PLEASE DO NOW #4 How many hairs does the average person have on his/her head? a) All b) Red hair c) Blond hair d) Brown hair ~100,000 ~90,000 ~140,000 Between 90,000 to 140,000 PLEASE DO NOW #5 Why do humans have hair?
Hair as Evidence Continually falls from the body About 20 to 100 hairs fall out each day Not readily lost or displaced Goes unnoticed by criminal Not easily destroyed Useful associative evidence since it originates directly from the individual
Collection of Hair Evidence The search for and collection of hair evidence should begin as soon as possible. Hair evidence is easily transferred to and from the crime scene. Collection should be done by hand if the location of the hair is important, which is usually the case. Sticky tape and lint rollers may be used to assist. A special filtered vacuum cleaner may be used to collect hairs and fibers en masse from carpet, bedding, etc. If the evidence is stuck to another object, the entire object should be packaged and labeled. Evidence Collecting Vacuum Evidence Collecting Kit
Collection of Hair Evidence Once collected, the hair evidence should be packaged into paper packets. If sticky tape or a lint roller are used, the entire surface used should be packed into a polyethylene storage bag easy to see through, but with no direct contact. Control samples need to be collected from the victim, suspect, and other individuals who could have left evidence at the scene. Take from all pertinent regions of the body; 50 head hairs, 24 pubic hairs. Root still in tact is preferable. Evidence Collection Bags Evidence Collecting Lint Roller
Forensic Analysis of the Hairs Somatic regions can be determined based on the hair s morphology, such as: Head hairs have a soft texture, cut or split tips, and moderate shaft diameter. Pubic hairs have a course, wiry texture, tapered, rounded, or abraded tips, and a buckling shaft. Facial hairs have a triangular cross-section and a course in texture. Eyelash/Eyebrow hairs are saber-like in appearance, short, and stubby. Limb hairs are soft, and arclike in appearance. Tips are rounded and abraded; scales rounded due to wear. Pubic Hair Head Hair Beard Hair
Forensic Analysis of the Hairs Using a microscope (SEM), forensic scientists can typically determine the species, race, and somatic origin of a hair. They may use comparative microscopy to do one of the following: Link the suspect to a crime scene, meaning that a control hair matches the evidential hair. Exclude the suspect from a crime scene, meaning that a control hair does not match the evidential hair. In addition to comparing hairs in with a microscope, the scientists may test for DNA on the follicular tag, and run a number of tests for drugs and environmental toxins, which will be described at length. Scanning Electron Microscope, a typical device used to study the structures of hair.
Forensic Analysis of the Hairs Hair analysis is used in forensic toxicology to test and determine whether a drug was used. When a drug is ingested, it enters the blood stream and is broken down to a specific metabolite. Hair strands normally grow at an average rate of 1.3 centimeters every month; they absorb metabolized drugs that are fed to the hair follicle through the blood stream. The drug will only disappear if exposure to the drug is ceased, and the hair containing the drug is cut. Hair analysis can be used for the detection of many therapeutic drugs and recreational drugs, including cocaine, heroin, benzodiazepines (Valium-type drugs) and amphetamines. Depicting how drugs enter the hair. Cocaine s Structure General structure for amphetamines.
Forensic Analysis of the Hair The radioimmunoassay and enzyme-linked immunosorbent assay are two common assays that are used by forensic toxicologists to detect substances such as drugs in the hair. Recall that the immunoassays function on the basis of an antigenantibody interaction. The analyte, or drug, is added and binds to the solid phase, typically producing a color change, fluorescence, etc. that can be measured to determine the amount of drug present. Forensic toxicologists also look for toxic metals in the hair to explain poor mental and physical health. How an ELISA functions
Forensic Analysis of the Hair Individualization has been impossible to obtain with hairs in the past, but recent techniques are making it more realistic. Nuclear DNA (ndna) and mitochondrial DNA (mtdna) can be extracted from the root or follicular tag of an anagenic hair. Nuclear DNA comes from both parents; mitochondrial DNA is passed only from mother to offspring. Nuclear DNA can lead to individualization. Odds created by association of a suspect with evidential hairs are typically one to billions or trillions. DNA Smear of anagenic hair
Hair in Forensics It is important to note that it is impossible for experts to individualize a hair (in other words, match it perfectly to any single head/ body) Hair samples can be used to place an individual at a location by comparing hair recovered from the crime scene with control samples
1. Alfred Swaine Taylor and Thomas Stevenson, in 1883, wrote a forensic science text that included a chapter on hair. 2. Victor Balthazard and Marcelle Lambert, in 1910, published a comprehensive study of hair. 3. Dr. Sydney Smith, in 1934, first used a comparison microscope to analysis hairs side by side. 4. Advances continue today with chemical tests, neutron activation analysis, and DNA analysis. 11
