1. Hairs Forensic Science
Presentation developed by T. Trimpe

2. Graphic Organizer Hamburger fold your paper.
With the fold to the left side and the opening to the right, put the title on the front: “Anatomy of Hair”

3. Measure 3 inches down from the line and draw another line.
Open the paper out and measure 2 ½ inches down from the top of the long edge and draw a line.
Measure 3 inches down from the line and draw another line.
2 ½ inches
3 inches
3 inches

4. Hair Physical Evidence A good indicator of individual identity
Resistant to chemical decomposition.
Retains structural features over time
Hair is not an absolute indicator of identity but can be a good indicator of identity

5. The Anatomy of Hair
Hair is generally used as a class characteristic not an individual characteristic:
Individual:  can be related to a particular person or thing
Class: can be related to groups of people or things
Using hair samples to ID a particular individual is very difficult unless the hair root is present.

6. Biology of Hair
Hair is composed of the protein keratin, which is also the primary component of finger and toe nails.
Hair is produced from a structure called the hair follicle.
Humans develop hair follicles during fetal development, and no new follicles are produced after birth.
Sources: &

7. Biology of Hair Hair color is mostly the result of pigments.
which are chemical compounds that reflect certain wavelengths of visible light.
Sources: &

8. Morphology of Hair Three main regions: root, shaft, and tip
Root: The part that was growing in the follicle.  This is the widest part of the hair

9. Morphology of Hair
Shaft:  The middle of the length of the hair (from the root to the tip).  This is where the hair tapers
Tip:  The end of the hair farthest away from the root.  The hair is narrowest at the tip

10. Front Page Graphic Organizer
Hair Tip
Hair Shaft
Sebaceous Gland
Hair Follicle
Arrector Pilli Muscle
Hair Root

11. Biology of Hair
Hair shape (round or oval) and texture (curly or straight) is influenced heavily by genes.
The physical appearance of hair can be affected by nutritional status and intentional alteration
heat curling, perms, straightening, etc.
Sources: &

12. In order to test hair evidence for DNA, the root must be present.
Biology of Hair
The body area (head, arm, leg, back, etc.) from which a hair originated can be determined by the sample’s length, shape, size, color, and other physical characteristics.
In order to test hair evidence for DNA, the root must be present.
Sources: &

13. Hair Structure Hair is composed of three principal parts:
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.

14. Hair Structure Cortex Largest part of hair shaft
Graphic Organizer: Inside top left flap
Cortex
Largest part of hair shaft
Contains most of the pigment granules (melanin)
The cortex varies in:
Thickness
Texture
Color
Info: Image:

15. Graphic Organizer: Inside top right side
Hair Structure
Cuticle
Medulla – central core (may be absent)
Cortex

16. Hair Structure
Cortex
Distribution of the cortex is perhaps the most important component in determining from which individual a human hair may have come.
Microscopic examination can also reveal the condition and shape of the root and tip.
Info: Image:

17. Hair Structure Cuticle Transparent outer layer of the hair shaft
Graphic Organizer: Inside middle left side
Cuticle
Transparent outer layer of the hair shaft
Covered in scales that point toward the tip
Made of scales
Human : flat and narrow (imbricate)
Animal : different types

18. Hair Structure Cuticle The cuticle varies in: Its scales,
Graphic Organizer: Inside middle left side
Cuticle
The cuticle varies in:
Its scales,
How many there are per centimeter,
How much they overlap,
Their overall shape, and
How much they protrude from the surface
Its thickness, and
Whether or not it contains pigment.

19. Hair Structure Graphic Organizer: Inside middle right side
Imbricate “Flattened” Scales
Coronal “Crown Shaped” Scales
Spinous “Spiny” Scales

20. Hair Structure
Characteristics of the cuticle may be important in distinguishing between hairs of different species but are often not useful in distinguishing between different people.

21. Cuticle Man vs. Beast
Human: Tend to be unorganized and overlap like roof shingles
from
from

22. Cuticle Photographs Coronal , crown-like scales Eg Bat
Spinous or petal-like scales.
Triangular in shape and protrude from the hair shaft.
Mink, Seals, Cats
Never found in human hairs.

