1. Hair Evidence Standard
Students will demonstrate the ability to collect, preserve, and identify evidence found at a crime scene.
Objectives
1. Describe the cuticle, cortex, medulla, and root of hair.
2. Explain the distinction between animal and human hairs.
3. List hair features that are useful for the comparison of human hair.
4. Explain the proper collection of hair evidence.

2. The Biology of Hair
An appendage of the skin that grows out of an organ known as the hair follicle.
Extends from its root or bulb embedded in the follicle, continues into a shaft, and terminates at a tip end.
Hair follicle: sac-like anatomical structure from which hair grows. Sebaceous gland: gland that secretes sebum, which lubricates the skin and hair. Root of hair: part of the hair implanted in the dermis. Epidermis: outer layer of the skin. Hair shaft: a filament that grows from the skin.

3. Why do we have hair?
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4. Why do mammals have hair?
1. Warmth 2. Decrease friction 3. Protect against sunlight 4. Act as a sense organ

5. Skin and Hair Structure

6. The Shaft of Hair
Composed of three layers: cuticle, cortex, and medulla.

7. Hair Structure
Compare hair to a pencil.

8. Cuticle of Hair
Outside covering of hair that resists chemical decomposition.
Formed by overlapping scales that point towards the tip end of the hair.
Scales are made from hardened/keratinized cells that come from the follicle.
A hair with a damaged cuticle, perhaps from brushing, coloring, or blow-drying. The hair looks dull, and scales flaking off may expose the inner layers, leading to further damage.
Cuticle of a healthy hair. The scales lie flat, and are covered with oil, making the hair feel smooth and look glossy. The scales make the hair stiff, and protect the inside

9. Cuticle Patterns
The coronal, or crown-like scale pattern, is found in hairs of very fine diameter and resemble a stack of paper cups. Coronal scales are commonly found in the hairs of small rodents and bats but rarely in human hairs.
Spinous or petal-like scales are triangular in shape and protrude from the hair shaft. They are found at the proximal region of mink hairs and on the fur hairs of seals, cats, and some other animals. They are never found in human hairs.
The imbricate or flattened-scale type consists of overlapping scales with narrow margins. They are commonly found in human hairs and many animal hairs

10. Cortex of Hair Found within the cuticle.
Cortex of a damaged hair. A split end, caused when a hair shaft is pulled apart. Many split ends give hair a frizzy appearance, and cause tangles.
Found within the cuticle.
Made of spindle-shaped cortical cells aligned parallel to length of hair.
Within the cortex are pigment granules made by melanocytes that give hair its color.

11. Three Parts of Hair Composed of:
Cuticle— overlapping scales; protects cortex
Cortex— made of keratin (protein which makes hair strong and elastic) and imbedded with pigment; changes with perms, dyes, etc.
Medulla—innermost layer; purpose unknown

12. Your natural Hair color is determined by three factors
1. The type of natural color pigment melanin present in your hair's cortex.
Eumelanin (black pigment)
Phenomelanin (red/yellow pigment)
2. How many melanin granules exist
3. Whether those granules are close together or far apart
The process of pigmentation consists of three phases: activation, synthesis, and expression.
The first step is the activation of the melanocyte by one of several triggers that begins the
enzymatically-mediated synthesis of the melanin, starting with the amino acid tyrosine. In
other words, the activation phase occurs when the melanocytes receive some sort of stimulus
that causes them to go into a defensive mode and begin the melanin production
process. Melanocytes are activated by a variety of stimulants: stress, acne, hormones, and
inflammatory processes such as exposure to UV radiation or other free radical damage. All
these factors trigger the cells in the upper part of the skin to produce a variety of small
chemical “messengers,” called hormones, and more specifically melanocyte stimulating
hormone (MSH). These hormones then travel to where melanocytes are located and activate
the melanocyte production of melanin.
Also smoking, thyroid imbalances, and vitamin B12 deficiencies can turn hair grey.

13. How Melanin pigments determine your natural haircolor:
Black hair contains densely packed melanin granules full of eumelanin.
Brown hair has a loose pattern of eumelanin-filled granules or granules blended with eumelanin and phenomelanin, depending upon its cool or warm tones and its darkness or lightness.
Blonde hair contains few granules with minimal bits of eumelanin. In fact, the eumelanin is so sparse that the color of blonde hair is the color of the hair fiber itself.
Red hair has loosely packed granules containing phenomelanin.

15. What causes gray hair?
As you age, your natural production of pigment slows down and your natural color loses its color strength.
This doesn't happen to every hair at the same time, so the contrast between the hair with no color and the hair that still has some color causes it to look gray.
So how gray your hair actually looks is determined by the percentage of strands with no color vs. the pigmented strands.

16. Medulla of Hair
Collection of cells that look like a canal running through a hair.
Not all hairs have medullae
Can be classified as continuous ( most animals, human rare, Mongoloid race), fragmented (most animals, human) or absent (human).

