Hair, Fibers, and Paint Study Guide
1. What are the layers to the hair shaft?
2. Describe the purpose for each layer of the hair shaft. How do we use them
for Forensics?
Cuticle-outermost layer, scales/cells (prevent damage to inner structure)
Cortex-middle, strength, color (melanin), and texture
Medulla-identification, color (medulla disappears when hair is gray)
3. What are the four types of medulla?
Draw a picture of each
4. How are the medullas different by race?
Asian hair holds the speed record for growth with 1.3 cm a month. On the other hand, it has lower density
than any of the other ethnic groups. The way its follicle is implanted causes the hair to grow straight,
perpendicular to the scalp.
African hair, generally black hair, is the slowest growing of all, at less than 0.9 cm a month. On the other
hand it is slightly more dense than Asian hair and grows almost parallel to the scalp, twisting around itself as
it grows
As far as rate of growth is concerned, Caucasian hair comes between the other two at 1.2 cm a month, but
it has the highest density of all. It grows at an oblique angle to the scalp and is slightly curved.
http://www.hair-science.com/_int/_en/topic/topic_sousrub.aspx?tc=roothair-science%5Eliving-and-reliving%5Eelsewhere-in-world&cur=elsewherein-world
5. What are the three stages for hair? Describe each stage.
6. How do we determine the sex from hair?
If hair is pulled out by the root, as in some violent struggles, it will contain root pulp which is a
good source of nuclear DNA (nDNA), the type of DNA most often used in forensics. The hair
shaft does not contain nDNA, so the 100-150 strands of hair most people lose daily will not
contain a root or nDNA, but it does have mitochondrial DNA (mDNA). MDNA, which cannot
be used for individualization, can narrow the source of the hair down to a certain family group
(mDNA is passed from mother to all offspring). http://www.crimemuseum.org/blog/what-canyou-tell-from-forensic-hair-examination
7. Cashmere is from what animal?
Goat
8. What are the different types of fiber?
9. What are examples of synthetic fiber?
Polyester, latex, nylon, rayon
10.What is the composition of paint?
11.What are the types of coating on an automobile?
Clear coat-applied to protect the color of the car
Basecoat-color of the car
Primer-easier to apply the base coat and levels the surface to apply the
paint
12.Describe what happened during the Williams case.
Before Wayne Williams became a suspect, the Georgia State Crime Laboratory located a number of
yellowish-green nylon fibers and some violet acetate fibers on the bodies of victims murdered in the
Atlanta area. The fibers appeared to have a common source. Shortly after Williams became a suspect,
the investigators determined the source of the fibers' manufacture. The next step was to determine
how much of that carpeting has been sold in the Atlanta area. Further investigation traced the fiber to a
limited amount of carpeting manufactured by West Point Pepperell. To convey the unusual nature of
the Williams carpet, investigators developed a numerical probability from that company's data. They
determined that the chance of randomly finding a housing unit with this type of carpet was 1 in 7,792.
To any experienced forensic fiber examiner, the fiber evidence linking Williams to the murder victims
was overwhelming. The prosecution undertook to educate the jury about fiber evidence, using over 40
charts and over 350 photographs. In discussing the significance of an association based on textile
fibers, it emphasized that the more uncommon the fibers, the stronger the association. The association
becomes even stronger when multiple fiber matches become the basis of the association, which was
true in the Williams case. Transferred fibers do not stay with a person long, so that the fibers on a
murder victim are most likely from the scene of the crime. Expert witnesses testified that it was highly
unlikely that any environment other than that present in Wayne Williams' house and car could have
produced the combination of fibers and hairs found on the victims, especially when there were so
many varied origins. Additional evidence linked 10 other victims to 28 different fiber types, only 1 of
which was common
13. What is the difference between tempered and non tempered glass?
14. How can you tell if hair was forcibly removed or just fallen out?
Hair naturally fallen out will still have bulb in tact, neat and organized
Hair forcebally removed may have tissue still attached, could lead to tearing
like below: