TYPES OF HAIRS Primordial hairs - appear as early as the beginning of the third month of gestation; grows on the upper lip, eyebrows, palms and soles of the fetus. Lanugo hairs - found in fetal life, are shed after the sixth month of gestation, and are often found on aborted fetuses. Vellus hairs - are spread uniformly over the body’s surface, except the soles of the feet. Terminal hairs - replace the vellus hairs at specific sites and points of life; are found mainly on the scalp, on the face, chest, back, arms, and legs, and are sex- limited.

HAIR STRUCTURE Hair is an appendage of the skin that grows out of the hair follicle. Hair is composed of a group of keratins that interacts and interconnect to from stable fibrils, and is comprised of: Cuticle Cortex Medulla

HAIR STRUCTURE Diagram of Hair in Skin

HAIR STRUCTURE Cuticle - a thin translucent layer surrounding the hair shaft. consists of overlapping, non-nucleated, pigment-free cells which form scales. the scales point away from the root towards the tip of the hair shaft.

HAIR STRUCTURE Cuticle Structure Coronal

HAIR STRUCTURE Cuticle Structure Spinous

HAIR STRUCTURE Cuticle Structure Imbricate

HAIR STRUCTURE Medulla - a cellular column running through the center of the cortex. Its presence varies from person to person and between hair of a given individual. The medulla originates from matrix cells closest to the dermal papilla, and large amounts of glycogen are found in medullary cells.

HAIR STRUCTURE Medulla (continued). Main function is to increase the protective properties of the hair by adding internal air spaces to the hair. It occupies about one-third of the hair’s width. Can be classified as absent, fragmented, discontinuous, or continuous.

Medulla Structure

HAIR STRUCTURE Cortex The cortex is the main body of the hair composed of elongated and fusiform (spindle-shaped) cells. It may contain cortical fusi, pigment granules, and/or large oval-to-round-shaped structures called ovoid bodies.

HAIR STRUCTURE Cortex Cortical fusi are irregular- shaped airspaces of varying sizes. They are commonly found near the root of a mature human hair, although they may be present throughout the length of the hair

HAIR STRUCTURE Cortex Pigment granules are small, dark, and solid structures that are granular in appearance and considerably smaller than cortical fusi. They vary in color, size, and distribution in a single hair.

HAIR STRUCTURE Cortex In humans, pigment granules are commonly distributed toward the cuticle as shown in except in red-haired individuals.

HAIR STRUCTURE Cortex Animal hairs have the pigment granules commonly distributed toward the medulla.

HAIR STRUCTURE Cortex Ovoid bodies are large (larger than pigment granules), solid structures that are spherical to oval in shape, with very regular margins. They are abundant in some cattle and dog hairs as well as in other animal hairs.

HAIR STRUCTURE Cortex Ovoid bodies are also found in human hairs.

GROWTH AND REPLACEMENT OF HAIR Mammalian hair follicles go through three (3) distinct growth cycles. Anagen Catagen Telogen

GROWTH AND REPLACEMENT OF HAIR Anagen: The active growth phase; human head hairs spend about two to four months in this phase; 80% to 90% of the hairs are in this growth cycle.

GROWTH AND REPLACEMENT OF HAIR Catagen: The breakdown phase; lasts two to four weeks, 2% of the hairs are in this phase.

GROWTH AND REPLACEMENT OF HAIR Telogen: The resting phase; lasts two to four months, until they fall out naturally or are forcibly removed, about 10% to 18% of the hairs are in this phase.

IDENTIFICATION OF HUMAN HAIR The first step of forensic identification and comparison of hairs begins with whole mount light microscopy. The hair(s) in question must be identified as to species, race and body (somatic) origin. Human hairs can be readily distinguished from animal hairs in several ways, mainly by examining the cuticles and medullae.