12 Hair on mammals helps to regulate body temperature, acts as a filter in nose and ears, and protect against sunlight.
Hair Morphology (Structure) Feature unique to mammals Composed primarily of keratin Hair consists of (a) a hair shaft produced by (b) a follicle embedded in the skin. Root = portion of hair that lies in follicle Bulb = enlarged base of root Dermal papilla = connective tissue surrounded by bulb Shaft = connects with the root; portion of hair above skin s surface ends with the tip
Hair Morphology (Structure) The shaft of the hair has 3 layers Cuticle = thin translucent scale layer surrounding shaft Cortex = main body of hair shaft Medulla = central canal-like structure
Cuticle Made up of overlapping, nonnucleated, pigment-free, keratinized cells that have formed scales As many as 6 layers of scales per hair Scales always point away from the root Allows the hair to retain structural features and resist chemical decomposition Outer and inner cuticle margins can be: Cracked Ragged Serrated Flattened
Cuticle margins
Cuticle Scale pattern useful for species identification Viewing cuticle scales Mount hair between glass slides Prepare a clear cast of the cuticular surface Scanning electron microscope
Cortex Composed of elongated keratinized filaments aligned together parallel to the length of the hair Contained within cells of cortex Cortical fusi = delicate air spaces Vary in amount, size, shape and distribution Appear dark with transmitted light and bright with direct light Hair pigment = solid structure that gives hair color Vary in size, shape, distribution and density (usually denser nearer the cuticle in humans) Appear dark and granular Smaller than cortical fusi Ovoid bodies Solid structures that are oval in shape Larger than pigment granules
Cortex
Cortex Cortical fusi in human hair (air spaces of varying sizes found near the root of mature human hair) Ovoid body
Cortex
Types of Medulla 23 The medulla (the inner section) can be hollow or filled, absent, fragmented, continuous, doubled, pigmented, or un- pigmented.
Medulla Cellular column running through the center of the cortex Function is to increase protective properties of hair by adding internal space Medulla structure on humans is amorphous Pattern can be absent, fragmental, interrupted, or continuous Appearance will vary from person to person and within hairs of the same individual (trace) (discontinuous)
Medulla central canal running the length of the hair interrupted absent continuous
Medulla Human hair with no medulla Clear, continuous medulla trace (fragmented) medulla
Medullary Index = diameter of medulla diameter of the hair shaft The medullary index is different in animals the medulla is much thicker than it is in humans Humans have a MI of ⅓ or less Animals have a MI of ½ or greater.
Hair Roots The hair root allows for the growth of the hair There are three phases of root development: Anagen, Catagen, and Telogen Each root phase has a different shape and size
Root Development
Buckled Blunt Double Medulla The cross section of a hair can be circular, triangular, irregular, or flattened influencing the curl of the hair. The texture of a hair can be coarse or fine. 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. 30
Treated Hair 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 characteristics in common with her or his lost hairs. 31
Hair Growth Average period of hair growth 1,000 days Grows 1 cm (~1/2 inch) per month 3 distinct growth phases Anagen - growth phase (80-90% of hairs) Follicle actively producing hair Catagen - transitional phase (2% of hairs) Transitional period Telogen resting phase (10-18% of hairs) Follicle dormant/resting
The Life Cycle of Hair Hair 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. In 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. 33
Hair Growth 1. Anagen Phase Can last up to 6 years Cells in dermal papilla undergo mitosis and grow up to form hair shaft Follicle is attached to the root by the dermal papilla Forcibly removed roots in the anagen phase may have a piece of DNA attached known as a follicular tag (can be used to test for DNA) Bulb is described as flame shaped
Hair Growth 2. Catagen Phase Lasts only 2-3 weeks Elongated appearance as the root is gradually being forced out of the hair follicle Hair keeps growing but the bulb of the root shrinks and becomes surrounded by the club a capsule of cells
Hair Growth 3. Telogen Phase Lasts 2-6 months, during which time hair growth has completely stopped Hair anchored in follicle only by club becomes naturally loose and sheds Germ cells below club getting ready to form next hair Dermal papilla looks like a ball below germ cells waiting to be surrounded by next bulb
Hair as Evidence Class evidence Have to compare evidence against reference samples To collect samples: Bright light aids in the visualization of questioned hairs at a crime scene Stored in paper packets or between sealed glass slides Wide transparent tape obtains difficult to see hairs from clothing and carpets Note location from where collected To collect reference samples: Collected from both victim and suspect About 50 samples collected for comparison Should be combed and pulled to represent all growth stages Should be taken from each region of the area Must represent any chemically treated areas of the hair
