1. Notes:
Hairs & Fibers

2. Hair Evidence
& Structure

3. I. Hair Evidence Why Hairs and Fibers?
Hair doesn’t easily break down, excellent evidence
DNA can be present (root or follicle)-individualized evidence
Everyone has it (very common)
Easily transferred
Can be tested for :
a. Drugs
b. Toxins
c. Heavy metals
d. Nutritional deficiencies

4. II. Hair Structure A. 2 Parts-follicle and shaft
*hair follicle-organ that produces hair
shaft
Each hair follicle is developed as a fetus. Once born, more are not produced.

5. Hair Structure cont.
Follicle: tissue cells for simple DNA tests

6. Biology of Hair
Humans develop hair follicles during fetal development, and no new follicles are produced after birth.
Hair color is mostly the result of pigments, which are chemical compounds that reflect certain wavelengths of visible light.

7. B. Shaft Structure
Composed of three layers: cuticle, cortex, and medulla.
Draw and label this picture

8. Hair Structure Cuticle – outer coating composed of overlapping scales
Cortex – protein-rich structure around the medulla that contains pigment
Medulla – central core (may be absent)
The structure of hair has been compared to that of a pencil with the medulla being the lead, the cortex being the wood and the cuticle being the paint on the outside.

9. Hair Structure C. The Cuticle 1. scales point towards the tip
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

10. 2. 3 Cuticle Types/Patterns
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, rarely in human hairs.
Spinous or petal-like scales are triangular in shape and protrude from the hair shaft. mink hairs and on the fur hairs of seals, cats, and some other animals; NEVER found in human hairs.
Imbricate or flattened-scale type consists of overlapping scales with narrow margins. They are commonly found in human hairs and many animal hairs
Coronal
Spinous

11. The Medulla
& Medullary Index

12. Hair Structure D. The Medulla 1. Always dark
2. 5 Types: continuous, fragmented, interrupted, absent, serial

13. Medulla from different species
RABBIT
DOG
HORSE
RAT
HUMAN

14. 3. Medullary Index Determines whether hair is human or animal
Decimal between 0 and 1 (0 = absent)
Medullary Index = Width of Medulla
Width of Hair
Index Values
 Humans < 0.33
 Most other animals ≥0.42

15. Let’s practice!!

16. Medullary Index Practice
Letter
Type Medulla
Index Value
Human/Animal
Which Animal?
/ =
6 mm
9 mm A
Interrupted
Animal
0.67

17. Daily CSI: Count the # of F’s that appear in the sentence
“Fin­ished files are the result of years of sci­en­tific study com­bined with the expe­ri­ence of years.”

18. Daily CSI #3: Hair Classification Identify type of medulla and if hair is from human or animal? A B C

19. Daily CSI #3: Hair Classification Answers… A B C
fragmented
absent
continuous

20. Using Medulla to
ID Animal Species

21. III. Using Medulla to ID Animal Species

22. Horse
Very thick, dark medulla
Continuous medulla

23. Rabbit
Many strands of medulla.

24. Rat
Looks like a big mess
Typically two to three strands of pearls

25. Cat
Medulla pattern looks like a tight string of pearls

26. Dog Relatively thin medulla for animals Sometimes looks like human
Can have coronal cuticle pattern

27. Deer Medulla looks like reptile skin
Very thick medulla, almost covers entire width of hair

28. Mouse Can see relatively large gaps
Can see light passing through medulla

29. Microscope Terms Review
3.) Low power obj. lens (scanning lens 40x)
4.) Medium power obj. lens (low power 100x)
Eye piece
(ocular lens)
5.) High power obj. lens (400x)
Body tube
Nose piece
Arm
Low power obj. lens
Med. power obj. lens
Stage
High power obj. lens
Stage clips
Coarse adj. knob
1.) Body tube 2.) Nose piece 3.) Low power obj. lens (scanning lens 40x) 4.) Medium power obj. lens (low power 100x) 5.) High power obj. lens (400x) ) Stage clips 7.) Diaphragm 8.) Light source (illuminator) ) Eye piece (ocular lens) ) Arm ) Stage ) Coarse adjustment knob 13.) Fine adjustment knob ) Base
Diaphragm
Fine adj. knob
Light source
(illuminator)
Base

30. Animal ID Practice

31. Other Factors
That ID Hairs

32. Hair Structure IV. Other Factors that ID hairs
A. The cuticle varies in:
1. Its scales,
How many per centimeter
How much they overlap
overall shape
How much they protrude from surface
2. Its thickness
Characteristics of the cuticle may be important in distinguishing between hairs of different species but are often not useful in distinguishing between different people.