17. Medulla Shape Humans and most animals cylindrical
Other animals  patterned (ex. Cat medulla looks like string of pearls, Deer medulla looks like round cells occupying the entire hair shaft)

18. Examination of the Medulla

19. Patterns in Animal Species
Examination of Scale Pattern

20. Medullary Index
By looking at the diameter of the medulla divided by the diameter of the hair shaft you can get the hairs’ medullary index.
Medullary Index Values
 Humans <1/3
 Most other animals ≥1/2

21. Comparison of Animal and Human Hair
Humans
Animals
Medulla is fragmented – only some animals and humans
Medulla is cylindrical in shape (most animals)
Medullary Index <1/3
Medulla is absent for most humans
Medulla is continuous for Mongoloid race
Medullary Index ≥1/2
Medulla is present for all animals
Medulla is continuous for most animals
Medulla is patterned for most animals

22. Human Hairs Racial Determination Body Area Age and Sex?
Forcibly Removed?

23. Racial Determination
Usually kinky, containing dense, unevenly distributed pigments.
Cross section is flat to oval in shape.
Mongoloid
Negroid
Usually coarse containing pigment granules larger in size than Caucasians.
Cross sections are round in shape.
Cross section varieties.
Usually straight or wavy with very fine to coarse pigments that are more evenly distributed .
Cross section are oval to round in shape.
Caucasoid

24. Head Hairs Long with moderate shaft diameter and diameter variation
Medulla absent to continuous and relatively narrow when compared to the structure of hairs from other body areas
Often with cut or split tips
Can show artificial treatment, solar bleaching, or mechanical damage
Soft texture, pliable

25. Pubic Hairs Shaft diameter coarse with wide variations and buckling
Medulla relatively broad and usually continuous when present
Root frequently with tag
Tip usually tapered, rounded, or abraded
Stiff texture, wiry

26. Limb Hairs Diameter fine with little variation
Gross appearance of hair is arc-like in shape
Medulla is discontinuous to trace with a granular appearance
Soft texture
Tips usually tapered, often blunt and abraded, rounded scale ends due to wear

27. Facial Hairs (Beard/Mustache)
Diameter very coarse with irregular or triangular cross-sectional shape
Medulla very broad and continuous, may be doubled

28. Chest Hairs Shaft diameter moderate and variable
Tip often darker in color, long and fine, arc-like
Medulla may be granular
Stiff texture

29. Axillary or Underarm Hairs
Resemble pubic hairs in general appearance, but less wiry
Medullary appearance similar to limb hairs
Diameter moderate and variable with less buckling than pubic hairs
Tips long and fine, frequently with bleached appearance

30. Other Body Hairs
Eyebrow: Stubby, some diameter fluctuation, saber-like in appearance
Eyelash: Short, stubby with little shaft diameter fluctuation, saber-like in appearance
Trunk: A combination of features of limb and pubic hairs, a transitional hair

31. Tip of the Shaft
Burned Cut Razored Split

32. Root of Hair Provide the tools to produce hair and continue its growth
3 Stages of Growth (different looking roots)
Anagen -initial phase may last up to 6 years, root is flame shaped
Catagen –transition phase (2-3 weeks), root is elongated
Telogen –phase where hair naturally falls out of the skin, root is club-shaped

33. Hair Growth Cycle

34. Forcibly Removed?
Pulled Forcibly Removed Shed

35. Brushed-out hairs all have this kind of root.
A normal telogen hair with a hard 'club' end, seen under (left) a light microscope and (right) an electron microscope
This is an anagen hair, one which was pulled out and not ready to be shed.
An anagen hair that has been plucked out: notice the soft, sticky tail

36. Collection of Hair Evidence

37. Collection of Hair Evidence
Questioned and Reference hair must come from same area of the body; one cannot, for instance compare head hair to pubic hair.
The collection of 50 full length hairs from all areas of the scalp will normally ensure a representative sampling of head hair.

38. Collection of Hair Evidence
A minimum collection of 24 full length hairs should cover the range of characteristics present in this type of hair.
All collected hairs must be full-length so that the investigator can see if the color and morphological features vary throughout the length of the hair.

39. Packaging of Hair Evidence
Recover all hair present.
If possible, use fingers or tweezers to pick up hair, place in paper bindles or coin envelopes which should then be folded and sealed in larger envelopes.
Label the outer sealed envelope.
If hair is attached, such as in dry blood, or caught in metal or a crack of glass, do not attempt to remove it but rather leave hair intact on the object.
If the object is small, mark it, wrap it, and seal it in an envelope.
If the object is large, wrap the area containing the hair in paper to prevent loss of hairs during shipment

40. Hair Scales point to end of hair.
The end of the hair is the oldest end.
Why is this important?