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ArsonArson

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What is fire?What is fire?

A study of arson needs to begin with an A study of arson needs to begin with an understanding of fire.understanding of fire.

Fire is a rapid oxidation of a material in the Fire is a rapid oxidation of a material in the chemical process of combustion. This process chemical process of combustion. This process also produces heat and light.also produces heat and light.

Fire is an exothermic reactionFire is an exothermic reaction.. The vapor of the fire is also The vapor of the fire is also

undergoing combustion.undergoing combustion.

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What is Arson?What is Arson?

Arson is the intentional setting of a fire to Arson is the intentional setting of a fire to a structure or wild land area. a structure or wild land area.

Arson is a complex crime and difficult to Arson is a complex crime and difficult to prove.prove.

The crime scene generally has extensive The crime scene generally has extensive destruction.destruction.

The crime scene technician has a limited The crime scene technician has a limited role. A trained arson investigator will role. A trained arson investigator will conduct a thorough investigation and conduct a thorough investigation and make the final determination.make the final determination.

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Occurrence and ProminenceOccurrence and Prominence

Arson is usually treated as a low Arson is usually treated as a low profile crime/occurrence and as a profile crime/occurrence and as a result the budget for it’s detection result the budget for it’s detection may be small.may be small.

However, arson can become high However, arson can become high profile if it involves civil profile if it involves civil rights/religious issues or becomes rights/religious issues or becomes serial in nature.serial in nature.

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Is it an Accident?Is it an Accident?

Accidental causes of fire include:Accidental causes of fire include: Cigarette smokingCigarette smoking Overheated electrical motorsOverheated electrical motors Improperly cleaned and regulated Improperly cleaned and regulated

heating systemsheating systems Faulty wiringFaulty wiring

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Is it an Accident?Is it an Accident?

To answer this To answer this question, the question, the investigator investigator must study the must study the fire in terms of fire in terms of the fire triangle.the fire triangle.

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The Fire TriangleThe Fire Triangle

Three requirements needed for Three requirements needed for combustion to be initiated and combustion to be initiated and sustained:sustained:

1.1. Fuel must be presentFuel must be present

2.2. Sufficient oxygen must be available to Sufficient oxygen must be available to combine with fuelcombine with fuel

3.3. Heat must be applied to initiate the Heat must be applied to initiate the combustion and sufficient heat must be combustion and sufficient heat must be generated to sustain the reactiongenerated to sustain the reaction

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The Fire TriangleThe Fire Triangle

If the fire is a case of arson, the arsonist If the fire is a case of arson, the arsonist will have manipulated one or more of the will have manipulated one or more of the components of the fire triangle. This components of the fire triangle. This manipulation must be proven in order to manipulation must be proven in order to state the fire is an arson.state the fire is an arson.

They may increase the fuel load by adding They may increase the fuel load by adding accelerant or flammable items.accelerant or flammable items.

More oxygen may be introduced by More oxygen may be introduced by opening windows or punching holes in opening windows or punching holes in walls or the ceiling.walls or the ceiling.

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Other Clues of an ArsonOther Clues of an Arson

– Multiple points of originMultiple points of origin– Strange odors Strange odors – Accelerant soaked rags will keep the fire low Accelerant soaked rags will keep the fire low

or localized, not traveling up as usualor localized, not traveling up as usual– Extensive regions of low burnExtensive regions of low burn– Faster and hotter fire than would be expected. Faster and hotter fire than would be expected. – Empty containers of accelerants, time delay Empty containers of accelerants, time delay

devices, and other items left by the devices, and other items left by the perpetratorperpetrator

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Ways the Fire beginsWays the Fire begins

Arsonists can start fires Arsonists can start fires

with a cigarette, matches, with a cigarette, matches,

firearms and ammunition, electrical firearms and ammunition, electrical

spark and a Molotov cocktail.spark and a Molotov cocktail.

The most common method The most common method is is with gasoline or with gasoline or kerosene or kerosene or some other some other flammable liquid.flammable liquid.

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Arson Arson InvestigationInvestigation

A criminologist needs to detect and A criminologist needs to detect and identify relevant chemical materials identify relevant chemical materials collected at the scene, reconstruct the collected at the scene, reconstruct the crime and identify detonating crime and identify detonating mechanisms.mechanisms.

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The search for relevant The search for relevant chemical materialschemical materials

Search for traces of flammable liquid Search for traces of flammable liquid residues may be aided by the use of a residues may be aided by the use of a highly sensitive portable vapor highly sensitive portable vapor detector or a “sniffer.”detector or a “sniffer.”

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Arson Dogs as “Sniffers”Arson Dogs as “Sniffers”Another approach is to use trained dogs Another approach is to use trained dogs

that have been conditioned to that have been conditioned to recognize the odor of hydrocarbon recognize the odor of hydrocarbon accelerants.accelerants.

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ArsonArson

Even dogs need Even dogs need protective gear.protective gear.

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Recreating the Crime:Recreating the Crime:Fire PatternsFire Patterns

Major objectives of a fire Major objectives of a fire examination is the recognition, examination is the recognition, identification, and analysis of identification, and analysis of fire patterns.fire patterns.

The circumstances of every fire The circumstances of every fire are different from every other are different from every other fire because of differences in fire because of differences in structures, fuel load, ignition structures, fuel load, ignition factors, airflow, ventilation, and factors, airflow, ventilation, and other variables.other variables.

