excited at the moment something s happening like people do. t sits there and wafts to be --Herbert Leon MacDoneli, The Evidence NeverLies inner medulla, the cortex, and the outer cuticle. A hair has three layers (illustrated above): the Structure of Hair The Function and certaml may lie Even the judge may lie. Only attorneys may lie, witnesses may lie,the defendant ntimidated. t does not forget. t doesn t get This s what physical evidence s all about n the You can lead a jury to the truth but you can t make them believe it. Physical evidence cannot be course of the trial, defense and prosecuting the evidence never lies. detected, preserved, evaluated and explained. JKi3ic,4 (b) a follicle embedded in the skin. Hair consists of (a) a hair shaft produced by temperature, decrease friction, and protect against sunlight. Hair on mammals helps to regulate body 4L1 *fr4t17?.:
between the criminal and the act. violent crime. t can provide a link found pieces of evidence at the scene of a From hair one can determine: ki.&mu c r the cuticle, medulla, and cortex. Hair can be defined as a slender, thread-like outgrowth mainly of keratin, it has three morphological regions from a follicle in the skin of mammals. Composed dp C$dbOc cottex -. cu:ic fl 1ingested anner in which hair was removed Origin hair Human hair is one of the most frequently J(air
http://wwwdbi.gov/hq/ab/fsc/backissu/july2004/research/2004_03_researcho2.htm Manual for Animal Hairs Microscopy of Hair Part : A Practical Guide and _ lies below Parts of the hair The Stud3 ofst7ulurj anafoi,, J/air9vlorphofogy structure from which the hair grows _--partofthehajr the epidermis that sticks out ofthe skin
4 pigment giving hair its color. Pigment, commonly, is denser nearer the cuticle. person to person. The distribution of pigment in the cortex varies from The Cuticle is the outermost layer made of over The Cortex is the thickest layei containing most of the lapping scales that protect the inner layers of the hair. Tb. OuRr 2 L.e. Types of Cutkle and Cortex of growth, the hair remains in the follicle in a resting stage to eventually be sloughed from the body. These elements are deposited in the hair during its growth and/or absorbed by the hair from an external environment. After a period to form the root bulb. ts basic components are keratin (a protein), melanin (a pigment), and trace quantities of metallic elements. shaft that projects above the skin and a root that is iinbedded in the skin. Figure 83 diagrams how the lower end of the root expands A hair grows from the papilla and, with the exception of that point of generation, is made up of dead, cornified cells. t consists of a ca1ary sdcar%eous ttss4
Anim Hair and Human Hair Sprnoi Coror The outermost layer of the hair shaft (the cutide), is typically different - The animals and humans. cuticle scales animals tend to resemble petals in in (spinous) or they give the appearance of a stack of crowns (coronal). - The cuticle scales in and narrow (imbricate), humans commonly are flattened The cuticle is a translucent outer layer of the hair shaft consisting of scales that cover the shaft. Figure 84 illustrates how the cuticular scales always point from the proximal or root end of the hair to the distal or tip end of the hair. The coronal, or crown-like scale pattern, is found in hairs of very fine diameter and resemble a stack of paper cups. Coronal scah are commonly found in the hairs of small rodents and bats but rarely in human hairs. Figure 85 is a diagram depicting a longitudinal view of coronal scales, and Figure 86 is a photomicrograph of a free-tailed bat hair. %-* Photomicrograph of Free-Tailed Bat Hair
The imbricate or flattened-scale type consists of overlapping scales with narrow margins. They are commonly found in human hair and many animal hairs. Figure 89 is a diagram of imbricate scales, and Figure 90 is a photomicrograph of the distal-scale pattern ii mink hairs.