23. Cuticle Photographs Imbricate or flattened-scales.
consists of overlapping scales with narrow margins.
They are commonly found in human hairs and many animal hairs.

24. Hair Structure Medulla—Center of hair (Predominant feature of hair)
Graphic Organizer: Inside bottom left side
Medulla—Center of hair (Predominant feature of hair)
Can be hollow tube or filled with cells:
Can be absent
Fragmented or segmented
Continuous or doubled
Pigmented or non-pigmented

25. Hair Structure The medulla may vary in: Thickness
Graphic Organizer: Inside bottom left side
The medulla may vary in:
Thickness
Continuity - one continuous structure or broken into pieces
Opacity - how much light is able to pass through it

26. Hair Structure Medulla
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.

27. Medullae in Human Hair Interrupted Continuous Few short breaks
Graphic Organizer: Inside bottom right side
Interrupted
Few short breaks
Continuous
No breaks
(duplicated)

28. Medullae in Human Hair cont
Graphic Organizer: Inside bottom right side
Absent
No medullae visible
Fragmented
Few parts of the medullae visible

29. Photomicrograph of Animal Hair with vacuolated medullae.
Medulla Examples
Photomicrograph of Deer Medulla with lattice-shaped medulla.
Photomicrograph of Animal Hair with vacuolated medullae.
The above examples have a well-defined appearance and came from a rabbit.

30. Animal Versus Human Hairs
Hair Identification
Animal Versus Human Hairs
Human hairs are distinguishable from hairs of other mammals.
Animal hairs are classified into the following three basic types (functions).
Guard hairs that form the outer coat of an animal and provide protection.
Fur or wool hairs that form the inner coat of an animal and provide insulation.
Tactile hairs (whiskers) that are found on the head of animals provide sensory functions.

31. Human vs. Animal Hair
Cat Hair

32. Human vs. Animal Hair
Horse Hair

33. Human vs. Animal Hair
Dog Hair

34. Human vs. Animal Hair
Deer Hair

35. Human vs. Animal Hair
Rabbit Hair

36. Human vs. Animal Hair
Human Hair

37. Hair From Different Parts of the Body
Varies from region to region of the same person.
Six types of hair on the human body
Head hair
Eyebrows and eyelashes
Beard and mustache hair
Underarm hair
Auxiliary or body hair
Pubic hair
Each has its own shape and characteristics

38. Life Cycle of Hair The root: provides for growth of old and new hair
Three phases of hair growth:
Anagen (up to 6 yrs): root attached to follicle for continued growth; root bulb is flame-shaped
Catagen (2-3 weeks): slowed growth; root bulb has an elongated appearance
Telogen (2-6 months): hair growth ends (becomes dormant) and is shed; root bulb is club- shaped (10-18% of hair)

39. Other Factors to Effect Hair
Race
Appearance
Pigment Granules
Cross Section
Other
Picture
European
Generally straight or wavy
Small and evenly distributed
Oval or round of moderate diameter with minimal variation
Color may be blond, red, brown, or black
Asian
Straight
Densely distributed
Round with large diameter
Shaft tends to be coarse and straight
Thick cuticle
Continuous medulla
African
Kinky, curly, coiled
Densely distributed, clumped, may differ in size and shape
Flattened with moderate to small diameter and considerable variation

40. Hair Comparison Highly subjective comparative test.
DNA analysis of hair is a much more reliable testing technique
Nuclear DNA Analysis:
DNA found in the nucleus of the cell
Must have follicular tag or root structure present to test
Mitochondrial DNA Analysis:
DNA found in cellular material outside of the nucleus
Can be tested without follicle or root structure
More copies of mitochondrial DNA in cells

41. Collection and Preservation Of Hair Evidence
Must be submitted with an adequate sample of hair from the victim of a crime, those entering a crime scene, or a suspect.
Hair samples must be obtained from the same parts of the body.
Usually involve head or pubic hair.
Hair must be pulled out of the skin or by clipping it at the skin line.
Hair is collected from the victims of suspicious deaths at autopsy.