Patterns can represent the Patterns can represent the history of the fire.history of the fire.

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What are the fire patterns?What are the fire patterns?

Common Fire Patterns include:Common Fire Patterns include: Classic V- ShapeClassic V- Shape Inverted ConeInverted Cone Protected AreaProtected Area Clean BurnClean Burn Run Down BurnRun Down Burn Ignitable Liquid Pour PatternIgnitable Liquid Pour Pattern

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Classic Classic V-ShapeV-Shape

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Inverted ConeInverted Cone

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Protected AreaProtected Area

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Clean BurnClean Burn

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Run Down BurnRun Down Burn

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Ignitable Ignitable Liquid Liquid Pour Pour PatternPattern

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Escalator Fire Escalator Fire Think about the fire pattern that Think about the fire pattern that

develops.develops.

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Dynamic of PatternsDynamic of Patterns

Recognition of fire patterns depends Recognition of fire patterns depends on the investigators understanding of on the investigators understanding of the development of fire, heat, and the development of fire, heat, and flame spread.flame spread.

Heat moves by convection, Heat moves by convection, conduction, and radiation.conduction, and radiation.

These produce the fire patterns and These produce the fire patterns and the nature of flame, heat, and smoke the nature of flame, heat, and smoke movement within a structure.movement within a structure.

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Arson InvestigationArson InvestigationThe investigator must also find the point of origin or The investigator must also find the point of origin or

where the fire began. The fire pattern should where the fire began. The fire pattern should indicate the origin.indicate the origin.

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Fire BehaviorFire Behavior

Normally a fire Normally a fire moves in an upward moves in an upward direction and so the direction and so the point of origin will point of origin will most likely be most likely be located closest to located closest to the lowest point that the lowest point that shows the most shows the most intense burning.intense burning.

The picture shows the point The picture shows the point of origin to be the of origin to be the

computer.computer.

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Fire BehaviorFire BehaviorInvestigators Investigators

follow the follow the

V-shaped V-shaped burn burn pattern pattern down to down to locate the locate the point of point of origin.origin.

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Fire BehaviorFire BehaviorThe depth of wood charring, or The depth of wood charring, or

alligatoring, is also a good indicator of alligatoring, is also a good indicator of point of origin.point of origin.

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Difficulties in the Difficulties in the InvestigationInvestigation

Evidence is destroyed Evidence is destroyed and transformedand transformed

Water, water, waterWater, water, water Destruction and Destruction and

alteration of structuresalteration of structures Perpetrator is usually Perpetrator is usually

long gonelong gone

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Arson SketchArson SketchAt a crime scene, nothing should be touched or At a crime scene, nothing should be touched or

moved before notes, sketches and moved before notes, sketches and photographs are made. The fire pattern photographs are made. The fire pattern should be included on the sketch.should be included on the sketch.

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Collecting EvidenceCollecting EvidenceTwo to three Two to three quarts of ash quarts of ash and soot debris and soot debris should be should be collected from collected from the point of the point of origin, and origin, and sealed in an sealed in an airtight airtight container, such container, such as paint can. as paint can. The airtight The airtight container will container will ensure that the ensure that the vapors do not vapors do not escape.escape.

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Temperature and Speed of the Temperature and Speed of the FireFire

The melting of The melting of materials such as materials such as metals and plastic can metals and plastic can be used to determine be used to determine the temperature of the the temperature of the fire.fire.

Cracking lines in Cracking lines in

windows are helpful in windows are helpful in determining the speed determining the speed

of the fire. Longer of the fire. Longer

cracks develop with cracks develop with slower fires.slower fires.

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Why?Why?

Arsonist cause fires at different Arsonist cause fires at different locations for different reasons.locations for different reasons.

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Motivation for arson includesMotivation for arson includes:: VandalismVandalism--both mischievous and both mischievous and

maliciousmalicious ExcitementExcitement--a thrill seeker, wants a thrill seeker, wants

attentionattention RevengeRevenge--retaliation for a personal or retaliation for a personal or

societal ‘injustice’societal ‘injustice’ Crime Concealment-Crime Concealment- to cover up a to cover up a

primary crime, such as a murderprimary crime, such as a murder ProfitProfit-- insurance money insurance money ExtremistExtremist-- beliefs on social issues, such beliefs on social issues, such

as abortion clinics or churches as abortion clinics or churches

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Finding the ArsonistFinding the ArsonistAn arson profiler will use An arson profiler will use

information from:information from:

the arson scenethe arson scene

any potential witnessesany potential witnesses

the types of accelerants usedthe types of accelerants used

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Famous FiresFamous FiresGreat Chicago FireGreat Chicago Fire

Speculated point of Speculated point of origin is a barn fireorigin is a barn fire

Davidian Branch Davidian Branch Compound Fire, Compound Fire, allegedly caused by allegedly caused by pyrotechnic tear gas.pyrotechnic tear gas.

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Famous FiresFamous FiresSpace Shuttle Challenger exploded Space Shuttle Challenger exploded

because of a fuel leak on the because of a fuel leak on the rocket rocket booster. booster.

Swiss Air Swiss Air Flight Flight crashed due to crashed due to

a fire caused a fire caused by faulty wiring. by faulty wiring.