Hair and Fiber The study of important trace

Hair and Fiber The study of important trace evidence www. coolphysics. org/Hair, %20 Fiber, %20 and%20 Paints%2005. ppt

Important Forensic Questions n n n Can the body area from which a hair originated be determined? Can the racial origin of hair be determined? Can the age and sex of an individual be determined from a hair sample? Is it possible to determine if a hair was forcibly removed from the body? Are efforts being made to individualize human hair? Can DNA individualize a human hair?

Morphology and Structure of Hair

Hair Morphology Con’t

Morphology: Cuticle n n Protective coating made of overlapping scales, produce a characteristic pattern Scales always point toward tip of hair Not useful in individualizing human hair Can be used for species identification

Cuticle Types Mosaic Imbricate Pectinate Petal Diamond

Morphology: Cortex n n n Made of spindle-shaped cells aligned in a regular array, parallel to the length of the hair Embedded with pigment granules that give hair its color The color, shape and distribution of the granules provide points forensic comparison

Morphology: Medulla n canal like structure of cells that runs through the center of the cortex

Medullary Index n n Measure of the diameter of the medulla relative to the diameter of the hair shaft Usually expressed as a fraction Humans: best if medullary index < 1/3 Animals: best if medullary index > 1/2

Medulla of Different Species

Forensic Analysis of Medulla n n n Presence of medulla varies quite a bit: even hair to hair Human head hairs generally have no medulla or may be fragmented ones; except Mongoloid race whose medulla is usually continuous Most animals have medulla that is continuous or interrupted The shape of the medulla can help identify a species Examples: n n n Most animals and humans: cylindrical Cats: pearl shape Deer: spherical occupying whole hair shaft

Identification and Comparison of Hair n n n No individualization of a human hair to any single head or body Hair when collected with an adequate number of standards/references can provide strong circumstantial evidence Scale structure, medullary index, and medullary shape are most often used for hair comparison

Morphology: Root n Human hair grows in three developmental stages: anagen, catagen, and telogen phases

Root: Anagen Phase n n Initial growth phase during which hair follicle is actively producing hair, phase may last 6 years, root is flame like in appearance When pulled this root may contain a follicular tag (rich source of DNA) Anagen hair root Root w/ follicular tag

Root: Catagen Phase n A transition phase—hair grows at a decreasing rate for two to three weeks —elongated appearance as root bulb shrinks and is being pushed out of hair follicle Catagen hair root

Root: Telogen phase n Hair growth has ended—root takes on a club-like appearance—during two-six month period, the hair will be pushed out of the follicle causing the hair to shed naturally Telogen hair root

Important Forensic Questions n n n Can the body area from which a hair originated be determined? Can the racial origin of hair be determined? Can the age and sex of an individual be determined from a hair sample? Is it possible to determine if a hair was forcibly removed from the body? Are efforts being made to individualize human hair? Can DNA individualize a human hair?

Identification and Comparison of Hair (cont) n n n Evidential value lies with degree of probability associated with a questioned hair and a particular individual 11 percent of all morphological hair matches are generally found to be non-matches; need DNA to augment findings Mitochondrial DNA can be analyzed from any part of the hair n n Often cost and time prohibitive; samples often contaminated Nuclear DNA can be analyzed if hair was pulled forcefully

What can be determined n Body areas: n n n Scalp hairs show little variation of diameter and have more uniform distribution of pigment color Pubic hair are short, curly with a wide range of variations in shaft diameter and a continuous medulla Beard hairs: coarse and usually triangular in cross-section with blunt tips from cutting or shaving

What can be determined n Racial origin: n n n Can distinguish between Negroid and Caucasian head hair Negroid hair: normally kinky, containing dense, unevenly distributed pigments Caucasian hair: straight or wavy, with very fine to coarse pigments that are more evenly distributed when compared to Negroid hair Cross sections of Caucasian hair are oval to round in shape Negroid hair are flat to oval in shape These are general in nature

What can be determined n Age cannot be determined with any degree of certainty except with infant hair n n n Fine, short in length, have fine pigment and are rudimentary in character Sexual discrimination at this time is not considered to be a routine forensic technique Microscopic examination of the hair root may establish if the hair has fallen out or has been pulled out n Hair root with follicular tissue adhering to it is indicative that the hair has been pulled out

What can be determined n Microscopic examination of the hair root may establish if the hair has fallen out or has been pulled out n n n Hair root with follicular tissue adhering to it is indicative that the hair has been pulled out Hair naturally falling out will have a bulbousshaped root free of adhering tissue It has been demonstrated that a root may be devoid of any adhering tissue even though it was pulled out from the body n Hairs pulled out quickly are more likely to have sheath cells when compared to hairs that have been pulled out slowly