pigmented, or un- pigmented. - and w spiød Fwqa,a*4 1ks (btutn# c**_ Medulla %1b1efl Zii Types of w*. hairs. Figure 94 exhibits a lattice found in deer family hairs. the structure appears clear or translucent in transmitted light, or nearly invisible in reflected light. n human hairs, the medulla is under transmitted light, or as a white structure under reflected light. f it is filled with mounting medium or some other clear substan generally amorphous in appearance, whereas in animal hairs, its structure is frequently very regular and well defined. Figures 91 through 94 are photoniicrographs of medullary types found in animal hairs. Figure 91 exhibits a uniserial ladder, and Figure 92 The medulla is a central core of cells that may be present in the hair. f it is filled with air, it appears as a black or opaque structure exhibits a multiserial ladder, both found in rabbit hairs. Figure 93 exhibits the cellular or vacuolated type common in many animal!r $ru filled, absent, fragmented, continuous, doubled, The medulla (the inner section) can be hollow or? [ p1.m,n*.n...f hi id P,ni.d u
hair), and (6) pubic. and beard, (4) underarms, (5) overall body (auxiliary are () head, (2) eyebrows and lashes, (3) mustache Different regions of the body on which hair can vary The texture of a hair can be coarse or fine. irregular, or flattened inftuencingthe curl of the hair The cross section of a hair can be circular, triangular, Types of Hair continuous. Figure 95 is a diagram depicting the three basic medullary types. When the medulla is present in human hairs, its structure can be described as fragmentary or trace, discontinuous or broken, or
17 Pigment granules are small, dark, and solid structures that are granular in appearance and considerably smaller than cortical fusi. toward the medulla, as shown in Figure 99 Photomicrograph of Pigment Distribution in Animal Hair shown in Figure 97, except in red-haired individuals as in Figure 98. Animal hairs have the pigment granules commonly distributed hair, although they may be present throughout the length of the hair. pigment granules, and/or large oval-to-round-shaped structures called ovoid bodies. The cortex is the main body of the hair composed of elongated and fusiform (spindle-shaped) cells. t may contain cortical fusi, Cortical fusi in Figure 96 are irregular-shaped airspaces of varying sizes. They are commonly found near the root of a mature huma They vary in color, size, and distribution in a single hair. n humans, pigment granules are commonly distributed toward the cuticle
:4 The Life Cycle of -fair Haw proceeds through 3 stages as it develops: 1. During the long anagen stage, hair actively grows. The cells around the follicle rapidly divide and deposit materials in the hair. 2. n the catagen stage, the hair grows and changes. 3. Hair is in the telogen stage when the follicle becomes dormant During this stage, hairs easily can be lost. growing resting dying g -:t *atl Treat1 Kair Forensic investigators sometimes can link hair from a location with an individual. Bleaching disturbs the scales on the cuticle and removes pigment leaving hair brittle and a yellowish color. - Dyeing colors the cuticle and the cortex of the hair shaft.. Because of this and because hair grows daily, a person s treated hairs will have specific char acteristics in common with her or his lost hairs. 87
Racial flifferences Hair examiners have identified some physical characteristics that generally can be associated with broad, racial groups. These characteristics, however, will not apply to all individuals in these groups. a in addition, at times, it will be impossible to assign specific hairs to any of these groups be cause their characteristics are poorly defined or hard to measure. e t%* cel Anm Hair arid Human Hair Al Core the rnedii Thk *nyer the co the Pigmentation in animal hair s denser toward the medulla. n Humans it tends to be denser toward the cuticle, Unlike human hair, animal hair abruptly can change colors in banded patterns. The meduilary index s different. n animals the medulla is much thicker than it is in humans.
the sample. determine concentrations of substances in & Neutron Activation Analysis (NAA) can establish a timeline for exposure to toxins. 2. 3. The hair shaft can be examined in sections to tests for the presence of various substances. granules in the cortex. above, note the overlapping scales and the pigment surface Of interior of the sample. n the sample microscopes can provide more detail of the A forensic scientist can perform chemical detected by analysis of the hair shaft. 1. Chemicals that the skin absorbs often can be Testing for 3ubstces in the Hair 3haff & Electron the presence of dye or other treatments. Phase contrast microscopy, for example, can show structure. Microscopic investigation can indicate fine detail in hair Macroscopic investigation can indicate length, color, nvestigation UsngHairinan and curliness.
tint pigment and gives yellow Dyed hair has color in Bleaching removes cuticle and cortex pigments granules Meduliary type Meduilary index Meduflary pattern color intensity of Distribution, shape and absence of medulla + Diameter Presence or Color Length Scale types JlEairCornpaflson 3 Cf r- t*l &t&lw1 a high degree of confidence. - f type. be blood tested and perhaps showthe blood be DNA analyzed to provide identification with - f a microscopic match is found, the follicle can a microscopic match is found, the follicle can quick. performed first because it is cost effective and Microscopic assessment of the follicle is Testwig the Hair Foliwle
, victim general racial categories Some characteristics allow them to be grouped into Forensic experts examine hair using chemicals, light, electrons, neutrons, and DNA sequencing. S The shaft consists of an outer cuticle, a cortex, and effects useful to forensic experts. fill-length hairs from all areas ofscalp Various hair treatments produce characteristic an inner medulla. Hair consists of a (a) hair shaft produced by a (b) follicle embedded in the skin. Surrr1t1ar,, suspects who may have depositedhair at the scene Control Sample cotthaion ofjfair!evitfeiwe 24 fill-length pubic hairs from possible others 50 Questioned hairs must be accompanied by an adequate number of control samples.