The Forensic Analysis of Hair By Mrs. Romero

Root of Hair 3 Stages of Growth (different looking roots) Anagen –initial growth phase may last up to 6 years, which hair follicle is actively producing hair, root is flame shaped. When pulled this root may contain a follicular tag (rich source of DNA) Catagen –transition phase (2-3 weeks), root is elongated appearance as root bulb shrinks and is being pushed out of hair follicle. Telogen –Hair growth has ended—during two-six months period, the hair will be pushed out of the follicle causing the hair to shed naturally.

Parts of a hair strand Tip/ End of Hair Often seen burned cut, razored, or with split ends

Parts of the Hair Shaft Cuticle – The scale structure covering the exterior of the hair Cortex – The main body of the hair shaft Medulla – A cellular column running through the center of the hair. Medullary Index – Measures the diameter of the medulla relative to the diameter of the hair shaft. Humans < 1/3 Animals > 1/2

Morphology: Cuticle Protective coating made of overlapping scales, produce a characteristic pattern Scales always point toward tip of hair Not useful in individualizing human hair Can be used for species identification

Morphology: Cortex The cortex varies in: Thickness Texture Color The color, shape and distribution of the granules provide points for forensic comparison

Cortex 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.

Morphology: Medulla Canal like structure of cells that runs through the center of the cortex ABSENT

Medulla The medulla may vary in: Thickness Continuity - one continuous structure or broken into pieces Opacity - how much light is able to pass through it It may also be absent in some species.

How does scalp hair vary by race? Asian/Native American Round hair shaft - straight Large pigment granules Patchy distribution of pigment Usually continuous medulla European/Caucasian Slightly round to oval hair shaft (straight to curly) Finer pigment granules More even distribution of pigment Usually absent or fragmented medulla

How does scalp hair vary by race? African American Flat to oval hair shaft (curly to kinky) Largest and most dense pigment granules that are unevenly distributed Absent or fragmented medulla

HEAD HAIR: Caucasian (left) Asian/Native American ( bottom left) African American (bottom right)

Can The Body Area From Which A Hair Originated Be Determined? SCALP HAIR: small variation in diameter uniform distribution of pigment color PUBIC HAIR short and curly wide variation in diameter. BEARD HAIR coarse, triangular in cross section blunt tips from cutting or shaving.

Can the Age & Sex of an Individual Be Determined from a Hair Sample? AGE - cannot be determined from a hair examination with certainty (except an infant). SEX - can be determined if DNA is found on the hair.

Is It Possible to Determine If Hair Was Forcibly Removed from the Body? Hair naturally falling off the body will show a root without any follicular tissue. A hair root with follicular tissue means that the hair had been pulled out either by another person or by brushing.

This is the best source of DNA in hair. How Can We Individualize Human Hair? DNA from the follicular tag can be matched to one individual FOLLICULAR TAG – a translucent piece of tissue surrounding the hair’s shaft near the root. This is the best source of DNA in hair.

Forensic Analysis of the Hairs Humans hairs can be separated from animal hairs in any number of ways, including the medullary ratio, characteristics of the medulla, and the scale patterns of the cuticle. Different species of animals can be identified quite easily using the same basic principles.

Comparison Microscope

Identification and Comparison Compare: Length Color Diameter Presence or absence of medulla Distribution, shape and color intensity of the pigment granules present in the cortex Dyed, bleached or natural hair

Collection of Hair Evidence Once collected, the hair evidence should be packaged into paper packets. If sticky tape or a lint roller are used, the entire surface used should be packed into a polyethylene storage bag – easy to see through, but with no direct contact. Control samples need to be collected from the victim, suspect, and other individuals who could have left evidence at the scene. Take from all pertinent regions of the body; 50 head hairs, 24 pubic hairs. Root still in tact is preferable.

Collection of Hair Evidence The search for and collection of hair evidence should begin as soon as possible. Hair evidence is easily transferred to and from the crime scene. A special filtered vacuum cleaner may be used to collect hairs and fibers in mass from carpet, bedding, etc. If the evidence is stuck to another object, the entire object should be packaged and labeled.