Hair Evidence
What are the three main parts of a hair?
Answer: Cuticle, Cortex, Medulla
Are fibers class or individual evidence?
Answer: Class evidence
Name the three types of impressions.
Answer: Patent, Latent, Plastic
This burn pattern often points investigators toward the fire’s point of origin.”
Answer: What is a V‑pattern? OR burn patterns
Bite marks are a type of __________ evidence.
Answer: Impression evidence
Which phase of hair growth is active?
Answer: Anagen phase
Give one example of a natural fiber and one of a synthetic fiber.
Answer: Natural – cotton, wool; Synthetic – nylon, polyester
Which type of impression is visible without extra processing?
Answer: Patent impression
These chemicals—like gasoline or kerosene—are commonly detected using GC‑MS in arson investigations.”
Answer: What are petroleum‑based accelerants?
Which bite mark type means significant pressure was applied?
Answer: Clear impression
How can you tell the difference between human and animal hair under a microscope?
Answer: Animal hair has patterned medulla; human hair medulla is thinner/fragmented.
Why are fibers considered trace evidence?
Answer: Because they are often transferred between people and objects in small amounts.
A shoe print is found in mud. What type of impression is this?
Answer: Plastic impression
This type of laboratory test detects volatile vapors released from burned materials.”
Answer: What is headspace analysis?
Which bite mark type means medium pressure was applied?
Answer: Obvious impression
Why is hair usually class evidence?
Answer: Because without the follicle (DNA), it cannot be linked to one individual.
Investigators test a fiber and find it melts easily. Is it more likely natural or synthetic?
Answer: Synthetic fiber
Why would investigators make a cast of an impression?
Answer: To preserve it for analysis and comparison.
Finding more than one of these strongly suggests a fire was intentionally set.”
Answer: What are multiple points of origin?
Why are bite marks usually considered class evidence?
Answer: Because many people may share similar dental patterns.
Investigators find hair with a follicle (root) attached. Explain why this may now be considered individual evidence.
Answer: The follicle allows DNA testing, making it unique to a person.
A red fiber is found on a suspect’s clothing that matches carpet fibers from a crime scene. How does this help investigators?
Answer: It links the suspect to the scene through class evidence transfer.
Explain how impressions can be both class and individual evidence.
Answer: Class = shoe brand/size, Individual = unique wear patterns or damage.
Investigators collect this type of physical material to test for accelerant residues after a fire.”
Answer: What is fire debris?
Explain how a bite mark can sometimes become individual evidence.
Answer: If the person has unique dental features (crooked, missing, or chipped teeth).