Forensic Science unit 3.1 Flashcards
What is evidence?
Evidence is used at trials to prove or disprove certain facts that would tend to show whether something was true or not.
What does Locard’s Exchange Principle state?
With contact between two items, there will be an exchange.
What are the two areas evidence can be split into?
- Testimonial evidence
- Physical evidence
Define testimonial evidence.
Testimonial evidence would be any witnessed accounts of an incident or crime.
Define physical evidence.
Physical evidence refers to any material items that would be present on the crime scene or the victims.
What is trace evidence?
Trace evidence refers to physical evidence found at a crime scene in small but measurable amounts.
What type of evidence is described as being able to directly prove a fact?
Direct evidence
Give examples of direct evidence.
- Eyewitness Testimony
- Photograph
- Security Camera Footage
- Audio Recording
- Ballistics Tests
What is circumstantial evidence?
Circumstantial evidence is evidence that can help establish the circumstances of a crime but doesn’t directly link a defendant to the crime itself.
List examples of circumstantial evidence.
- Physical Evidence (fingerprints, DNA, blood, hair)
- Records (phone call, email records, medical records)
- Witness testimony
What is the difference between physical and biological evidence?
- Physical evidence: Non-living/inorganic (e.g., fingerprint, tire impressions)
- Biological evidence: Organic (e.g., DNA, bodily fluids)
What is class evidence?
Class evidence is a particular object but places the particular bit of evidence into a group of objects.
Give examples of class evidence.
- Fibers
- Paint
- Soil
- Glass
What is individual evidence?
Individual evidence narrows down the evidence to a single, individual source.
List examples of individual evidence.
- Trace Evidence
- DNA
- Fingerprints
- Some footwear impressions
- Bite Marks
- Bullets
Define trace evidence.
Trace evidence is small particles of material that are transferred between objects or people when they come into contact.
What are types of trace evidence materials?
- Fibers
- Primer Residue
- Hairs
- Paint
- Duct Tape
- Arson Debris
- Accelerants
- Unknown Substances (powders)
What are the parts of hair?
- Hair Follicle
- Hair Shaft
What is the purpose of hair analysis?
Hair analysis is used to test for drug use, heavy metals, some genetic disorders, and family links.
How does hair growth occur?
- Anagen: growth stage
- Catagen: transitional phase
- Telogen: resting phase
What distinguishes human hair from animal hair?
- Pattern of pigmentation
- Medullary index
- Cuticle type
What is a fiber?
A fiber is the smallest unit of a textile material that has a length many times greater than its diameter.
What are natural fibers commonly used in textiles?
- Cotton (plant fibers)
- Wool (animal fibers from sheep)
What are examples of synthetic fibers?
- Nylon
- Rayon
- Polyester
