Unit 2: Arson and Explosives
Components necessary for a fire?
Oxygen, heat and fuel
Burn indicators that have evidentiary value? (proof arson has occurred)
Evidence of arson = Some telltale signs of arson are evidence of separate and unconnected fires, use of “streamers” to spread the fire from one area to another and evidence of severe burning found on the floor due to a flammable liquid.
Evidence of point of origin?
Probable origin= the lowest point is the most intense burning (fire moves upward) .Characteristics= V-pattern, spalling(blistering) of concrete, Beginning of the fire trail, Accelerant? …Accelerant flow to the lowest point and Gathering/piling of fuel materials.
Canines → physiological advantage over humans?
Canines have more olfactory nerves than humans, so they are able to smell more better than us!
Methods for removing/analyzing accelerant residue?
Techniques used to remove accelerants from debris = Heated headspace - Closed container • Samples headspace over residue
Purge and trap - Closed container • Uses charcoal strip or charcoal tube to trap accelerants • Uses vacuum or positive pressure with inert gas to force accelerant vapour through the charcoal trap.
Preliminary screening for explosions? Dogs!
Preliminary field tests may be used for screening the debris on the explosion site. They include commercially available explosive vapor detectors and chemical color tests.
Primary vs. secondary explosives? Low vs. high explosives?
Primary explosives detonate by ignition from some source such as flame, spark, impact, or other means that will produce heat of sufficient magnitude.
Secondary explosives require a detonator and, in some cases, a supplementary booster.
High Explosive Types: Initiating (or primary explosives) Non-initiating. Secondary or base explosives) Includes Dynamite, TNT or PETN, and ANFOs.
Low explosives Definition— chemicals that oxidize rapidly, producing heat, light, and a pressure wave. will explode only when confined.
Griess Test→ what does it test for?
The Griess test detects the presence of nitrates and nitrates.