Chp. 10 Hair Analysis

PLEASE DO NOW How many hairs does the average person have on his/her head? All Brown hair Red hair Blond hair What information can a forensic scientist determine from a human hair?

Hair as Evidence Continually falls from the body About 100 hairs fall out each day Not readily lost or displaced Goes unnoticed by criminal Not easily destroyed Useful associative evidence since it originates directly from the individual

Hair Structure Hair = epidermal appendage that grows out of the skin from an organ known as the follicle Root = portion of hair that lies in follicle Bulb = enlarged base of root Dermal papilla = connective tissue surrounded by bulb Shaft = portion of hair above skin’s surface Composed primarily of keratin Feature unique to mammals

Hair Growth Average period of hair growth 1,000 days Grows 1 cm per month 3 distinct growth phases Anagen (80-90% of hairs) Follicle actively producing hair Catagen (2% of hairs) Transitional period Telogen (10-18% of hairs) Follicle dormant/resting

Hair Growth Anagen Phase Cells in dermal papilla undergo mitosis and grow up to form hair shaft Bulb is described as flame shaped

Hair Growth Catagen Phase Cells in the shaft continue to differentiate but no more pigmentation or color produced in hair towards root Bulb of the root shrinks and becomes surrounded by the club – a capsule of cells

Hair Growth Telogen Phase Hair anchored in follicle only by club Germ cells below club getting ready to form next hair Dermal papilla looks like a ball below germ cells waiting to be surrounded by next bulb

Hair Structure The shaft of the hair has 3 layers Cuticle = thin translucent scale layer surrounding shaft Cortex = main body of hair shaft Medulla = central canal-like structure

Cuticle Made up of overlapping, nonnucleated, pigment-free, keratinized cells that have formed scales As many as 6 layers of scales per hair Scales always point away from the root Outer and inner cuticle margins can be: Cracked Ragged Serrated Flattened

Cuticle

Cuticle Viewing cuticle scales Mount hair between glass slides Prepare a clear cast of the cuticular surface Scanning electron microscope

Cortex Composed of elongated keratinized filaments aligned together parallel to the length of the hair Contained within cells of cortex Cortical fusi = delicate air spaces Vary in amount, size, shape and distribution Appear dark with transmitted light and bright with direct light Hair pigment = solid structure that gives hair color Vary in size, shape, distribution and density Appear dark and granular Smaller than cortical fusi Ovoid bodies Solid structures that are oval in shape Larger than pigment granules

Cortex

Cortex

Medulla Cellular column running through the center of the cortex Function is to increase protective properties of hair by adding internal space Medulla structure on humans is amorphous Pattern can be absent, fragmental, interrupted, or continuous Appearance will vary from person to person and within hairs of the same individual

Medulla

Hair as Evidence Class evidence Have to compare evidence against reference samples To collect samples: Bright light aids in the visualization of questioned hairs at a crime scene Stored in paper packets or between sealed glass slides Wide transparent tape obtains difficult to see hairs from clothing and carpets Note location from where collected To collect reference samples: Collected from both victim and suspect About 50 samples collected for comparison Should be combed and pulled to represent all growth stages Should be taken from each region of the area Must represent any chemically treated areas of the hair

Identification of Human Hair First step in the forensic investigation of human hair is to identify the hair in question in the following categories: Species Origin Racial Origin Somatic Origin A direct comparison with a reference hair can only be made after the hair is classified in this way

Species Origin 3 Types of Animal Hairs Vibrissa Tactile and sensitive whiskers Largest and longest hairs on body usually Bristle/Guard Coarse hairs that make up the protective outer coat Distinctive in appearance and morphology between different animal families Wool/Fur Fine short hairs that cover the body and make up the inner coat Provides insulation from wet and cold

Species Origin 4 Types of Human Hairs Primordial Coarse and whisker like Appear during 3rd month of gestation Grow on upper lips, eyebrows, palms and soles of fetus Lanugo Fine, soft, unmedullated and unpigmented Replace primordial hairs but shed after 6 months of gestation Vellus Fine, soft, unmedullated and short (2 cm) Spread uniformly over body surface except for palms, soles, lips, and nipples Terminal Replace vellus hairs at specific sites and stages of life Scalp and eyebrows, pubic areas, face, chest, back, arms and legs

Species Origin Cuticle Human Imbricate scales = scales are small, flattened and with little serration Animal Exhibit a wide range of cuticular patterns

Species Origin - Cuticle Human Hair – Imbricate Scales Mink Hair – Spinous Scales Bat Hair – Coronal Scales

Species Origin Cortex Human Untreated human hair is uniform in color Pigmentation granules are evenly distributed or slightly more dense toward cuticle Animal Hairs exhibit rapid color changes along the shaft called banding Pigmentation granules are more dense toward the medulla

