Unit 1: Physical Evidence Flashcards
Tangible
Something that can be seen, heard, felt, smelled, etc and can be collected and analyzed in a crime lab
Probative
Relevant to the case
Testimonial Evidence
What someone says - A statement form police officers, witnesses, victims or suspects
Class Evidence
Evidence that can be said to originate from a particular group only, NOT from a particular individual
Individual Evidence
Evidence that can be said to have originated from a single individual
Bench Trial
A trial with no jury; only the judge will hear the evidence and decide the verdict
Jury Trial
A trial where 12 people plus 1 alternate will hear the evidence and decide the verdict
Identification Test
A test to determine what a particular substance is; performed on the evidence sample
Comparison Test
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
Positive Control
A test using a known substance that should give a definite POSITIVE result
Negative Control
A test using a known substance that should give a NEGATIVE result
Manipulation Bank
A test where a substance (usually plain water) is used; will check for contamination in the chemicals used to conduct the test
Evidence Sample
A sample collected from a victim, suspect or crime scene in connection with a crime
Database
A collection of known samples from known sources analyzed with currently used, proven methods
Probability
The frequency of the occurence of an event
Known Sample
A sample collected from a known source with a proven chain of custody (such as a cheek swab from a suspect for DNA analysis)
What are 3 types of identification tests?
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
Give 3 examples of comparison tests.
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
What are 3 examples of class evidence?
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)
What are 3 examples of individual evidence?
Fingerprints, DNA, Footwear impressions
Handwriting, Tire impressions
Toolmarks (including striations on bullets or cartridge cases)
Why is it important to always process evidence smaples PRIOR to processing known standards?
To prevent cross-contamination of the evidence sample with any material from the known sample
Which type of evidence is most common at crime scenes? Class or Individual?
Class
