HAIR ANALYSIS DAY II *

What type of Evidence is Hair? Trace Evidence--any small pieces of material, man-made or naturally occurring Most common examples: Hair Fiber *

Why is Hair Analysis Important? Identifying criminal suspects Identifying crime victims Associating a victim or suspect with a location Determining the type of crime committed *

Hair 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 act. From hair one can determine: Human or animal Race Origin Manner in which hair was removed Treated hair Drugs ingested *

DNA The hair shaft contains abundant mitochondrial DNA--inherited only from our mothers. It can be typed by comparing relatives if no DNA from the body is available. Only the root contains nuclear DNA. *

Hair Morphology The Study of Structure and Form Parts of the hair Shaft--part of the hair that sticks out of the skin Root--lies below the epidermis Follicle--structure from which the hair grows *

Hair Growth Terminology Anagen--hair that is growing Catagen--hair at rest Telogen--hair that is dying Length--00.5 mm per day or 1 centimeter per month; approximately one half inch per month *

Hair Cuticle The cuticle is the outermost layer of hair which is covered with scales. Scales also always point toward the tip of the hair. These scales differ between species of animals and are names based on their appearance. Some of these scales are variations of the same and include: Mosaic Pectinate Imbricate Petal Diamond petal Chevron *

Scale Types Mosaic Chevron *

Scale Types (cont) Pectinate Imbricate *

Scale Types (cont) Petal Diamond Petal *

HUMAN SCALES In order to visualize the scales paint fingernail polish on a slide place a hair on the polish lift off the hair and observe the scale imprints What pattern is seen in this slide? *

Hair Cortex The cortex gives the hair its shape. It has two major characteristics: Melanin--pigment granules that give hair its color Cortical fusi--air spaces, usually found near the root but may be found throughout the hair shaft *

Hair Medulla The medulla is the hair core that is not always present. The medulla comes in different types and patterns. Types: Continuous Intermittent or interrupted Fragmented Absent--not present *

Hair Medulla Patterns Uniserial Multiserial Vacuolated Lattice Amorphous (without a distinct pattern) *

HUMAN MEDULLA Human medulla may be continuous, fragmented or absent. *

Medullary Index Determined by measuring the diameter of the medulla and dividing it by the diameter of the hair. Medullary Index for human hair is generally less than 1/3. For animal hair, it is usually greater than 1/2. *

SUMMARY HAIR STRUCTURE *

Head Hair usually the longest hairs on the human body characterized as having a uniform diameter and, often, a cut tip Alterations to the natural appearance of hair include use of hair dyes, rinses, permanents, frosts, and other chemical applications. Environmental alterations can result from exposure to excessive sunlight, wind, dryness, and other conditions Because these hairs can be affected by a number of environmental and chemical conditions, it is recommended that head hair samples be obtained as soon as possible from suspects and victims of crime. Head hair samples obtained years after a crime are generally not suitable for meaningful comparison purposes *

Pubic Hairs considerable variation exists between individuals in the population Pubic hairs are not subject to as much change as head hairs over time, and because of this, a sample taken a year or more after a crime may still be suitable for meaningful comparison purposes generally coarse and wiry in appearance. They exhibit considerable diameter variation or buckling tapered tips are common, these hairs may also be cut. *

Facial Hairs commonly called beard hairs or mustache hairs These hairs are coarse in appearance and can have a triangular cross section characteristics include a wide medulla and a razor-cut tip. The presence of facial hairs on the clothing of a suspect or victim may help establish contact between these individuals. While these hairs may be compared microscopically, the significance of the association may not be as great as head hair and pubic hair associations. *

Limb Hairs Hairs from the legs and arms constitute limb hairs These hairs are shorter in length, arc- like in shape, and often abraded or tapered at the tips. The pigment in limb hair is generally granular in appearance, and the medulla is trace to discontinuous. While limb hairs are not routinely compared in a forensic laboratory, they can differ in appearance between individuals. These differences, however, are not considered sufficient to allow limb hairs to be of value for meaningful comparison purposes. *

Hair Comparison Color Length Diameter Distribution, shape and color intensity of pigments granules Dyed hair has color in cuticle and cortex Bleaching removes pigment and gives yellow tint Scale types Presence or absence of medulla Medullary type Medullary pattern Medullary index *

Hair and Types of Loss Approximately 100 head hairs are shed every day. Naturally shed hairs, such as a head hair dislodged through combing, display undamaged, club-shaped roots. *

Hair and Types of Loss A hair forcibly removed from the scalp will exhibit stretching and damage to the root area. Forcibly removed hairs may have tissue attached. *

Types of Human Hair by Race Caucasian Negroid Monogloid *

Negroid (African) Hairs of Negroid or African origin are regularly curly or kinky, have a flattened cross section, and can appear curly, wavy, or coiled. Negroid pigment granules are larger than those found in Mongoloid and Caucasian hair and are grouped in clumps of different sizes and shapes. *

Caucasoid (European) Hairs of Caucasoid or Caucasian origin can be of fine to medium coarseness, are generally straight or wavy in appearance, and exhibit colors ranging from blonde to brown to black. The hair shafts of Caucasian hairs vary from round to oval in cross section and have fine to medium-sized, evenly distributed pigment granules. *

Monogoloid (Asian) Hairs of Mongoloid or Asian origin are regularly coarse, straight, and circular in cross section, with a wider diameter than the hairs of the other racial groups. The outer layer of the hair, the cuticle, is usually significantly thicker than the cuticle of Negroid and Caucasian hairs, and the medulla, or central canal, is continuous and wide *

Collection of Hair Evidence Questioned hairs must be accompanied by an adequate number of control samples. from victim possible suspects others who may have deposited hair at the scene Control Sample 50 full-length hairs from all areas of scalp 24 full-length pubic hairs *

Hair Toxicology Advantages: Easier to collect and store Is externally available Can provide information on the individual’s history of drug use. Collections must be taken from different locations on the body to get an accurate timeline. *

HAIR TESTING Procedure Collect an adequate sample, cut as closely to the scalp as possible. Wash the hair to remove lipids, oils, cosmetics and any drugs adhering to it Cut it into one centimeter sections Place hair in a digesting solution Screening test--antibodies are added to the hair that bind with the drugs. If this shows that drugs are present: A confirmation test is done by gas chromatograph and then a mass spectrometer. *

THE END *