Unit 3: Evidence Collection

Indirect Evidence

Implies a fact, but not seen or heard first hand.

Value of Indirect Evidence

1. Generally more reliable than testimonial

2. Can prove that a crime has been committed

3. Can corroborate or refute testimony

4. Can link a suspect with a victim or with a crime scene

5. Can establish the identity of persons associated with a crime

6. Can allow reconstruction of events of a crime

Locard Exchange Principle

When a person comes in contact with an object or another person, a cross-transfer of physical material can occur.

Physical Evidence

human generated; Impressions (footprints, tire marks, shoe prints, fingerprints), Glass, Fibers

Chemical

synthetic substances; Paint, Fire debris (flammable liquids aka accelerants), Chemicals (Drugs, explosives)

Biological

Once Living; Bodily fluids, Hair, Plants, Natural fibers

Class Evidence

common to a group of objects or persons

Individual Evidence

can be identified with a particular person or a single source