warping, rusting/warping,

especially to the undersides of especially to the undersides of metal objects metal objects

within the patternwithin the pattern

Structural damage Structural damage inconsistent inconsistent

with fire loadingwith fire loading

Intermixed light, Intermixed light, medium & heavy medium & heavy

burn patterns burn patterns within within

the overall patternthe overall pattern

““Rainbow-colored” Rainbow-colored” sheen sheen

on the surfaceon the surface of of

suppression water suppression water over the over the

pour area.pour area.

Accelerant containers Accelerant containers in or near the scene.in or near the scene.

Increased Increased burn damage burn damage

pattern pattern at the at the

bottombottom of of boxes, boxes,

furniture furniture legs, etc.legs, etc.

Pool shaped, intermixed, Pool shaped, intermixed, mottled black and brown mottled black and brown

staining staining on concrete on concrete

together with a tendencytogether with a tendency to repel water.to repel water.

““Ghost marks” Ghost marks” between seams between seams

of floor tiles of floor tiles within the pour area.within the pour area.

Localized “clean burn”area Localized “clean burn”area on a wall or appliance on a wall or appliance

above a pattern above a pattern where intense heat where intense heat

burned away burned away soot deposits.soot deposits.

““Inverted Cone” Inverted Cone” fire patternfire pattern

Search for the Search for the soot plume!soot plume!

Key Properties of Common Ignitable Key Properties of Common Ignitable LiquidsLiquids Behave like any liquid before ignition.Behave like any liquid before ignition. Most float on water, are immiscible, rainbowMost float on water, are immiscible, rainbow Form explosive vapors at room temperaturesForm explosive vapors at room temperatures Vapors are heavier than airVapors are heavier than air Readily absorbedReadily absorbed Powerful solventsPowerful solvents Don’t spontaneously igniteDon’t spontaneously ignite Explosive Limits/Ignition TemperatureExplosive Limits/Ignition Temperature Sampling the accelerant fire patternSampling the accelerant fire pattern

Related Physical EvidenceRelated Physical EvidenceRelated Physical EvidenceRelated Physical Evidence

The Accelerant ContainerThe Accelerant Container Other instrumentalities (i.e. ignition Other instrumentalities (i.e. ignition

device)device) Changing the arrangement of Changing the arrangement of

combustibles to increase fire combustibles to increase fire loadingloading

Propping open doors & windowsPropping open doors & windows The ignition deviceThe ignition device Explosion/Deflagration?Explosion/Deflagration? Burn patterns and the burned Burn patterns and the burned

“perp”“perp”

For Specialized Training:

www.interfire.org

For Specialized Training:

www.interfire.org

Accelerant Detection K-9 Teams are Accelerant Detection K-9 Teams are very very importantimportant especially especially in large loss fires.in large loss fires.

Accelerant Detection K-9 Teams are Accelerant Detection K-9 Teams are very very importantimportant especially especially in large loss fires.in large loss fires.

A Pocket Guide toA Pocket Guide toAccelerant Evidence Collection, Accelerant Evidence Collection,

22ndnd Edition Edition

Cited as a reference in Cited as a reference in all editions of NFPA all editions of NFPA 921, Kirk’s Fire 921, Kirk’s Fire Investigation 5th Investigation 5th Edition, interFIRE VREdition, interFIRE VR

Go to www.maiaai.org for more information