CHAPTER
3
The Study of Hair
Objectives
3.1 Identity the various parts of a hair.
3.2 Describe variations in the structure of the medulla, cortex, and cuticle.
3.3 Distinguish between human and nonhuman hair.
3.4 Determine if two examples of hair are likely to be from the same person.
3.5 Explain how hair can be used in a forensic investigation.
3.6 Calculate the medullary index of a hair.
3.7 Distinguish hairs from individuals belonging to the broad racial categories.
Chapter 3 Reading Guide
Define all key vocabulary terms listed below:
1. Class evidence
2. Comparison microscope
3. Cortex
4. Cuticle
5. Hair follicle
6. Individual evidence
7. Keratin
8. Medulla
9. Melanin granules
10. Neutron activation analysis
11. Trace evidence
Introduction
1. Why (and when) is hair considered class evidence?
2. Explain how the secondary transfer of hair occurs.
3. When is hair considered individual evidence?
History of Hair Analysis
1. When did investigators recognize the importance of hair analysis as trace evidence?
2. Describe The Principles and Practice of Medical Jurisprudence.
3. Describe the Le Poil de l’Homme et des Animaux (The Hair of Man and Animals).
4. Describe Dr. Sydney Smith’s use of the comparison microscope.
5. Describe the advances in hair analysis throughout the 20th century.
The Function of Hair
1. List the four functions of body hair.
2. Explain the difference between hair and fur.
3. Explain in detail how hair regulates body temperature in response to being cold and in response to being warm.
4. Describe human hair in terms of quantity and abundance.
The Structure of Hair
1. Draw Figure 3.2
2. Define follicle.
3. Describe the components of the hair associated with the follicle:
a. Papilla
b. Sebaceous gland
c. Erector muscle
d. Nerve cells
4. Describe the structure of the hair shaft.
5. Describe the components of the hair associated with the shaft (in terms of the pencil analogy):
a. Medulla
b. Cortex
c. Cuticle
The Cuticle
1. Define cuticle.
2. Describe the orientation of hair cuticle scales.
Types of Cortex
1. Define cortex.
2. Describe the components of the hair associated with the cortex:
a. Melanin
Types of Medulla
1. Recreate Figure 3.6 Five Different Patterns of Medulla are identified in forensic hair analysis.
Types of Hair
1. Explain how hair can vary in terms of shape, length, diameter, and texture.
Hair from Different Parts of the Body
1. List the six types of human hair on the body.
2. Describe the cross-sectional shape of hair in the various regions of the body.
3. Describe the typical characteristics of arm and leg hair.
4. Describe the typical characteristics of beard hair.
The Life Cycle Of Hair
1. List the stages of hair development in order.
2. Describe the anagen stage.
3. Describe the catagen stage.
4. Describe the telogen stage.
Treated Hair
1. How does bleaching impact hair structure?
2. How does dyeing hair impact hair structure?
3. What is the approximate rate of hair growth per month? Per day?
4. How can you determine the last time hair was color-treated? Then answer the following sample problem:
a. If the unbleached root region measured 3.7 cm how many months/weeks has it been
since the individual has color treated their hair?
Racial Differences
1. Recreate Figure 3.10.
Animal Hair and Human Hair
2. How does the pattern of pigmentation differ in animals and humans?
3. How does the medulla index differ in animals and humans?
4. Practice calculating the medullary index for the following examples and identify whether it is an
animal or human based on the medullary index:
a. Diameter of medulla = .60 mm, Diameter of entire hair = .80mm
b. Diameter of medulla = .20mm, Diameter of entire hair = .80mm
c. Diameter of medulla = .15mm, Diameter of entire hair = .80mm
5. How does the cuticle pattern differ in animals and humans?
Using Hair In An Investigation
1. Describe Locard’s exchange Principle.
2. Describe the methods by which hair can be collected at a crime scene.
3. How do investigators conduct hair analysis?
Microscopy
1. What are the macroscopic characteristics of hair?
2. What are the microscopic characteristics of hair?
3. Describe how phase contrast microscopy works.
4. Describe how fluorescence microscopes work.
5. Describe how electron microscopes work.
Testing For Substances In The Hair Shaft
1. How does hair absorb chemicals from the skin?
2. How is hair tested for chemicals (i.e. describe chemical analyses of hair)?
3. How can you establish a timeline for exposure to poisons or other toxins?
4. Describe in detail Neutron Activation Analysis (NAA).
Testing The Hair Follicle
1. What is a follicle tag?
2. How can follicle tags be utilized in forensic analyses?
Case Studies
Summarize and study the following case studies:
 Neutron Activation Analysis of Hair, Gaetane Bouchard (p. 48)
 Alma Tirtsche (1921) (p. 59)
 Eva Shoen (1990) (p. 60)
 Napolean’s Hair (p. 60)