1. Kendall/Hunt Publishing Company
Introduction
Human hair is one of the most frequently found pieces of evidence at the scene of a violent crime. It can provide a link between the criminal and the crime.
From hair one can determine:
human or nonhuman?
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 have been ingested
Kendall/Hunt Publishing Company 1

2. Kendall/Hunt Publishing Company
And there’s more
It can indicate entrance or exit route of the suspect
It can show contact with victim (physical or hit and run)
Kendall/Hunt Publishing Company 2

3. Kendall/Hunt Publishing Company
Skin Structure
Kendall/Hunt Publishing Company 3

4. Kendall/Hunt Publishing Company
Hair Shaft
Composed of:
Cuticle—outside covering, made of overlapping scales
Cortex—inner layer made of keratin and imbedded with pigment; also contains air sacs called cortical fusi
Medulla—inside layer running down the center of the cortex
Kendall/Hunt Publishing Company 4

5. Kendall/Hunt Publishing Company5

6. Kendall/Hunt Publishing Company
The Cuticle
The cuticle is the outermost layer of hair which is covered with scales. The scales point toward the tip of the hair. Scales differ between species of animals and are named based on their appearance. The three basic patterns are:
Coronal
Spinous
Imbricate
Kendall/Hunt Publishing Company 6

7. Kendall/Hunt Publishing Company
Human Scales
In order to visualize the
scales:
paint clear fingernail polish on a glass slide
when the polish begins to dry, place a hair on the polish
when almost dry, lift off the hair and observe the scale imprints
What pattern is seen in
this slide?
Kendall/Hunt Publishing Company 7

8. Kendall/Hunt Publishing Company
The Cortex
The cortex gives the hair its shape.
It has two major characteristics:
Melanin—pigment granules that give hair its color
Cortical fusi—air spaces, usually found near the root but may be found throughout the hair shaft
Kendall/Hunt Publishing Company 8

9. Kendall/Hunt Publishing Company
Hair Shape
Can be straight, curly or kinky depending on the cross-section, which may be round, oval or crescent-shaped
Crescent moon
(Kinky)
Round
(Straight)
Oval
(Curly)
Kendall/Hunt Publishing Company 9

10. Kendall/Hunt Publishing Company
The Medulla
The medulla is the hair core that is not always visible. The medulla comes in different types and patterns.
Types:
Intermittent or interrupted
Fragmented
Continuous
Stacked
Absent—not present
Kendall/Hunt Publishing Company 10

11. Kendall/Hunt Publishing Company11

12. Kendall/Hunt Publishing Company12

13. Kendall/Hunt Publishing Company
Human Medulla
Human medulla may be continuous, fragmented or absent.
Kendall/Hunt Publishing Company 13

14. Kendall/Hunt Publishing Company
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
Kendall/Hunt Publishing Company 14

15. Sample Photomicrographs
Continuous
Clear Medulla
Continuous
Opaque Medulla
Wafer Medulla 15
Copyright © Texas Education Agency All rights reserved.
Images and other multimedia content used with permission. 

16. Kendall/Hunt Publishing Company
The Root
Human roots look different based on whether they have been forcibly removed or if they have fallen out.
Fallen out
Forcibly removed
Kendall/Hunt Publishing Company 16

17. Kendall/Hunt Publishing Company17

18. Kendall/Hunt Publishing Company18

19. Human & Animal Hair 3 Main differences Human Hair Animal Hair Pigment
remains constant in its color and pigmentation throughout the length of the shaft
often exhibits rather rapid and radical color changes
Medulla
thin, taking up no more than 1/3 of the hair shaft diameter; amorphous
very wide; its structure is very regular and well-defined (with certain patterns)
Scale Structure
has overlapping imbricate (or flattened) scales with narrow margins
some have coronal (crown-shaped) scales or spinous (petal-shaped) scales 19
Copyright © Texas Education Agency All rights reserved.
Images and other multimedia content used with permission. 

20. Scales Imbricate Scales Human Imbricate Scales Coronal Scales Diagram
Bat Hair 20
Copyright © Texas Education Agency All rights reserved.
Images and other multimedia content used with permission. 

21. Racial Origin Caucasian
moderate shaft diameter with very little variation
light to moderate pigment density with fairly even distribution
oval-shaped cross-section 21
Copyright © Texas Education Agency All rights reserved.
Images and other multimedia content used with permission. 

22. Racial Origin (continued)
Caucasian Head
Hair cross-section
Caucasian
Head hairs 22
Copyright © Texas Education Agency All rights reserved.
Images and other multimedia content used with permission. 

23. Racial Origin (continued)
Mongoloid
coarse shaft diameter
streaky pigments with heavy density
thick cuticle
round cross-section 23
Copyright © Texas Education Agency All rights reserved.
Images and other multimedia content used with permission. 

24. Racial Origin (continued)
Negroid
fine to moderate shaft diameter
considerable variation throughout the hair shaft with prominent twists and curls
heavy pigment density with aggregate pigment clumpings
flat cross-section 24
Copyright © Texas Education Agency All rights reserved.
Images and other multimedia content used with permission. 

25. Variations
Why do we need to examine each hair sample from root to tip?
Five Regions of a single head hair 25
Copyright © Texas Education Agency All rights reserved.
Images and other multimedia content used with permission. 

26. Hair Comparisons (continued)
Information NOT provided by a hair examination
Age
Gender
(Unless nuclear DNA analysis is performed on its follicular tag)
Information provided by a hair examination
Is it human or animal hair?
What is the possible race of the donor?
What area of the body did it come from?
Could it have originated from the donor of the known standards?
Hair can also be used to distinguish between identical twins (who cannot be distinguished based on their DNA).
because of the environmental effects on hair such as
weather exposure, diet, artificial treatment, etc. 26
Copyright © Texas Education Agency All rights reserved.
Images and other multimedia content used with permission. 

27. Kendall/Hunt Publishing Company
Hair Comparison
Color
Length
Diameter
Distribution of pigment granules
Dyed hair has color in cuticle and cortex
Bleaching removes pigment and gives a yellow tint
Scale types
Medullary pattern
Medullary index
Kendall/Hunt Publishing Company 27

28. Kendall/Hunt Publishing Company
DNA from Hair
The root contains nuclear DNA. If the forcibly removed skin may be attached=follicular tag
The hair shaft contains abundant mitochondrial DNA, inherited from the mother. It can be typed by comparing relatives.
Kendall/Hunt Publishing Company 28

29. Kendall/Hunt Publishing Company
Collection of Hair
Questioned hairs must be accompanied by an adequate number of control samples.
Control Sample
25-50 full-length hairs from all areas of scalp
24 full-length pubic hairs
Kendall/Hunt Publishing Company 29

30. Kendall/Hunt Publishing Company
Hair Toxicology
Advantages:
Easy to collect and store
Is externally available
Can provide information on the individual’s history of drug use or of poisoning.
Collections must be taken from different locations on the body to get an accurate timeline.
Kendall/Hunt Publishing Company 30

31. Kendall/Hunt Publishing Company31

32. Kendall/Hunt Publishing Company
Hair Toxicology
Napoleon died in exile in 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 did him in.
Kendall/Hunt Publishing Company 32