Forensic Hair AnalysisForensic Hair Analysis

What is it good for?What is it good for?

What is it good for?What is it good for?

Identifying criminal suspectsIdentifying criminal suspects Identifying crime victimsIdentifying crime victims Associating a victim or suspect with a Associating a victim or suspect with a

locationlocation Determining the type of crime Determining the type of crime

committedcommitted

Significance of Hair Evidence Significance of Hair Evidence ExaminationsExaminations

Hairs can be transferred during physical Hairs can be transferred during physical contact, their presence can associate a contact, their presence can associate a suspect to a victim or a suspect/victim to a suspect to a victim or a suspect/victim to a crime scene. crime scene.

The types of hair recovered and the condition The types of hair recovered and the condition and number of hairs found all impact on their and number of hairs found all impact on their value as evidence in a criminal investigation. value as evidence in a criminal investigation.

Comparison of the microscopic characteristics Comparison of the microscopic characteristics of questioned hairs to known hair samples of questioned hairs to known hair samples helps determine whether a transfer may have helps determine whether a transfer may have occurred occurred

Significance of Hair Evidence Significance of Hair Evidence ExaminationsExaminations

Nothing about hair is comparable to the Nothing about hair is comparable to the specificity of fingerprints; probability of specificity of fingerprints; probability of establishing identification from hair is establishing identification from hair is similar to determining identification using similar to determining identification using the ABO blood group system the ABO blood group system

However, Research studies have shown However, Research studies have shown that hairs from two individuals are that hairs from two individuals are distinguishable; that no accidentaldistinguishable; that no accidentalor coincidental matches occurred or coincidental matches occurred

Significance of Hair Evidence Significance of Hair Evidence Examinations, cont’dExaminations, cont’d

Hair evidence is only of value when used in Hair evidence is only of value when used in conjunction with other evidenceconjunction with other evidence

Positive hair comparison conclusions:Positive hair comparison conclusions: weakened by the presence of incomplete hairs; weakened by the presence of incomplete hairs;

by common, featureless hairs; and by known by common, featureless hairs; and by known samples with large intrasample variation. samples with large intrasample variation.

strengthened by the presence of two or more strengthened by the presence of two or more mutually dissimilar hairs that are similar to a mutually dissimilar hairs that are similar to a known sample; by hairs with unusual known sample; by hairs with unusual characteristics; by two-way transfers; and by characteristics; by two-way transfers; and by additional examinations of confirmation, such additional examinations of confirmation, such as DNA and sex-typing.as DNA and sex-typing.

Significance of Hair Evidence Significance of Hair Evidence Examinations, cont’dExaminations, cont’d

Negative hair comparison conclusions:Negative hair comparison conclusions: weakened by deficiencies in the known hair weakened by deficiencies in the known hair

sample, including too few hairs, sample, including too few hairs, unrepresentative hairs, incomplete hairs, and a unrepresentative hairs, incomplete hairs, and a significant temporal difference between the significant temporal difference between the offense and the collection of the known sample offense and the collection of the known sample

strengthened by a large quantity of known strengthened by a large quantity of known sample hairs; little intrasample variation within sample hairs; little intrasample variation within the known sample; and hairs that are very the known sample; and hairs that are very dissimilar, such as those exhibiting distinct dissimilar, such as those exhibiting distinct racial and/or microscopic characteristics racial and/or microscopic characteristics

Basics of Hair EvidenceBasics of Hair Evidence Hairs are composed primarily of the protein Hairs are composed primarily of the protein

keratinkeratin, , can be defined as slender outgrowths of can be defined as slender outgrowths of the skin of mammals. the skin of mammals.

Each species of animal possesses hair with Each species of animal possesses hair with characteristic length, color, shape, root characteristic length, color, shape, root appearance, and internal microscopic features appearance, and internal microscopic features that distinguish one animal from another. that distinguish one animal from another.

Considerable variability also exists in the types of Considerable variability also exists in the types of hairs that are found on the body of an animal. hairs that are found on the body of an animal. In humans, hairs found on the head, pubic region, In humans, hairs found on the head, pubic region,

arms, legs, and other body areas have characteristics arms, legs, and other body areas have characteristics that can determine their origin. On animals, hair types that can determine their origin. On animals, hair types include coarse outer hairs or guard hairs, the finer fur include coarse outer hairs or guard hairs, the finer fur hairs, tactile hairs such as whiskers, and other hairs hairs, tactile hairs such as whiskers, and other hairs that originate from the tail and mane of an animal. that originate from the tail and mane of an animal.

