Unit 1: Physical Evidence

Something that can be seen, heard, felt, smelled, etc and can be collected and analyzed in a crime lab

Relevant to the case

What someone says - A statement form police officers, witnesses, victims or suspects

Evidence that can be said to originate from a particular group only, NOT from a particular individual

Evidence that can be said to have originated from a single individual

A trial with no jury; only the judge will hear the evidence and decide the verdict

A trial where 12 people plus 1 alternate will hear the evidence and decide the verdict

A test to determine what a particular substance is; performed on the evidence sample

A test that analyzes both an evidence sample and a known sample then compares the results from the two to determine if they could have originated from the same source

A test using a known substance that should give a definite POSITIVE result

A test using a known substance that should give a NEGATIVE result

A test where a substance (usually plain water) is used; will check for contamination in the chemicals used to conduct the test

A sample collected from a victim, suspect or crime scene in connection with a crime

A collection of known samples from known sources analyzed with currently used, proven methods

The frequency of the occurence of an event

A sample collected from a known source with a proven chain of custody (such as a cheek swab from a suspect for DNA analysis)

Identifying a body fluid on evidence (such as blood, semen, or saliva) Identifying a white powder is a certain drug like heroin or methamphetamine Determining that a pile of glass recovered from the wound of a hit-and-run victim was auto glass

Comparing the DNA profile of semen recovered from a sexual assult victimto the DNA profile of the suspect Comparing the tire tread pattern left at the scene of a homiced to the tire tread pattern of the suspects vehicle Camparing the striations on a bulleet recovered from the body of a homiced victim to the striations on a bullet fired from the suspects gun

Hair (Looking at it under the microscope) Accelerant of a fire like gasoline Drug evidence, Fibers Auto, paint or glass Plant material (you could tell the species of plant, but not the individual plant)

Fingerprints, DNA, Footwear impressions Handwriting, Tire impressions Toolmarks (including striations on bullets or cartridge cases)

To prevent cross-contamination of the evidence sample with any material from the known sample

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