I Hair Evidence Why Hairs and Fibers 1

I. Hair Evidence Why Hairs and Fibers? 1. Hair doesn’t easily break down, excellent evidence 2. DNA can be present (root or follicle)-individualized evidence 3. Everyone has it (very common) 4. Easily transferred 5. Can be tested for : a. Drugs b. Toxins c. Heavy metals d. Nutritional deficiencies

II. Hair Structure A. 2 Parts-follicle and shaft *hair follicle-organ that produces hair shaft

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

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.

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

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.

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

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 • 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

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

Medulla from different species RABBIT DOG HORSE RAT HUMAN

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

Let’s practice!!

Medullary Index Practice Letter Type Medulla Index Value Human/Animal A Interrupted / = 6 mm 9 mm 0. 67 Animal Which Animal?

Daily CSI: Count the # of F’s that appear in the sentence • “Fin ished files are the result of years of sci en tific study com bined with the expe ri ence of years. ”

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

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

III. Using Medulla to ID Animal Species

Horse 1. Very thick, dark medulla 2. Continuous medulla

Rabbit • Many strands of medulla.

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

Cat • Medulla pattern looks like a tight string of pearls

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

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

Mouse • Can see relatively large gaps • Can see light passing through medulla

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

Animal ID Practice

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.

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

• Pigment granules are absent in grey hairs

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.

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

A. Race? Yes Usually kinky, containing dense, unevenly distributed pigments. Negroid Cross section is flattened oval in shape. Mongoloid on cti e s ross C Usually straight or wavy with very fine to coarse pigments that are more evenly distributed. Cross section are oval to round in shape. Caucasoid es. i t e i var Usually coarse containing pigment granules larger in size than Caucasians. Cross sections are round in shape.

B. Body Area? Yes Head Hairs • 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

Pubic Hairs Medulla relatively broad and usually continuous when present Shaft diameter coarse with wide variations and buckling Root frequently with tag Tip usually tapered, rounded, or abraded Stiff texture, wiry

Limb Hairs Diameter fine with little variation Gross appearance of hair is arc-like in shape Soft texture Tips usually tapered, often blunt and abraded, rounded scale ends due to wear Medulla is discontinuous to trace with a granular appearance

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

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

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

C. Forcibly Removed? Yes Pulled Forcibly Removed Shed

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.

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 clubshaped

Hair Growth Cycle

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

In Review: What can hair tell us? 1. Part of body hair is from. 2. If hair was forcibly removed (using root structure) 3. Possible race determination. 4. If a suspect might be associated with a victim. 5. Individualize hair to specific person if DNA present in root/follicle.

What hair cannot tell us? 1. Age or sex 2. Match to specific person/individualize

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.

Collection of Hair Evidence

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.

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

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.

Fibers (cont. ) 1. 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

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)

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

Sheep sheep camel goat insect flax cotton tree

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