Hair MicroscopyHair Microscopy examination of human hairs in the examination of human hairs in the

forensic laboratory is typically forensic laboratory is typically conducted through the use of light conducted through the use of light microscopy microscopy

two-step process—the identification two-step process—the identification of questioned hairs and the of questioned hairs and the comparison of questioned and known comparison of questioned and known hairs using comparison microscopyhairs using comparison microscopy

Hair DiagramHair Diagram

Hair Anatomy & GrowthHair Anatomy & Growth Hair growth stages:Hair growth stages:

Anagenic: hair follicle is actively Anagenic: hair follicle is actively producing the hair; follicle is attached to producing the hair; follicle is attached to the rootthe root

Catagenic: transition stage in which the Catagenic: transition stage in which the root is pushed out of the follicleroot is pushed out of the follicle

Telogenic: hair naturally becomes loose Telogenic: hair naturally becomes loose and falls outand falls out

Hair and types of lossHair and types of loss

Naturally shed hairs, such as a Naturally shed hairs, such as a head hair dislodged through head hair dislodged through combing, display undamaged, combing, display undamaged, club-shaped roots.club-shaped roots.

Cont’dCont’d A hair forcibly removed from the A hair forcibly removed from the

scalp will exhibit stretching and scalp will exhibit stretching and damage to the root area.damage to the root area.

Forcibly removed hairs may have Forcibly removed hairs may have tissue attached.tissue attached.

Animal HairsAnimal Hairs

Human Cat Dog Mouse

Animal HairsAnimal Hairs

animal hairs do not possess enough animal hairs do not possess enough individual microscopic characteristics to be individual microscopic characteristics to be associated with a particular animal to the associated with a particular animal to the exclusion of other similar animals exclusion of other similar animals

If the questioned hair exhibits the same If the questioned hair exhibits the same microscopic characteristics as the known microscopic characteristics as the known hairs, it is concluded that the hair is hairs, it is concluded that the hair is consistent with originating from that consistent with originating from that animal animal

CatCat

RabbitRabbit

RabbitRabbit

Cuticle Cuticle Pattern >Pattern >

DeerDeer

HumanHuman

500500

Ovoid bodies found in Dog Ovoid bodies found in Dog HairHair

Ovoid bodies are abundant Ovoid bodies are abundant in Cattle hairin Cattle hair

Human HairsHuman Hairs physical contact may result in the transfer of physical contact may result in the transfer of

hairshairs primary transfer— transfer directly from the primary transfer— transfer directly from the

region of the body where they are growingregion of the body where they are growing Secondary transfer—transfer from the clothing of Secondary transfer—transfer from the clothing of

individuals. individuals. approximately 100 head hairs are shed by an approximately 100 head hairs are shed by an

individual each day. individual each day. Contact between a victim and a suspect's Contact between a victim and a suspect's

environment can easily cause a secondary environment can easily cause a secondary transfer of hair. Hairs that are found on the transfer of hair. Hairs that are found on the clothing of suspects or victims and appear to clothing of suspects or victims and appear to have fallen out naturally may be the result of have fallen out naturally may be the result of primary or secondary transfer. Hairs that have primary or secondary transfer. Hairs that have been forcibly removed may suggest a violent been forcibly removed may suggest a violent confrontation confrontation

Types of Human Hair by Body Types of Human Hair by Body AreaArea

The body area from which a hair The body area from which a hair originated can be determined by originated can be determined by general morphology. Length, shape, general morphology. Length, shape, size, color, stiffness, curliness, and size, color, stiffness, curliness, and microscopic appearance all microscopic appearance all contribute to the determination of contribute to the determination of body area body area

Head HairHead Hair usually the longest hairs on the human bodyusually the longest hairs on the human body characterized as having a uniform diameter and, characterized as having a uniform diameter and,

often, a cut tip often, a cut tip Alterations to the natural appearance of hair Alterations to the natural appearance of hair

include use of hair dyes, rinses, permanents, include use of hair dyes, rinses, permanents, frosts, and other chemical applications. frosts, and other chemical applications. Environmental alterations can result from Environmental alterations can result from exposure to excessive sunlight, wind, dryness, exposure to excessive sunlight, wind, dryness, and other conditions and other conditions

Because these hairs can be affected by a number Because these hairs can be affected by a number of environmental and chemical conditions, it is of environmental and chemical conditions, it is recommended that head hair samples be recommended that head hair samples be obtained as soon as possible from suspects and obtained as soon as possible from suspects and victims of crime. Head hair samples obtained victims of crime. Head hair samples obtained years after a crime are generally not suitable for years after a crime are generally not suitable for meaningful comparison purposes meaningful comparison purposes

Razor cut hairRazor cut hair

Split hairSplit hair

Hair with cut tipHair with cut tip

Pubic HairsPubic Hairs considerable variation exists between considerable variation exists between

individuals in the population individuals in the population Pubic hairs are not subject to as much Pubic hairs are not subject to as much

change as head hairs over time, and change as head hairs over time, and because of this, a sample taken a year or because of this, a sample taken a year or more after a crime may still be suitable for more after a crime may still be suitable for meaningful comparison purposes meaningful comparison purposes

generally coarse and wiry in appearance. generally coarse and wiry in appearance. They exhibit considerable diameter They exhibit considerable diameter variation or buckling variation or buckling

tapered tips are common, these hairs may tapered tips are common, these hairs may also be cut. also be cut.