Identification of Human Hair First step in the forensic investigation of human hair is to identify the hair in question in the following categories: Species Origin Racial Origin Somatic Origin (what part of the body) A direct comparison with a reference hair can only be made after the hair is classified in this way
Species Origin 3 Types of Animal Hairs Vibrissa Tactile and sensitive whiskers Largest and longest hairs on body usually Bristle/Guard Coarse hairs that make up the protective outer coat Distinctive in appearance and morphology between different animal families Wool/Fur Fine short hairs that cover the body and make up the inner coat Provides insulation from wet and cold
Species Origin 4 Types of Human Hairs Primordial Coarse and whisker like Appear during 3 rd month of gestation Grow on upper lips, eyebrows, palms and soles of fetus Lanugo Fine, soft, unmedullated and unpigmented Replace primordial hairs but shed after 6 months of gestation Vellus Fine, soft, unmedullated and short (2 cm) Spread uniformly over body surface except for palms, soles, lips, and nipples Terminal Replace vellus hairs at specific sites and stages of life Scalp and eyebrows, pubic areas, face, chest, back, arms and legs
Species Origin Cuticle Human Imbricate scales = scales are small, flattened and with little serration Animal Exhibit a wide range of cuticular patterns Imbricate scales ( flattened ) Spinous scales ( petal-like ) Coronal scales ( crown-like )
Species Origin - Cuticle Human Hair Imbricate Scales Mink Hair Spinous Scales Bat Hair Coronal Scales
Species Origin Cortex Human Untreated human hair is uniform in color Pigmentation granules are evenly distributed or slightly more dense toward cuticle Animal Hairs exhibit rapid color changes along the shaft called banding Pigmentation granules are more dense toward the medulla
Species Origin - Cortex Pigment Distribution in Human Hair Pigment Distribution in Animal Hair
Species Origin Medulla Human Less than 1/3 width of hair shaft Structure is amorphous Pattern can be absent, fragmented, interrupted, or continuous Animal More than 1/2 width of hair shaft Distinct medulla structure between species
Species Origin - Medulla Uniserial and Multiserial Ladder Medulla in Rabbit Hairs Vacuolated Medulla in Dog Hair Lattice Medulla in Deer Hair
Racial Origin Diameter Cross Section Pigmentation Cuticle Undulation Caucasian70-100 µm Oval Even Medium Uncommon Asian 90-120 µm Round Dense Thick Never African American 60-90 µm Flat Dense and Clumped - Prevalent
Racial Origin
Caucasian Hair Straight to wavy. Fine fairly evenly distributed pigment. Moderate shaft diameter, with little variation. Oval cross-section
Mongoloid (Asian) Hair Coarse and straight shaft, with little diameter variation. Dense unevenly distributed pigment. Presence of a continuous medulla. Round cross-section
Negroid (African American) Hair Curly,kinky. Dense unevenly distributed pigments. Variations in the diameter of the shaft. Fragmented or absent medullae. Flattened cross-section
Race Hairs
Somatic Origin The location on the body of hair found at a crime scene can be determined by noting key characteristics Types of Hair Scalp Hairs Little diameter variation More uniform distribution of pigment color Pubic Hairs Short and curly Wide variations in shaft diameter Beard Hairs Coarse, triangular cross section Blunt tips
Somatic Origin Scalp: Head hair, 100-1000mm long, 25-125 um diameter; 0.4 mm/day growth; small root; tapered tip; little diameter variation; various medullation; often with cut tips may be artificially treated Pubic: Pudendal; 10-60 mm long; coarse diameter and prominent diameter variation and buckling; broad medulla; follicular tags common; asymmetrical cross section twisted and may be straight, curved, or spirally tufted Vulvar: Secondary pubic hair; finer and shorter; may be abraded Chest: Pectoral; moderate to considerable diameter variation; long fine archlike tip; usually longer than pubic hair Beard: Facial hair; very coarse; 50-300 mm long; large root, irregular structure; often triangular cross section; complex medullation; blunted or razor cut tip; grows 0.4 mm/day Axillary: Arm pit; 10-50 mm long; grows 0.3 mm/day; coarse; blunt tip, abraded or frayed; usually straighter than pubic hair; many cortical fusi; sometimes yellowed and bleached Eyebrow: 1 cm long; 0.16 mm/day growth; curved; relatively coarse for length; smooth curve with punctuate tip and large medulla Eyelash:Ciliary; less than 1 cm long; short curved pointed hair Limb: Leg and arm hair; 3-6 mm long; fine tip; irregularly medullated; often indistinctly and slightly pigmented Ear: Tragi; pinnae; downy Buttocks: Anal hair; short blunted and abraded hair Nose: Similar to facial hair (beard)
Pubic Hair Limb Hair What s different about this hair? Beard Hair Burned hair
Association of Human Hair Characteristics used for hair comparison Scale structure Medullary index Medullary shape Color Length Diameter of hair Pigment granules shape, size and distribution Acquired Characteristics
Structure of Hair
