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Fire Investigation

Published on Nov 21, 2015

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PRESENTATION OUTLINE

FIRE INVESTIGATION

By: Victoria Strauss

CHEMISTRY OF FIRE

  • Fire includes the combination of oxygen with other substances
  • For a fire to be started, the ignition temperature must be reached
  • The heat of combustion is the heat evolved when a substance burns

CHEMISTRY OF FIRE

  • Another factor of fire is the rate or speed at which the oxidation takes place
  • Flash point: a liquid burns when the temperature is high enough to vaporize it
  • Pyrolysis: solid is hot enough to decompose into gaseous products
  • Glowing combustion: burning at the fuel-air interface

CHEMISTRY OF FIRE

  • Spontaneous combustion: result of a natural heat producing process in poorly ventilated containers or areas
  • Use the following to initiate and sustain combustion: a fuel, oxygen and heat

SEARCHING THE FIRE SCENE

  • Examine for signs of arson
  • Most arsons started with petroleum-based accelerants
  • Must focus on finding the fire's origin
  • Fire has a tendency to move in an upward direction ; origin will most likely be the lowest point

COLLECTION/PRESERVATION OF ARSON EVIDENCE

  • Ash, soot, and porous materials should be collected and stored in airtight containers
  • Flammable liquid residues are able to be located with a vapor detector
  • Control specimens should be collected
  • Search for ignitors should be conducted

ANALYSIS OF FLAMMABLE RESIDUES

  • Gas chromatograph is used for detecting and characterizing flammable residues
  • It separates the hydrocarbon components and produces a pattern of a particular product
  • Arsons initiated by petroleum distillates
  • Comparisons of crime scene patterns to known flammable liquid patterns allows an analyst to identify the accelerant

PICTURE CITATIONS

  • IRE . Photography. Encyclopædia Britannica ImageQuest. Web. 27 Mar 2015.
  • Fire scene investigation. Photography. Encyclopædia Britannica ImageQuest. Web. 27 Mar 2015.
  • Investigators from the Bureau of Alcohol, Tobacco, and Firearms, BATF, or ATF, examine the scene of a large fire that destroyed two multi-story buildings. They are investigating from a crane suspended basket and on the building itself.. Photograph. Encyclopædia Britannica ImageQuest. Web. 27 Mar 2015.
  • Fire scene remains. Photography. Encyclopædia Britannica ImageQuest. Web. 27 Mar 2015.
  • Photographing evidence. Photography. Encyclopædia Britannica ImageQuest. Web. 27 Mar 2015.