Facial HairsFacial Hairs

commonly called beard hairs or mustache hairscommonly called beard hairs or mustache hairs These hairs are coarse in appearance and can These hairs are coarse in appearance and can

have a triangular cross sectionhave a triangular cross section characteristics include a wide medulla and a characteristics include a wide medulla and a

razor-cut tip.razor-cut tip. The presence of facial hairs on the clothing of a The presence of facial hairs on the clothing of a

suspect or victim may help establish contact suspect or victim may help establish contact between these individuals. While these hairs between these individuals. While these hairs may be compared microscopically, the may be compared microscopically, the significance of the association may not be as significance of the association may not be as great as head hair and pubic hair associations.great as head hair and pubic hair associations.

Limb HairsLimb Hairs Hairs from the legs and arms constitute limb hairsHairs from the legs and arms constitute limb hairs These hairs are shorter in length, arc-like in These hairs are shorter in length, arc-like in

shape, and often abraded or tapered at the tips. shape, and often abraded or tapered at the tips. The pigment in limb hair is generally granular in The pigment in limb hair is generally granular in appearance, and the medulla is trace to appearance, and the medulla is trace to discontinuous.discontinuous.

While limb hairs are not routinely compared in a While limb hairs are not routinely compared in a forensic laboratory, they can differ in appearance forensic laboratory, they can differ in appearance between individuals. These differences, however, between individuals. These differences, however, are not considered sufficient to allow limb hairs to are not considered sufficient to allow limb hairs to be of value for meaningful comparison purposes. be of value for meaningful comparison purposes. The presence of leg or arm hairs on certain items The presence of leg or arm hairs on certain items of evidence may help to corroborate other of evidence may help to corroborate other investigative information.investigative information.

Types of Human Hair by Types of Human Hair by RaceRace

Caucasian Negroid Mongloid

Negroid (African)Negroid (African)

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

Caucasoid (European)Caucasoid (European)

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

Mongoloid (Asian)Mongoloid (Asian)

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

Human Hairs to Determine Human Hairs to Determine AgeAge

The age of an individual cannot be The age of an individual cannot be determined definitively by a microscopic determined definitively by a microscopic examination; examination;

the microscopic appearance of certain the microscopic appearance of certain human hairs, such as those of infants and human hairs, such as those of infants and elderly individuals, may provide a general elderly individuals, may provide a general indication of age. indication of age.

i.e. The hairs of infants are generally finer i.e. The hairs of infants are generally finer and less distinctive in microscopic and less distinctive in microscopic appearance. As individuals age, hair can appearance. As individuals age, hair can undergo pigment loss and changes in the undergo pigment loss and changes in the configuration of the hair shaft to become configuration of the hair shaft to become much finer and more variable in diameter. much finer and more variable in diameter.

Human Hairs to determine Human Hairs to determine sexsex Although the sex of an individual is difficult Although the sex of an individual is difficult

to determine from microscopic examination, to determine from microscopic examination, longer, treated hairs are more frequently longer, treated hairs are more frequently encountered in female individuals.encountered in female individuals.

Sex can be determined from a forcibly Sex can be determined from a forcibly removed hair (with tissue), but this is not removed hair (with tissue), but this is not routinely done. Definitive determination of routinely done. Definitive determination of sex can be accomplished through the sex can be accomplished through the staining of sex chromatin in the cells found staining of sex chromatin in the cells found in the follicular tissue, but nuclear DNA and in the follicular tissue, but nuclear DNA and mitochondrial DNA (mtDNA) tests will mitochondrial DNA (mtDNA) tests will provide more specific information regarding provide more specific information regarding the possible origin of the hair. the possible origin of the hair.

Cont’dCont’d

Stained sex chromatin in the Stained sex chromatin in the nuclei of human cells showing nuclei of human cells showing the female-indicative Barr body the female-indicative Barr body (bright spot, left) and the male-(bright spot, left) and the male-indicative Y body (bright spot, indicative Y body (bright spot, right)right)