IDENTIFICATION OF HUMAN HAIR Racial Origin: Caucasian - Indo European Shaft diameter: moderate with minimal variation (mean diameter for human head hairs - 80um) Pigment granules: sparse to moderately dense with fairly even distribution Cross-sectional shape: oval

IDENTIFICATION OF HUMAN HAIR Racial Origin: Negroid – African Shaft diameter: moderate to fine with considerable variation Pigment granules: densely distributed (hair shaft may be opaque) and arranged in prominent clumps Shaft: prominent twist and curl Cross-sectional shape: flattened

IDENTIFICATION OF HUMAN HAIR Racial Origin Mongoloid - Eastern Asian, Eskimo-Aleutian, and Native American Shaft diameter: coarse and usually with little or no variation Pigment granules: densely distributed and often arranged in large patchy areas or streaks Medulla: prominent (often broad and continuous) Cuticle: thick Cross-sectional shape: round

IDENTIFICATION OF HUMAN HAIR Somatic Origin: Head 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

IDENTIFICATION OF HUMAN HAIR Somatic Origin: Pubic Shaft diameter coarse with wide variations and buckling Medulla relatively broad and usually continuous when present Root frequently with tag Tip usually tapered, rounded, or abraded Stiff texture, wiry

IDENTIFICATION OF HUMAN HAIR Somatic Origin: Limb hairs (arm or leg) Diameter fine with little variation Gross appearance of hair is arc-like in shape Medulla is discontinuous to trace with a granular appearance Tips usually tapered often blunt and abraded, rounded scale ends due to wear Soft texture

IDENTIFICATION OF HUMAN HAIR Somatic Origin Beard or Mustache hairs Diameter very coarse with irregular or triangular cross- sectional shape Medulla very broad and continuous, may be doubled

IDENTIFICATION OF HUMAN HAIR Somatic Origin Chest hairs Shaft diameter moderate and variable Tip often darker in color, long and fine, arc-like Medulla may be granular Stiff texture

IDENTIFICATION OF HUMAN HAIR Somatic Origin 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

IDENTIFICATION OF HUMAN HAIR Somatic Origin: Other Eyebrow: Stubby, some diameter fluctuation, saber-like in appearance Eyelash: Short, stubby with little shaft diameter fluctuation, saber-like in appearance Trunk: A combination of features of limb and pubic hairs, a transitional hair

IDENTIFICATION OF HUMAN HAIR As a rule, most forensic comparisons are conducted using scalp or pubic hairs. Body and limb hairs are generally considered unsuitable for comparison purposes. Artificial Treatment: Bleached Dyed

EXAMPLES OF RACIAL HAIR Caucasian:

EXAMPLES OF RACIAL HAIR Negroid

EXAMPLES OF RACIAL HAIR Mongoloid

VARIATIONS IN COLOR

COLLECTION AND EXAMINATION OF HAIR Always photograph the item and note its location first before collecting it. Always be sensitive to cross-contamination issues. Always wear gloves to collect evidence. Always use clean, unused paper bindles or containers. Use fingers or tweezers to collect crime scene evidence. Collect good representative exemplary (known) hairs from the scalp and/or pubic region. Collect exemplars from both the victim and suspect. Always maintain the chain of custody.

CONCLUSION AND REPORT WRITING Forensic laboratory reports of hair comparisons normally will provide one of three answers: The hairs matched in microscopic characteristics, indicating an association. The hairs are not alike and therefore did not come from the same person. No conclusion can be drawn from the evidence. This may be due to insufficient specimen, racial mixtures, or unsuitable exemplars.

CONCLUSION Types of hairs Hair structure and growth Race and body origin Evidence collection procedures Microscopy and results

REFERENCES Saferstein, R., Forensic Science Handbook, 1992 Prentice - Hall, Inc., Englewood Cliffs, N.J., pp Deadman, H.A., Human Hair Comparison Based on Microscopic Characteristics, Proceedings of the International Symposium on Forensic Hair Comparisons, (Washington, D.C.: Government Printing Office, 1985), pp Linch, Charles A., et. Al, Evaluation of the Human Hair Root for DNA Typing subsequent to Microscopic Comparison, JFS 1998; 43 (2), pp Bisbing, R.E., The Forensic Identification and Association of Human Hair, Forensic Science Handbook, Saferstein, R. ed. Englewood Clifffs, N.J., Prentice-Hall, Inc., 1982, pp Gaudette, B.D., An Attempt at Determining Probabilities in Human Scalp Hair Comparison, JFS., 1973, pp FBI, Microscopy of Hairs, A Practical Guide and Manual, Issue #2, 1977, Washington, D.C., pp