What can be determined n n The current approach for examination of hair is the morphological characteristics Breakthroughs in nuclear DNA typing has extended the technology to the individualization of human hair n n Examiners can link a particular human hair to an individual by characterizing the nuclear DNA in the hair root or follicular tissue adhering to the root Higher rate of success extracting DNA from a hair in the anagen phase or anagen hairs entering the catagen phase then those in the telogen phase

What can be determined n FBI has initiated a program to compare human head hair and pubic hair through DNA analysis n Mitochondrial DNA: is found located outside the nucleus n n Only transmitted from mother to child Many copies of mitochondrial DNA in cells as compared to nuclear DNA

Collection n n Crime scene hairs must always be accompanied by an adequate amount of control samples from the victim and from suspects Hair from any one area of the body varies significantly. The questioned hairs and control hairs must come from the same area of the body

Collection n n Forensic hair comparisons usually involve scalp or pubic hairs Collection of 50 full length hairs from all areas of the scalp A minimum of two dozen full length pubic hairs In rape cases care must be taken to first comb the pubic area to remove all foreign hair present before the victim is sampled for control hair

Collection n The entire length must be collected because the variation of color and other morphological features extend over the entire length n n n Accomplished by pulling the hair out of the skin Clipping the hair at the skin line As a matter of routine hair samples are collected from the victim(s) of a suspicious death during an autopsy

Fibers: Natural n n n Derived entirely from animal or plant sources Most prevalent plant fiber is cotton. Its widespread use has made its evidential value almost meaningless Cotton has a ribbon-like shape with twists at regular intervals (see pg 207 text) Animal sources include sheep (wool), goats (mohair, cashmere) and many other sources

Man-Made Fibers n n n Fibers derived from either natural or synthetic polymers The fibers are made by forcing polymeric material through the holes of a spinneret Rayon and then nylon were the first two man-made fibers (year 1911)

Man-Made Fibers Con’t n Regenerated Fibers n n n Made from regenerated cellulose (wood or cotton pulp) Include such fibers as rayon, acetate, and triacetate Synthetic Fibers n n n Currently manufactured Made from synthetic chemicals called polymers Include such fibers as nylons, polyesters, and acrylics

Polymers n n Basic chemical substance of all synthetic fibers Consist of long chains of repeating molecules. The repeating molecular units in the polymer are called monomers. (see pic p 210) Often referred as macromolecules or “big” molecules Countless varieties exist

Hairs, Fibers, Crime, and Evidence Part 2: Fiber Evidence Douglas W. Deedrick Unit Chief Trace Evidence Unit Federal Bureau of Investigation Washington, DC

Flax Fibers Wool Fibers Flax fibers viewed with polarized light Wool fibers

Cross section of man-made fibers Cross-sectional views of nylon carpet fibers as seen with a scanning electron microscope (SEM)

Polarized Light Orlon Rayon Acetate Nylon

ID and Comparison of Man. Made Fibers n n n Fabrics that can be fitted together at their torn edge are easy to match Microscopic comparison of color and diameter Comparison of lengthwise striations and pitting on the surface of a fiber The shape of the fiber—ex. Wayne Williams case Note: Combined factors of color, size, shape, microscopic appearance, chemical composition, and dye content make it very unlikely to find two different people wearing identical fabrics

Tools and Techniques to Aid in Comparing Fibers n n Light infrared spectrophotometer—compares colors and chemical composition through spectral patterns Chromatography—compares dye composition Refraction—ID’s fiber by refractive index Comparison microscope—reveals shape, coloring, pitting and striations

Techniques n n n SEM Cast of its surface Casts were made of the hairs using clear nail polish, in order to provide optimum study preparation; the contrast and definition are both greatly improved

Identification and Comparison Establish if the hair is human or animal õ Compare if the hair retrieved at the crime scene is compatible from a known hair of a particular individual õ The ability to distinguish human from animal is easy when compared to that of human hair comparison õ õ Various morphological characteristics between individuals and the same individual

Identification and Comparison õ Microscopic examination Animal or human õ Species of animal õ õ Important characteristics: Scale structure õ Medullary index õ Medullary shape õ

Identification and Comparison Scalp hair õ Pubic hair õ Comparison microscope õ Hair from any part of the body exhibits a wide range of characteristics the examiner must have an adequate number of known hair samples that are representative of all its features õ

Identification and Comparison õ Compare Length õ Color õ Diameter õ Presence or absence of medulla õ Distribution, shape and color intensity of the pigment granules present in the cortex õ Dyed, bleached or natural hair õ

Identification and Comparison õ õ Dyed hair: dye color found in cuticle as well as throughout cortex Bleaching: removes pigment from the hair and gives a yellowish tint If there has been growth of hair since last bleach or dye treatment: natural-end will be distinct in color Hair is known to grow at an approximate rate of 1 cm/month õ Therefore can estimate the time since last appointment or treatment

