1. Hair 1

2. 2 Do Now: 1.How are the layers of hair similar to the layers of a pencil 2.How can hair be used in a forensic investigation *If students are talking during Do Now – pop quiz (click here) Objective: SWBAT identify the various parts of a hair. SWBAT describe the variations in the structure of the medulla, cortex and cuticle.

3. Hair 3 Introduction From hair, one can determine: If the source is human or animal Race (sometimes) Origin of the location on the source’s body Whether the hair was forcibly removed If the hair has been treated with chemicals If drugs (or poisons) have been ingested

4. Hair 4 Form and Structure of Hair ‡Morphology – form and structure of hair ‡Average human body has about 5 million hairs ‡Blondes average 120,000 strands of hair on their head ‡Redheads have about 80,000 ‡Black and brown hair people have about 100,000 ‡Hairs are continuously shed and renewed at a rate of about 100 each 24-hour period from the scalp alone!

5. Hair 5 Hair Shaft Composed of: Cuticle— clear outside covering of hair shaft, made of overlapping scales (pattern is used to determine species) Cortex—inner layer made of keratin and embedded with pigment; also contains air sacs called cortical fusi Medulla—inside layer running down the center of the cortex

6. Hair 6 The Cuticle The cuticle is the outermost layer of hair which is covered with scales. animals and are named based on their appearance. The three basic patterns are: Coronal- mouse Spinous- cat Imbricate- human

7. Hair 7 The Cortex The cortex gives the hair its shape. Melanin—give hair its color Contains keratin – a tough protein makes hair so resistant to chemical and biological degradation.

8. Hair 8 The Medulla ‡Hair Core ‡Most humans have no medulla or one that is fragmented (except Native Americans and Asians, where medulla is usually continuous) Types: Intermittent or interrupted Fragmented Continuous Stacked Absent—not present

9. Hair 9 Human Medulla Human medulla may be continuous, fragmented, or absent.

10. Hair 10 Hair Classification Activity

11. Hair 11 Exit Ticket 1. What are the three parts of the hair? 2. Can the hair cuticle get you to an individual person? Why or why not?

12. Hair 12 Medullary Index Determined by measuring the diameter of the medulla and dividing it by the diameter of the hair. Medullary index for human hair is generally less than 1/3. For animal hair, it is usually greater than 1/2. mouse

13. Hair 13 Hair Shape and Cross Section Can be straight, curly, or kinky, depending on the cross-section, which may be round, oval, or crescent-shaped. Round (Straight) Oval (Curly) Crescent moon (Kinky) Human hair ranges in diameter from 25-125 µm

14. Hair 14 Racial Characteristics of Hair ‡Risky, but generally… ‡Asians & Native Americans – round cross section with no twisting ‡American & European whites, Mexicans, and people of Middle Eastern background – oval cross section, rarely with a twist or undulation. ‡African heritage – flat to crescent-shaped cross section with twist, undulation and dense, clumped pigmentation. Undulation – (in hair morphology) slight waviness Undulated Twisted

15. Hair 15 Hair Growth Terminology Anagen—hair is actively growing; lasts up to 5 years; includes 80- 90% of hair follicles Catagen—hair is not growing; a resting phase Telogen—follicle is getting ready to push the hair out; lasts two to six months; about 8-10% of hair follicles Grows about 0.4 mm per day, or 1 cm per month; approximately one- half inch per month Replaced about every 3-5 years with new hair Coarser hairs grow at slower rate and fall out less frequently

16. Hair 16 The Root Human roots look different based on whether they have been forcibly removed or they are telogen hairs and have fallen out. Animal roots vary, but in general have a spear shape. Fallen outForcibly removed

17. Hair 17 The Tip Tip of mature hair will taper to a point Recently cut hair is squared off at the tip, but within 2-3 weeks the tip becomes rounded Frayed hair tip results from over-processing (bleach, coloring, straighteners, blow dryer) or age

18. Hair 18 Hair Comparison Color Length Diameter Distribution, shape, and color intensity of pigment granules Scale types Presence or absence of medulla Medullary type Medullary pattern Medullary index Dyed hair has color in cuticle and cortex Bleaching removes pigment and gives a yellow tint

19. Hair 19 DNA from Hair The root contains nuclear DNA. If the hair has been forcibly removed, some follicular tissue containing DNA may be attached. The hair shaft contains abundant mitochondrial DNA, inherited only from the mother. It can be typed by comparing relatives if no DNA from the body is available. This process is more difficult and more costly than using nuclear DNA.

20. Hair 20 Collection of Hair Questioned hairs must be accompanied by an adequate number of control samples. From victim From possible suspects From others who may have deposited hair at the scene Control sample 50 full-length hairs from all areas of scalp 24 full-length pubic hairs

21. Hair 21 Hair Toxicology Advantages : Easy to collect and store Is externally available Can provide information on the individual’s history of drug use or evidence of poisoning Collections must be taken from different locations on the body to get an accurate timeline.

22. Hair 22 Hair as Chemical Indicator ‡Metabolite – a specific product of a substance, formed by chemical processes in the body ‡Drugs and their metabolites, vitamins and poisons can be detected with just a few mm of hair. ‡Provides back up to urine and blood testing ‡Drug metabolites only detectable in urine for approx. 3-5 days from last use. ‡Hair grows at approx. 1 cm per month and will record drug use over a longer period of time. ‡Can establish dietary deficiencies and diseases ‡Oils on scalp can deposit onto hair and will leave evidence of environment ‡Smoke from crack cocaine can be deposited this way ‡May provide a false positive

23. Hair 23 Hair Toxicology, continued Napoleon died in exile in 1821. By analyzing his hair, some investigators suggest he was poisoned by the deliberate administration of arsenic; others suggest that it was vapors from the dyes in the wallpaper that killed him.

24. Hair 24 More about Hair For additional information about hair and other trace evidence, check out truTV’s Crime Library at: www.crimelibrary.com/criminal_mind/forensics/trace/1.html