FIRE INVESTIGATION

CHEMISTRY OF FIRE

• Solids burn when there is enough heat to decompose it into gaseous products and liquids burn when the temperature is hot enough to vaporize it
• One factor needed to explain fire is the rate or speed at which the oxidation reaction takes place

SEARCHING THE FIRE SCENE

• As soon as the fire has become extinguished the arson investigator must start to look for signs of arson
• Most arsons are started with petroleum-based accelerants
• Most important piece of fire scene investigation is finding fires origin

COLLECTION/PRESERVATION OF ARSON EVIDENCE

• Ash and soot found at the origin of the fire as well as porous materials should be collected and stored in air tight containers
• Liquid residues may be found with a vapor detector
• Control specimens must be collected as well as ignitors.

ANALYSIS OF FLAMMABLE RESIDUES

• Using a gas chronograph separates the hydrocarbon components and produces a chromatographic pattern characteristic of a particular petroleum product.
• The gas chromatograph is the most reliable and sensitive instrument for detecting and characterizing flammable residues

WORKS CITED

• Jason Stone / NHPA / Photoshot / Universal Images Group
• Tom Williams / Roll Call Photos Inc. / Newscom / Universal Images Group
• BJORN SVENSSON / SCIENCE PHOTO LIBRARY / Universal Images Group
• Larry Michael / Nature Picture Library / Universal Images Group