Identification and Comparison õ Morphological abnormalities; õ õ õ Diseases Deficiencies Fungal and nit infections Class evidence If one human head hair taken from the crime scene is found to be similar to a representative hair from a suspect’s head, the odds against it from originating from another person are about 4500 to 1 The odds of two different pubic hairs originating from two different individuals is 800 to 1

Identification and Comparison õ Mongoloid and Negroid hairs exhibit less variations in many characteristics

Hair Morphology

Hair Morphology

Hair Morphology n n n Not possible to individualize a human hair to any single head or body Color and structure (morphology) is the most characteristic forensic features The shaft is composed of three layers n n n Cuticle Cortex Medulla

Cuticle n Hair is a good subject for establishing individual identity do to: n n n Resistance to chemical decomposition Retain its structural features over a long period of time This resistance and stability is contributed to the cuticle

Cuticle n n n Formed by overlapping scales that always point to the tip of each hair Scales formed from specialized cells that have keratinized and flattened in progressing from the follicle Shingles of a roof n Variety of patterns useful for species identification

Animal Cuticle human head hair cat dog mouse

Cortex n Made up of spindleshaped cortical cells n n n Aligned in a regular array Parallel to the length of the hair Imbedded with pigment granules n Granules provide points of comparison between different individuals

Hair Taxonomy

Medulla n n n Collection of cells that have the appearance of a central canal Usually most predominant feature Medullary index: n n Measures diameter of medulla relative to diameter of the hair shaft Expressed as a fraction Humans 1/3 Most other animals 1/2

Medulla n n n Medulla vary between individuals Vary between hairs of the same individual Some hairs have no medulla

Medulla n Classified as: n n n Interrupted Fragmented Absent Continuous Human head hairs n n n No medulla Fragment Mongoloid race shows continuous

Medulla n Animals n n Continuous Interrupted

Arrangements 1. Uniserial--small blocks in a row 3. Vacuolated--uneven pattern 4. Lattice--circular patterns 2. Multiserial--several rows of blocks across 5. Amorphous--without a specific pattern

Animals MUSKRAT RABBIT--uniserial RABBIT--multiserial COW

Human Hair

Human Hair B Very fair IV Red N Light Brown U Brown-Black

Human Hair—Some Effects A razor-cut hair A hair with a cut tip A hair showing buckling A split hair

Root n Root and surrounding cells in the hair follicle provide for: n n Production of hair Continued growth Human hair grows in three phases The shape and size of the hair root is dependent on the phase of development

Phases 1) Anagen - Growth Phase n 2) Catagen - Transitional phase n 3) Telogen - Resting Phase n

Anagen Phase q Approximately 85% of all hairs are in the growing phase at any one time. The anagen phase or growth phase can vary from two to six years. Hair grows approximately 10 cm per year and any individual hair is unlikely to grow more than one meter long

Anagen Phase q q Flame-shaped appearance of the root bulb When pulled from the root q q q Contain a follicular tag Individualization of hair DNA

Catagen Phase q q At the end of the anagen phase the hairs enters into a catagen phase which lasts about two or three weeks During the catagen phase the hair follicle shrinks to about 1/6 of the normal length. The lower part is destroyed and the dermal papilla breaks away to rest below

Catagen Phase q q q Roots typically take on an elongated appearance Root bulb shrinks in size Being pushed out of the follicle

Telogen Phase n The resting phase follows the catagen phase and normally lasts about 2 -6 -months. During this time the hair does not grow but stays attached to the follicle while the dermal papilla stays in a resting phase below. Approximately 10 -15 percent of all hairs are in this phase at an one time.

Telogen Phase n At the end of the telogen phase the hair follicle re-enters the Anagen phase. The dermal papilla and the base of the follicle join together again and a new hair begins to form. If the old hair has not already been shed the new hair pushes the old one out and the growth cycle starts all over again

What can be determined n Body areas: n n n Scalp hairs show little variation of diameter and have more uniform distribution of pigment color Pubic hair are short, curly with a wide range of variations in shaft diameter and a continuous medulla Beard hairs: coarse and usually triangular in cross-section with blunt tips from cutting or shaving

What can be determined n Racial origin: n n n Can distinguish between Negroid and Caucasian head hair Negroid hair: normally kinky, containing dense, unevenly distributed pigments Caucasian hair: straight or wavy, with very fine to coarse pigments that are more evenly distributed when compared to Negroid hair Cross sections of Caucasian hair are oval to round in shape Negroid hair are flat to oval in shape These are general in nature

