Ch3PP.notebook October 03, 2012
Hair is considered class evidence Chapter 3 blonde hair would exclude people with Asian and African The Study of Hair ancestry (can determine if hair has been dyed) By the end of the chapter you will be able to: secondary transfer : hair can adhere to clothes, carpet or other surfaces and then be transferred to other locations. Common with animal hair • identify the various parts of a hair does not easily decompose because of tough outer • describe variations in the structure of the medulla, cortex, covering and cuticle physical characteristics give clues of racial background • distinguish between human and nonhuman hair chemical tests can provide information about drug use, • determine if two examples of hair are likely to be from the toxins, heavy metals, nutritional deficiencies same person only if follicle is attached, can it provide DNA, which would • explain how hair can be used in a forensic investigation be individual evidence • calculate the medullary index for a hair
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History of Hair Analysis • One of first cases to use the investigation of hair was Function of Hair the murder of the Duchesse de Praelsin in Paris in 1847. • A.S.Taylor and T. Stevenson, in 1883, wrote a forensic science text that included a chapter on hair. • V. Balthazard and M. Lambert, in 1910, published a • comprehensive study of hair. Hair on mammals helps to 1) regulate body • Dr. Sydney Smith, in 1934, first used a comparison temperature, 2) decrease friction, 3) protect microscope to analyze hairs side by side. against sunlight and 4) act as a sense organ. comparison microscope compound microscope Fur is simply dense hair. that allows scientists to examine samples sideby • In humans, the temperature regulation function is side, such as hair or fibers. reduced by the lack of hair compared to many • Advances continue today with chemical tests, neutron other mammals (goose bumps) activation analysis, and DNA analysis.
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1. Terms Quiz Monday Structure of Hair secondary transfer cortex • comparison microscope cuticle Hair consists of a hair shaft produced by a follicle hair shaft melanin embedded in the skin. hair follicle imbricate follicle: the actively growing root or base of a papilla neutron activation analysis hair containing DNA and living cells sebaceous gland Taylor & Stevenson keratin Balthazard & Lambert club shaped medulla Dr. Sydney Smith papilla: network of blood vessels at the end of the follicle that supply nutrients to the hair 2. Collect 5 different hair samples human and non sebaceous gland: secretes oil to help keep the human each different hair sample must be in a hair conditioned separate envelope or paper bindle and must be nerve cells wind around the follicle and labeled with its source. Due Monday stimulate muscles in response to changing environments
Oct 67:17 AM Sep 2910:57 AM 1 Ch3PP.notebook October 03, 2012
Structure of Hair continued Structure of Hair continued • • hair shaft is composed of the protein keratin, A hair has three layers: the inner medulla, the cortex, produced in the skin, which makes it strong & flexible and the outer cuticle. (Analagous to a pencil) keratin: type of fibrous protein that makes up Cuticle is the tough outermost layer made of over the majority of the cortex of a hair lapping scales that protect the inner layers of the hair. Cortex is the thickest layer, surrounding the medulla, keratin made of amino acid chain in helix shape containing granules of pigment which give hair its color. distribution of pigment in the cortex varies from person to person. pigment, commonly, is denser nearer the cuticle. melanin: bits of pigment found in the cortex of a hair
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The Cuticle Types of Medulla transparent scales point from proximal end (nearest skin) to the distal end can determine older and younger ends of hair useful when analyzing hair for the presence of different toxins, drugs, etc In humans, scales are flattened and narrow and are also called imbricate Medulla (inner section) can be hollow or filled with cells Patterns: absent, interrupted (intermittent), fragmented (segmented), continuous, or solid It may or may not contain pigment. Hair may contain a double medulla
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Hair from different parts Types of Hair of the body • Different regions of the body on which hair can vary are (1) head, (2) eyebrows and lashes, (3) mustache and beard, (4) underarms, (5) overall body (auxiliary hair), and (6) pubic. Buckled Blunt Double Medulla Cross sections differ • The cross section of a hair can be circular, triangular, 1. head hair is circular or elliptical irregular, or flattened influencing the curl of the hair. 2. eyebrows and eyelashes are circular with tapered ends • Texture of a hair can be coarse or fine. 3. mustache/beard are thick and triangular • Different hairs from one location on a person can vary 4. body/pubic hair is oval or triangular can have just some gray hairs arm & leg hair tend to have blunt ends and could be frayed 50 hairs are usually taken from a suspect's head and, if from abrasion necessary, 25 hairs from the pubic region. beard hair is coarse and may have double medulla buckling may be present in pubic hair
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The Life Cycle of Hair Treated Hair Hair proceeds through 3 stages as it develops:
• During the long anagen stage (~1000 days), hair • Bleaching disturbs the scales on the cuticle and actively grows. The cells around the follicle rapidly removes pigment leaving hair brittle and a yellowish divide and deposit materials in the hair. color. 8090% of all human hair is in this stage artificial shows sharp demarcation while • catagen stage, the hair grows and changes. In the sun bleaching shows a more gradual ~2% of all hair growth and development mark • Hair is in the telogen stage when the follicle becomes • Dyeing colors both the cuticle and the cortex of the dormant. During this stage, hairs easily can be lost. hair shaft. 1018% are in this stage dye is recognizable as unnatural to • No pattern as to which hairs on the head are in a experienced forensic scientists particular stage at any time
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• Hair grows on average 1.3 cm per month (.44 Racial mm/day) Differences measuring the length of hair and dividing by 1.3 cm provides you with an approximation of the # of months since the hair was • Hair examiners have identified some physical colored. characteristics that can be associated with broad, • Because of this and because hair grows daily, a racial groups. person’s treated hairs will have specific characteristics • These characteristics, however, will not apply to all in common with her or his lost hairs. individuals in these groups. • In addition, at times, it will be impossible to assign specific hairs to any of these groups because their characteristics are poorly defined or hard to measure. • See Figure 310
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Animal Hair and Human Hair Animal Hair and Human Hair
• animal hair pigment is denser toward the medulla. In humans it is denser toward the cuticle. Spinous Coronal Imbricate • animal pigments are often in solid masses called The outermost layer of the hair shaft (the cuticle), is ovoid bodies, especially in dogs and cattle typically different in animals and humans. • Unlike human hair, animal hair can abruptly change • The cuticle scales in animals (cats, seals, and mink) colors in banded patterns along the length of hair. tend to resemble petals (spinous) or they give the • The medullary index in animals is much thicker. appearance of a stack of crowns (coronal), like in medullary index: ratio of diameter of the medulla rodents and bats. • to the diameter of the entire hair The cuticle scales in humans commonly are flattened if index is 0.5 or greater, the hair came from an and narrow (imbricate). animal, if it is 0.33 or less it is human hair.
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Specialized techniques • Phase contrast microscopy observes fine detail. focuses light that passes through objects of Using Hair in an different refractive indexes. Investigation shows more contrast when viewing translucent particles • Fluorescence microscope filters to detect fluoresced light. • Macroscopic investigation can indicate length, color, beam of light of a certain color is used, if sample and curliness. contains particular chemicals it will absorb some of • Microscopic investigation can indicate fine detail in the light and reemit light of a different color. can show the presence of dye or other treatments. hair structure. • Electron microscopes direct beam of electrons at a pattern of medulla, pigmentation of cortex, types of scales, medullary index sample. typical magnification is 40X 400X provide more detail of the surface or interior (50,000X). In the sample below, note the overlapping scales and the pigment granules in the cortex.
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• Neutron Activation Analysis (NAA) can determine Testing for Substances in concentrations of substances in the sample. the Hair Shaft can identify 14 elements in a 2 cm strand hair placed in a nuclear reactor and elements will give off different gamma ray signals • Chemicals that the skin absorbs often can be identifies antimony, argon, bromine, copper, gold, detected by analysis of the hair shaft. manganese, silver, sodium, and zinc • During testing hair is dissolved in an organic probability of two individuals having the same solvent that breaks down keratin and releases any concentration of 9 different elements is about one substances that are in the hair. in a million. • • The hair shaft can be examined in sections to Useful if you don't have the follicle. establish a timeline for exposure to toxins.
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Testing the Hair Follicle • Microscopic assessment of the follicle is performed Summary first because it is cost effective and quick.
• If a microscopic match is found between a suspect and • Hair consists of a (a) hair shaft produced by a (b) a sample then the sample will be forwarded for blood and follicle embedded in the skin. DNA testing • The shaft consists of an outer cuticle, a cortex, and an • If hair is forcibly removed and the entire hair follicle is inner medulla. present it is called follicular tag. (blood & tissue) • Various hair treatments produce characteristic effects The follicle can be blood tested and perhaps show useful to forensic experts. the blood type. • Some characteristics allow them to be grouped into The follicle can also be DNA analyzed to provide general racial categories. identification with a high degree of confidence. • Forensic experts examine hair using chemicals, light, electrons, neutrons, and DNA sequencing.
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