33. Hair Structure B. The cortex varies in: 1. Thickness 2. Texture
3. Color

34. Pigment granules are absent in grey hairs

35. Hair Structure C. The medulla varies in: 1. Thickness 2. Continuity
3. Opacity - how much light is able to pass through it
Like the cuticle, the medulla can be important for distinguishing between hairs of different species, but often does not lend much important information to the differentiation between hairs from different people.

36. IV. If Human Hairs, what can we determine?
Race?
Body Area?
Age and Sex?
Forcibly Removed?

37. A. Race? Yes
Usually kinky, containing dense, unevenly distributed pigments.
Cross section is flattened oval in shape.
Mongoloid
Negroid
Cross section varieties.
Usually coarse containing pigment granules larger in size than Caucasians.
Cross sections are round in shape.
Usually straight or wavy with very fine to coarse pigments that are more evenly distributed .
Cross section are oval to round in shape.
Caucasoid

38. Head Hairs B. Body Area? Yes
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

39. 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

40. 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

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

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

43. 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

44. C. Forcibly Removed? Yes
Pulled Forcibly Removed Shed

45. D. Age and Sex? No If gray, then could be older person.
If long, then could be woman.
If short, then could be man.
Bad to generalize.

46. V. 3 Stages of Hair Growth
1. Anagen –initial phase; may last up to 6 years, root is flame shaped
2. Catagen –transition phase (2-3 weeks), root is elongated
3. Telogen –phase where hair naturally falls out of the skin, root is club-shaped

47. Hair Growth Cycle

48. 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

49. In Review: What can hair tell us?
Part of body hair is from.
If hair was forcibly removed (using root structure)
Possible race determination.
If a suspect might be associated with a victim.
Individualize hair to specific person if DNA present in root/follicle.

50. What hair cannot tell us?
Age or sex
Match to specific person/individualize

51. Collecting Hair Evidence
& Fiber Evidence

52. VI. Collection of Hair Evidence
Questioned and Reference hair
from same area of the body
50 full length hairs from all areas of the scalp = representative sampling
24 full length pubic hairs
must be full-length so that investigator can see if color and morphological features vary throughout the length of the hair.

53. Collection of Hair Evidence

54. VII. Packaging of Hair Evidence
1. Recover all hair present.
2. use tweezers to pick up
3. place in paper bindles or coin envelopes
4. Seal smaller container in larger envelopes
5. Label outer envelope.

55. Packaging of Hair Evidence
6. If hair is attached to something, 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.
a. Small: mark it, wrap it, and seal it in an envelope.
b. Large: photograph, wrap the area containing the hair in paper to prevent loss of hairs during shipment

56. VIII. Fiber Evidence
A textile material that has a length many times greater than its diameter.
A fiber can be spun with other fibers to form yarn
can be woven or knitted to form a fabric.

57. Fibers (cont.) Features to analyze: a. Diameter and shape
b. Specific dye color
c. type of fabric construction
2. important when there is a possibility of fiber transfer between a suspect and a victim

58. Fiber Evidence 3. Matching unique fibers can be very helpful
4. matching common fibers such as white cotton or blue denim fibers is less helpful.
5. multiple fiber transfers between suspect and victim dramatically increases likelihood that these two had physical contact.
6. All about probability (statistical analysis)

59. A. Natural Fibers Cotton: most common plant fibers used
come from plants and animals
Ex: cotton, wool, silk
Cotton: most common plant fibers used
Wool: most common animal fibers used

60. Sheep sheep camel goat insect flax cotton tree

61. B. Synthetic Fibers man-made
More than half of all fibers used in the production of textile materials
Ex: Nylon, rayon, acrylic and polyester
Fibers under a microscope
Cross-section of a man-made fiber