1. Honors Forensic Science
Chapter 6
Mr. E. Davis
Honors Forensic Science

2. Hair & Fiber Vocabulary Words
Class Evidence - material that connects an individual or thing to a certain group.
Comparison Microscope - a compound microscope that allows the side-by-side comparison of samples, such as of hair or fibers.
Cortex - the region of a hair located outside of the medulla containing granules of pigment.
Cuticle - the tough outer covering of a hair composed of overlapping scales.
Hair Follicle - the actively growing root or base of a hair containing DNA and living cells.
Individual Evidence - a kind of evidence that identifies a particular person or thing.
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Keratin - a type of fibrous protein that makes up the majority of the cortex of a hair.
Medulla - the central core of a hair fiber.
Melanin Granules - bits of pigment found in the cortex of a hair.
Neutron Activation Analysis - a method of analysis that determines composition of elements in a sample.
Trace Evidence - small but measurable amounts of physical or biological material found at a crime scene.
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Chemical Property - property of a substance that describes how it reacts in the presence of other substances.
Chromatography - any of several processes used to separate a mixture into its individual components based on their attraction to a stationary liquid or solid.
Confirmatory Test - test done to establish with certainty the characteristics of a substance.
Frequency - the number of waves that pass a specific point within a given time; usually expressed in cycles per second or hertz (Hz).
Physical Property - property of a substance that can be observed or measured without changing the chemical identity of the substance.
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Presumptive Test - a test to screen evidence and narrow down the possible type of a substance.
Rf value - retention factor; in paper and thin-layer chromatography, ratio of the distance a substance traveled to the distance the solvent traveled.
Wavelength - the distance between crests, or peaks, of two consecutive waves.
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7. Forensics Hair Analysis
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The scientific study of hair was introduced when one of the first scientific reports was published in in France. 
In the early 20th century, the study of hair expanded.  Professor John Glaister's published "Hairs of Mammalia from the Medico-legal Aspect" in 1931 which was a source for information on hair analysis. 
Then "Microscopy of Hairs: A Practical Guide and Manual" was published by John Hick which showed groundwork for hair evidence analysis.
History of Hair/Fiber
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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.
Hair color is mostly the result of pigments, which are chemical compounds that reflect certain wavelengths of visible light.
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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.).
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 nuclear DNA, the root must be present. The hair may also be tested using mitochondrial DNA whether the root is present.
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CSI – Hair Fibers
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Hair Structure
Hair is composed of three principal parts
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Hair Morphology
Hair is an appendage of the skin that grows out of an organ known as the hair follicle
Grows from hair follicle
Root is embedded in follicle
Shaft has 3 parts
Cuticle
Cortex
Medulla
Terminates at a tip end
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Hair Fibers
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Anatomy of a Hair
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Hair Follicle
Hair is an appendage of the skin that grows out of a hair follicle.
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Hair Follicle
The follicle contains more than enough cells for simple DNA Analysis.
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21. Root
The root and other surrounding cells in the hair follicle provide the tools necessary to produce hair and continue its growth.
When pulled from the head, some translucent tissue surrounding the hair’s shaft near the root may be found. This is called a follicular tag.
By using DNA analysis on the follicular tag, the hair may be individualized.
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23. Hair as Evidence Hair is composed primarily of the protein keratin
Defined as slender outgrowths of the skin of mammals
Each species of animal possesses hair with characteristic length, color, shape, root appearance, and internal microscopic features that distinguish one animal from another
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Hair as Evidence
Variability exists in types of hairs found on body of an animal
Humans
Head, pubic region, arms, legs & other body areas have characteristics that can determine their origin
Hair types include coarse outer hairs or guard hairs (finer fur hairs, tactile hairs [whiskers], & others that originate from tail & mane)
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Hair Fibers
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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
Hair Cuticle
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Hair Cuticle
Is the outside covering of hair
Gives hair resistance to chemical composition & stability (retaining features over a long period of time
Formed by overlapping scales that always point toward the tip end
Scale pattern is useful in species identification but not a useful characteristic for individualizing human hair
Variety of patterns formed by animal hair makes it an important feature for species identification
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Hair Cuticle
Characteristics of the cuticle may be important in distinguishing between hairs of different species but are often not useful in distinguishing between different people.
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The cortex varies in:
Thickness
Texture
Color
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.
Cortex
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30. Cortex Main body of hair shaft The interior of the hair
Color, shape, distribution of the granules provide important points of comparison
It is embedded with pigment granules that give hair its color
The interior of the hair
Main body of hair shaft
Cortex
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Thickness
Continuity - one continuous structure or broken into pieces
Opacity - how much light is able to pass through it
The medulla may vary in:
It may also be absent in some species.
Medulla
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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.
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33. Group of cells having appearance of a central canal running through a hair
Sometimes it is the predominant feature, occupying more than ½ the diameter (varies by species)
Medullary index is the diameter of medulla relative to diameter of hair shaft
Humans is less than 1/3
Other animals, value is ½ or greater
Medulla
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Medulla
Presence & appearance vary between individuals & among the hairs in a given individual
Medulla patterns
Continuous
Interrupted
Fragmented
Absent all together
Human head hairs the medulla is usually absent or fragmented; rarely have continuous
Animal medulla is either continuous or interrupted
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Shape of medulla
Cylindrical: humans & many animals
Patterned shape: other animals
Ex. Medulla of cat resembles a string of pearls
Ex. Deer medulla is spherical cells occupying the entire hair shaft
CAT
DEER
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HUMAN
DOG
RABBIT
Medulla Shapes
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CAT

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Shapes of Medulla
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38. FBI Forensic Case – Hair Fibers
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39. Forensics Files – Charred Hair Fibers
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40. FBI – Flawed Hair Analysis
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