Species Origin - Cortex Pigment Distribution in Human Hair Pigment Distribution in Animal Hair

Species Origin Medulla Human Rarely 1/3 width of hair shaft Structure is amorphous Pattern can be absent, fragmented, interrupted, or continuous Animal More than 1/2 width of hair shaft Distinct medulla structure between species

Species Origin - Medulla Uniserial and Multiserial Ladder Medulla in Rabbit Hairs Vacuolated Medulla in Dog Hair Lattice Medulla in Deer Hair

Racial Origin Caucasian 70-100 μm Oval Even Medium Uncommon Asian Diameter Cross Section Pigmentation Cuticle Undulation Caucasian 70-100 μm Oval Even Medium Uncommon Asian 90-120 μm Round Dense Thick Never African American 60-90 μm Flat Dense and Clumped - Prevalent

Caucasian Hair

Mongoloid (Asian) Hair

Negroid (African American) Hair

Somatic Origin Scalp: Head hair, 100-1000mm long, 25-125 um diameter; 0.4 mm/day growth; small root; tapered tip; little diameter variation; various medullation; often with cut tips may be artificially treated Pubic: Pudendal; 10-60 mm long; coarse diameter and prominent diameter variation and buckling; broad medulla; follicular tags common; asymmetrical cross section twisted and may be straight, curved, or spirally tufted Vulvar: Secondary pubic hair; finer and shorter; may be abraded Chest: Pectoral; moderate to considerable diameter variation; long fine archlike tip; usually longer than pubic hair Beard: Facial hair; very coarse; 50-300 mm long; large root, irregular structure; often triangular cross section; complex medullation; blunted or razor cut tip; grows 0.4 mm/day Axillary: Arm pit; 10-50 mm long; grows 0.3 mm/day; coarse; blunt tip, abraded or frayed; usually straighter than pubic hair; many cortical fusi; sometimes yellowed and bleached Eyebrow: 1 cm long; 0.16 mm/day growth; curved; relatively coarse for length; smooth curve with punctuate tip and large medulla Eyelash: Ciliary; less than 1 cm long; short curved pointed hair Limb: Leg and arm hair; 3-6 mm long; fine tip; irregularly medullated; often indistinctly and slightly pigmented Ear: Tragi; pinnae; downy Buttocks: Anal hair; short blunted and abraded hair Nose: Similar to facial hair (beard)

Pubic Hair Limb Hair Beard Hair

Association of Human Hair Characteristics used for hair comparison Structure Color Cuticular Traits Length Acquired Characteristics

Structure of Hair

Color of Hair

Cuticular Traits

Acquired Characteristics

Scissor Cut Razor Cut Split End Broken/Clippers

Microscopy 3 types of microscope used: Mounting choices Stereoscopic Microscope - gross observations of the hairs Study trace evidence on the hair’s surface, spatial configuration, roots, and tips Compound or Polarizing Microscope - allows for higher magnification and resolution Delineates hair’s finer structural characteristics (pigment, scale, structure, cortical fusi, medulla) Transmitted Light Comparison Microscope - compare known and unknown hairs side-by-side Mounting choices Dry mount Temporary liquid mounting media Permanent mounting media

Conclusions from Comparisons One of 3 conclusions can be reached: The hairs matched in microscopic characteristics indicating an association The hairs were not alike and therefore did not originate from the same individual No conclusion can be drawn from the evidence Factors affecting degree of certainty associated with conclusion: Number of unknown hairs found to be similar to reference hairs Number of microscopic features observed The presence of unusual characteristics Condition of specimens Completeness of reference sample collection

Was Hair Forcefully Removed? Look for follicular tag Tissue from the follicle attached to the root of the hair If a hair pulled from the body was securely attached to the follicle (anagen stage) a follicular tag will be present If there: Yes hair was pulled out If absent: Could have fallen out naturally Could have been pulled out but cannot tell because If the hair was in the telogen phase, no tissue would be attached Some individuals lack follicular tissue on plucked anagen hairs

A hair forcibly removed from the scalp will exhibit stretching and damage to the root area (PULLED) Forcibly removed hairs may have tissue attached called the follicular tag Naturally shed hairs dislodged through combing display undamaged, club-shaped roots

Is Hair from a Dead Body? Look for postmortem banding If present: A dark band around the hair near the root where the skin surface meets the hair shaft Found on hairs pulled from decomposing skin If present: May indicate that the body was moved after death

Individualization of Human Hair DNA allows for the individualization of hair Nuclear DNA Found in the follicular tag Will identify hair with one individual Mitochondrial DNA Found throughout cells of hair Will identify hair to individuals of the same maternal line

Quick Review 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: If the source is human or animal 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

Review of Hair Analysis Comparison Identification DNA Collect Reference Samples

Questions?