Color of Hair
Cuticular Traits
Acquired Characteristics
Scissor Cut Razor Cut Split End Broken/Clippers
Microscopy 3 types of microscope used: Stereoscopic Microscope - gross observations of the hairs Study trace evidence on the hair s surface, spatial configuration, roots, and tips Compound or Polarizing Microscope - allows for higher magnification and resolution Delineates hair s finer structural characteristics (pigment, scale, structure, cortical fusi, medulla) Transmitted Light Comparison Microscope - compare known and unknown hairs side-by-side Mounting choices Dry mount Temporary liquid mounting media Permanent mounting media
Conclusions from Comparisons One of 3 conclusions can be reached: The hairs matched in microscopic characteristics indicating an association The hairs were not alike and therefore did not originate from the same individual No conclusion can be drawn from the evidence Factors affecting degree of certainty associated with conclusion: Number of unknown hairs found to be similar to reference hairs Number of microscopic features observed The presence of unusual characteristics Condition of specimens Completeness of reference sample collection
Was Hair Forcefully Removed? Look for follicular tag Tissue from the follicle attached to the root of the hair If a hair pulled from the body was securely attached to the follicle (anagen stage) a follicular tag will be present If there: Yes hair was pulled out If absent: Could have fallen out naturally Could have been pulled out but cannot tell because If the hair was in the telogen phase, no tissue would be attached Some individuals lack follicular tissue on plucked anagen hairs
Naturally shed hairs dislodged through combing display undamaged, clubshaped roots A hair forcibly removed from the scalp will exhibit stretching and damage to the root area Forcibly removed hairs may have tissue attached called the follicular tag
Is Hair from a Dead Body? Look for postmortem banding A dark band around the hair near the root where the skin surface meets the hair shaft Found on hairs pulled from decomposing skin If present: May indicate that the body was moved after death
Testing for Substances in the Hair Shaft 1. Chemicals that the skin absorbs often can be detected by analysis of the hair shaft. 2. A forensic scientist can perform chemical tests for the presence of various substances. 3. The hair shaft can be examined in sections to establish a timeline for exposure to toxins. 4. Neutron Activation Analysis (NAA) can determine concentrations of substances in the sample. 67
Testing the Hair Follicle Microscopic assessment of the follicle is performed first because it is cost effective and quick. If a microscopic match is found, the follicle can be blood tested and perhaps show the blood type. If a microscopic match is found, the follicle can be DNA analyzed to provide identification with a high degree of confidence. 68
Individualization of Human Hair DNA allows for the individualization of hair Nuclear DNA Found in the follicular tag Will identify hair with one individual Mitochondrial DNA Found throughout cells of hair Will identify hair to individuals of the same maternal line
Quick Review 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 crime. From hair one might be able to determine: If the source is human or animal Race (sometimes) Origin of the location on the source s body Whether the hair was forcibly removed If the hair has been treated with chemicals If certain drugs have been used
Hair consists of a (a) hair shaft produced by a (b) follicle embedded in the skin. The shaft consists of an outer cuticle, a cortex, and an inner medulla. Various hair treatments produce characteristic effects useful to forensic experts. Some characteristics allow them to be grouped into general racial categories. Forensic experts examine hair using chemicals, light, electrons, neutrons, and DNA sequencing. 71
Review of Hair Analysis Identification Comparison DNA Collect Reference Samples
References James, Stuart. Forensic Science. 2. Boca Raton, FL: CRC Press, 2005. Bell, Suzanne. Forensic Chemistry. 1. Upper Saddle River, NJ: Pearson Prentice Hall, 2006. Girard, James E.. Criminalistics: Forensic Science and Crime. 1. Sudbury, MA: Jones and Barlett Publishers Inc., 2008. Saferstein, Richard. Criminalistics: An Introduction to Forensic Science. 9. Upper Saddle River, NJ: Pearson Prentice Hall, 2007. Deedrick, Douglas. "Hairs, Fibers, Crime and Evidence." Forensic Science Communications 2.3July 2000 16 003 2008 <http://www.fbi.gov/hq/lab/fsc/ backissu/july2000/deedric1.htm>. Kathy, Steck-Flynn. "Trace Evidence: Hair." Crime and Clues: The Art and Science of Criminal Investigation. 03 009 2006. 16 Mar 2008 <http:// www.crimeandclues.com/hair_evidence.htm>. Bisbing, Richard E., (2001) Finding Trace Evidence. in Mute Witnesses: Trace Evidence Analysis. Houck, Max., (ed.) Academic Press, San Diego, California www.coolphysics.org/hair,%20fiber,%20and%20paints%2005.ppt Hamrick, Barbara. "Uranium in Hair Analysis: Responding to Public Concerns." 25 004 2004. Environmental Nuclear Council. 16 Mar 2008 <http://www.crcpd.org/ AnnualMeeting-04/05-25-04_0810-Hamrick.pdf>.