Forensics chapter 4 arson vocab
What are the motives for arson
Financial gain, revenge, excitement, vanity, crime concealment, and vandalism
Endothermic reaction
Absorbs energy from its surroundings, sometime heat
Accelerant
Any material used to start or maintain a fire
Passive or direct? Gas chromatography
Both
Passive or direct? Heat at bottom
Both
Passive or direct? Held in an air tight container such as a paint can
Both
Natural
Caused by an act of nature such as a lightening strike or intense heat
Arc damage
Caused by electricity jumping out of a circuit, there's no proof that it was arson
Oxidation
Chemical reaction that involves a loss of electrons or a gain of a oxygen molecule
Exothermic reaction
Chemical reaction that releases heat
Classic v
Common pattern of fire. Does not indicate an accelerant was used. Shaped like a V, with point of origin at bottom
Pyrolysis
Decomposition of organic matter by heat
Passive or direct? Needs a lot of debris
Direct
Passive or direct? Not very sensitive
Direct
Passive or direct? Uses syringe to draw vapors out
Direct
Passive or direct? Very fast
Direct
What makes up the fire tetrahedron
Heat Oxygen Fuel Chain reaction
Molotov cocktail
Is a homemade firebomb made with glass bottle, fuel, and a wick. Will possibly leave glass fragments
Flash point
Minimum temperature at which liquid fuel can vaporize
Does a fire investigator need a warrant why or why not
No because, by the time they got one the evidence would be gone since vapors would escape
Accidental
Not intentional for example faulty electrical wiring
Deliberate
On purpose, however, not all deliberate fires are considered arson. For example, a campfire getting out of control.
Passive or direct? Only uses a little debris
Passive
Passive or direct? Takes a long time
Passive
Passive or direct? Vapors are absorbed on a charcoal strip
Passive
Passive or direct? Very sensitive
Passive
What must a fire investigator look for first at a scene?
Point of origin
Inverted cone
Point of origin is the whole bottom of the cone good indicator that an Exceller it was use not normal fire pattern, however not absolute
Pool or plant
Puddle burn mark, someone poured an accelerant in a puddle. It was arson.
Alligatoring
Seen on wood that has burned very hot, often an indicator of an accelerant, however not absolute, can help show the point of origin
Spalling
Splatters or speckles on brick or concrete. Good indicator of accelerant and arson, fire had to be extremely hot
Explain file in reference to the fire tetrahedron
The accelerant burns first. Soon, other nearby materials, such as wood or paper, ignite and become fuel for the continuation of the fire
Describe chain reaction in reference to the fire tetrahedron
The fire itself usually releases enough heat to keep he fire burning. The fire will continue to burn until all the oxygen or fuel is used or removed
Vaporization
The process where liquid changes to gas
Streamers
Trails of burn patterns, someone poured an accelerant on the ground in a trail. it was arson.
Undetermined
Unidentifiable
Which way does a fire always burn
Up
Describe heat in reference to the fire tetrahedron
When a heat source is present, the temperature of a substance rises
Point of origin
Where the fire started
How is evidence collected at the scene
•investigators collect 3-4L of ash and debris from the point of origin •collect anything that could have traces of an accelerant (look in cracks in the floor and upholstery) •use sniffers to detect molecuales and particles in the air that hold traces of an accelerant •may use arson dogs
