Forensic Quiz 6 Flashcards
Fire
the evolution of energy in the form of light, heat and smoke as a result of combustion
combustion
a type of chemical reaction where by a fuel reacts with oxygen to release energy(exothermic reaction-releases heat)
Compounds Needed for Fire
1.Oxygen
2.Fuel Source
3.Heat Source(activation energy)
Examples of Extinguishing Fire
1.Water-removes/takes out heat source
2.Fire blanket-remove oxygen
3.Foam Extinguishers-suffocates,removes oxygen
4.Co2 extinguishers-removes oxygen
Incendiary Fire
a fire that is willfully and intentionally set (crime=arson)
To see how fire started
Looking for ignitable liquid(accelerant)=the fuel that is used to start a fire that otherwise could not be easily started
Fire started
1.Liquid that requires low activation energy so it can be readily combusted
2.generally would draw attention to the purchase ex.gasoline-most common,charcoal lighter fluid, paint thinner,alcohol
Investigation of a Fire (A)
A.Causes
1.Natural
2.Accidental
3.Deliberate
4.Undetermined
Investigation of Fire (B)
B.Ways for fire to be arson
1.presence of molotov cocktail
2.Fire Trail
3.Prescence of multiple points of origin(where fire started)
Investigation of Fire (C)
C.Motives for committing Crime
1.revenge
2.fraud-insurance money
3.Conceal a crime
4.Pyromania(affinity towards fire)
Burn Patterns
-visual/measurable physical effects that remain after fire
-tells where fire originates
-fingerprints of fire scene
-come in all different shapes/sizes
-72 different types of burns patterns
-Test to see residue ignitable liquid-intentional/arson (gaschromotography)
Explosions
A.Types
1.deflagration
2.detonation
deflagration
1.low explosives that produces escaping gases of velocities less that the speed of sound (343mls)
detonation
high explosives that produce escaping gases of velocities greater than the speed of sand
bomb seat
point of origin or location of bomb
-find remnant/pieces of bomb
Griess Test
Test for explosive residues(postive/+ means presence of nitrates/nitrites(N-O Bonds)
Questioned Document
any written or printed communication between individuals whose source or authencitis is in doubt
-does not have to be written paper/pen
Best Evidence Rule
original document
Questioned Document Examiner
compares unknown hadwriting typewriting and other documentary evidence with known standards to establish origin and authenticity of unknown materials
Graphologist
someone claims to discern personality characteristics based on someones handwriting
Handwriting goes through natural changes due to..
1.age-maturity
-illness/discease-arthiritues/parkinson
-drugs/alcohol
-trauma/injury to hand
2.Depends on circumstances-mental state
3.Paper/stationary-notebooks vs a napkin
4.Writing instrument
Becomes internalized when..
looking at substance of writing not look of it
Handwriting Comparison
1.Presence of sufficient unique characteristics in the writing specimen(writing exemplar/sample- can be requested or non requested)
Characteristics Used for Handwriting Comparision
1.no two people have identical handwriting
2.natural variation ina persons writing(mental/physcial state)
3.no single writing characteristic that is so unique by itself that will individualize that handwriting
4.no set number of characteristics that must be present for examiner to identify the author of questioned document
Forgery
1.Trace
2.Practice
3.Scribble
Types of Alteration
1.Erasure-chemical(bleaching agent) or mechanical
-analyze paper with UV light
2.Obliteration(destroy)-ex a will
3.Addition(add something to original document/change context)
