Arson and Fire Investigation

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Arson and Fire Investigation
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Summary

• Fire What is fire?
• Collecting evidence
• Analyzing evidence

• Explosives What are they?
• Collecting evidence
• Analyzing evidence

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Fire

• Arson - The crime of maliciously, voluntarily,
  and willfully setting fire to the building,
  buildings, or other property of another or of
  burning one's own property for an improper
  purpose, as to collect insurance.

Arson The crime of starting an illegal fire.
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Fire

• Fire rapid oxidation with evolution of heat
  and light.

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Fire
Four components of fire

• Fuel
• Heat
• Oxygen
• Uninhibited chemical chain reaction

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Fire
Four components of fire

• Fuel can be solid, liquid or gas
• Fuel can only consumed in the vapor state
• Therefore, solids and liquids must first be
  vaporized

• Burning takes place at the surface of solids and
  liquids.

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Fire
Four components of fire

• Heat Temperature
• Oxygen found in air can be used up in closed in
  spaces.

• Chemical Chain Reaction must
• The oxidation reaction (burning) must produce
  enough heat to maintain burning
• The fuel mass must be vaporized and drawn up into
  the flame.

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Fire
Fire Investigation

• First the point of origin is determined
• Where the fires starts
• Usually contains the most damage.

Once point of origin is determined, the cause of
the fire is determined.
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Fire gt Investigation

• Cause of Fire

• Undetermined
• Intentional

• Natural
• Accidental

Who investigates the fire?
Often, the Fire Department will have an
investigative team to determine the cause/origin
of a fire. (major events ATF)
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Fire gt Investigation
What evidence can be collected?

• Paper/Trash not much evidence
• Accelerant rapid start
• Chemical device (road flares, propellant)
• Electronic device for delayed ignition

Unburned portions of chemical and electronic
devices may be left behind.
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Fire gt Collection
Collection of Evidence

• Even in a large fire, accelerant residues of
  flammable liquids may be left behind.

• Common gasoline, kerosene, fuel oil
• Rarer alcohol, paint thinner

Unusual burn pattern may suggest use of liquid
accelerant.
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Fire gt Collection
Collection of Evidence

• Accelerant remains can be detected by tracing the
  point of origin or canine use.

Object containing accelerant must be packaged in
air tight container.
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Fire gt Collection

• Containers for Evidence

• Metal cans airtight, but old cans might rust

• Glass Jars rubber or glued liners may interfere
  with results.

• Special airtight plastic evidence bags must be
  properly sealed

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Fire gt Collection
Collection of Evidence

• Along with sample from point of origin, a control
  sample should be collected. (material from a
  different room/location)

• Carpet fibers (synthetics) may be petroleum
  based.

• Obviously, evidence collection documented with
  photos, sketches, etc.

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Fire gt Analysis
Analysis of Accelerants

• Gas Chromatography separates components and Mass
  Spectrometry identifies the components.