Physical Evidence Flashcards
Physical Evidence
Define the following terms:
Tangible:
Something that can be seen, felt, heard, smelled, etc and can be collected and analyzed in a crime lab
Define the following terms:
Probative:
Relevant to the case
Define the following terms:
Testimonial evidence:
What someone says such as statements from police officers, witnesses, victims or suspects
Define the following terms:
Class evidence:
Evidence that can be said to originate from a particular group only, NOT from a particular individual
Define the following terms:
Individual evidence:
Evidence that can be said to have originated from a single individual
Define the following terms:
Bench trial:
A trial with no jury; only the judge will hear the evidence and decide the verdict
Define the following terms:
Jury trial:
A trial where 12 people plus 1 alternate will hear the evidence and decide the verdict
Define the following terms:
Identification test:
A test to determine what a particular substance is; performed on the evidence sample
Define the following terms:
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
Define the following terms:
Positive control:
A test using a known substance that should give a definite POSITIVE result
Define the following terms:
Negative control:
A test using a known substance that should give a definite NEGATIVE result
Define the following terms:
Database:
A collection of known samples from known sources analyzed with currently used, proven methods
Define the following terms:
Manipulation blank:
A test where a substance (usually plain water) is used; will check for contamination in the chemicals used to conduct the test
Define the following terms:
Evidence sample:
A sample collected from a victim, suspect or crime scene in connection with a crime
Define the following terms:
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)
Define the following terms:
Probability:
The frequency of the occurrence of an event
What are three 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 piece of glass recovered from the wounds of a hit and run victim was auto glass
Give three examples of comparison tests:
- Comparing the DNA profile of semen recovered from a sexual assault victim to the DNA profile of the suspect
- Comparing the tire tread pattern left at the scene of a homicide to the tire tread pattern of the suspect’s vehicle
- Comparing the striations on a bullet recovered from the body of a homicide victim to the striations on a bullet fired from the suspect’s gun
Individual or class evidence: Hair (looking at it under the microscope)
Class Evidence
Individual or class evidence: Drug evidence
Class Evidence
Individual or Class evidence: Plant material (you could tell the species of plant, but not the individual plant)
Class Evidence
Individual or Class evidence: Accelerant of a fire like gasoline
Class Evidence
Individual or Class evidence: Fibers
Class Evidence
Individual or Class evidence: Auto paint or glass
Class Evidence
Individual or Class evidence: Fingerprints
Individual Evidence
Individual or Class evidence: DNA
Individual Evidence
Individual or Class evidence: Footwear impressions
Individual Evidence
Individual or Class evidence: Handwriting
Individual Evidence
Individual or Class evidence: Tire impressions
Individual Evidence
Individual or Class evidence: Toolmarks (including striations on bullets or cartridge cases)
Individual Evidence
Why is it important to always process evidence samples 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!!!!
