Hair Today, Gone Tomorrow
This type of transfer occurs when a fiber moves directly from a victim's shirt onto a suspect's jacket.
What is a direct transfer?
The three major parts of the hair shaft from outside to inside.
What is Cuticle → Cortex → Medulla ?
A hair which has a medullary index of 0.20 would be classified as this type of hair.
What is human?
Wool & silk both belong to these categories of fiber.
What is natural/animal fibers?
This type of transfer occurs if a hair moves from a victim to a suspect's clothing and then from the suspect's clothing to a car seat.
What is a secondary transfer?
This hair layer is made of overlapping scales and forms the outermost layer of the hair.
What is the cuticle?
A hair which has a medullary index of 0.58 would be classified as this type of hair.
What is animal?
What is synthetic/polymer fiber.
This type of container would be used for trace evidence like hair.
What is a paper bindle?
A scientist observes an inner core that varies in thickness and may be continuous, broken, or absent. What structure is being examined?
What is the medulla?
A type of hair that is thick, coarse & may contain a double medulla.
What is the face?
Cotton belongs to each of these categories.
What is natural/plant/seed fiber?
An investigator finds four hairs on a victim's shirt. Three hairs are loose, while one is firmly attached to the fabric. Describe how the investigator should document and collect the four hairs.
Photograph & document the hairs in their original locations. Loose hairs should be collected with clean forceps & placed in an appropriate container. The firmly attached hair should remain attached to the shirt, & the clothing should be packaged with the hair intact.
A scientist is examining this portion of a hair that contains most of the pigment & provides much of the hair's strength.
What is the cortex?
This type of hair is oval or triangular & shows buckling.
What is pubic?
Name four observations a scientist might record during a flame test.
What is melting/shrinking, flame characteristics, burn rate, odor, or residue/ash?
A hair recovered from a crime scene has no root attached, but investigators still want to obtain DNA information from it. Which type of DNA could potentially be analyzed, where would it come from, and what type of information could it provide?
Mitochondrial DNA can potentially be obtained from the hair shaft. It can provide information about maternal relationships, but it cannot be used to identify one specific individual.
A forensic scientist wants to compare two hairs. Give four microscopic characteristics that could be examined to determine whether the hairs are similar.
Cuticle/scale pattern, medulla characteristics, medullary index, pigment distribution, cross-sectional shape.
FINAL JEOPARDY - A scientist finds a hair with a medullary index of 0.28, an oval/triangular cross section, and a double medulla. What can the scientist reasonably conclude about the hair, and what additional characteristic could strengthen the comparison?
It is more consistent with human hair because the medullary index is below 0.33. The characteristics are also consistent with beard hair. Additional characteristics such as cuticle pattern, pigment distribution, or other microscopic features could strengthen the comparison.
A forensic scientist examines an unknown fiber and determines that it is natural, came from a plant, and originated from the stem of the plant. Name three possible fibers that could be the unknown sample.
What is flax, jute or hemp?