What can be determined n Age cannot be determined with any degree of certainty except with infant hair n n n Fine, short in length, have fine pigment and are rudimentary in character Sexual discrimination at this time is not considered to be a routine forensic technique Microscopic examination of the hair root may establish if the hair has fallen out or has been pulled out n Hair root with follicular tissue adhering to it is indicative that the hair has been pulled out

What can be determined n Microscopic examination of the hair root may establish if the hair has fallen out or has been pulled out n n n Hair root with follicular tissue adhering to it is indicative that the hair has been pulled out Hair naturally falling out will have a bulbousshaped root free of adhering tissue It has been demonstrated that a root may be devoid of any adhering tissue even though it was pulled out from the body n Hairs pulled out quickly are more likely to have sheath cells when compared to hairs that have been pulled out slowly

What can be determined n n The current approach for examination of hair is the morphological characteristics Breakthroughs in nuclear DNA typing has extended the technology to the individualization of human hair n n Examiners can link a particular human hair to an individual by characterizing the nuclear DNA in the hair root or follicular tissue adhering to the root Higher rate of success extracting DNA from a hair in the anagen phase or anagen hairs entering the catagen phase then those in the telogen phase

What can be determined n FBI has initiated a program to compare human head hair and pubic hair through DNA analysis n Mitochondrial DNA: is found located outside the nucleus n n Only transmitted from mother to child Many copies of mitochondrial DNA in cells as compared to nuclear DNA

Collection n n Crime scene hairs must always be accompanied by an adequate amount of control samples from the victim and from suspects Hair from any one area of the body varies significantly. The questioned hairs and control hairs must come from the same area of the body

Collection n n Forensic hair comparisons usually involve scalp or pubic hairs Collection of 50 full length hairs from all areas of the scalp A minimum of two dozen full length pubic hairs In rape cases care must be taken to first comb the pubic area to remove all foreign hair present before the victim is sampled for control hair

Collection n The entire length must be collected because the variation of color and other morphological features extend over the entire length n n n Accomplished by pulling the hair out of the skin Clipping the hair at the skin line As a matter of routine hair samples are collected from the victim(s) of a suspicious death during an autopsy

Types of Fibers

n Fibers comprise our fabrics and garments n Important evidence in incidents that involve personal contact n n Homicide Assault Sexual offenses The force of impact between a hit-and-run victim and vehicle n n n Fibers Threads Clothing pieces

n Breaking-and-entering n n Fibers can adhere to broken glass and screens The development of fibers, fabrics, finishes, and other textile-processing techniques has made greater advances since the 1900’s than the four-five thousand years of recorded history

Types of Fibers n Natural fibers n Animals n n n n Wool -sheep Mohair, cashmere - goats Camels Llamas Alpacas Vicunas Fur fibers- mink, rabbit, beaver, and muskrat Identification and comparison will rely solely on color and morphological features viewed with the microscope

Types of Fibers n Plant fiber n n Cotton- most prevalent Wide use of undyed cotton fibers in clothing and other fabrics: This evidence is meaningless Dyed cotton in a combination of colors: some cases used to enhance its evidential significance Microscopic distinguishing feature: ribbonlike shape with twists at irregular intervals

Man-Made Fibers n n n 1911 Rayon 1920’s Cellulose acetate 1939 Nylon Increasing replacing natural fibers Fibers are marketed under trademark names, so to avoid confusion, the U. S. Federal Trade Commission has approved “generic” or family names for the grouping of all man-made fibers

n Polyesters n U. S. n n Dacron. R, Fortrel. R, Kodel. R England n Terylene. R

n n First machine-made fibers derived from cotton or wood pulp Regenerated fibers: n n n Raw materials from cotton or wood pulp Processed Pure cellulose is extracted Type of fiber desired, the cellulose is chemically treated and dissolved in solvent Forced through the small holes of a spinning jet or spinneret Rayon, acetate, triacetate: Regenerated cellulose

n Synthetic fibers: produced solely from synthetic chemicals Nylons n Polyesters n Acrylics n n Creation of synthetic fibers came about when scientist developed the method of synthesizing long-chained molecules (polymers)

Glass rod in placed in a beaker in contact with viscous material n Slowly pull glass rod away n Substance adheres to rod n Forms a fine filament n Hardened as soon as it enters cool air n Cold filaments could be stretched several times their extended length n n n Flexible, strong, attractive fiber Nylon first synthetic approved fiber

n Polymer is the basic chemical substance of all polymers Plastics n Paints n Adhesives n Synthetic rubber n Can be made to assume different chemical and physical properties n n Chemical substances are composed of the molecule, the basic structural unit n H 2 O

n Heroin: C 21 H 23 O 5 N Polymers are formed by linking together a large number of molecules: macromolecules n Resembles a long repeating chain n Monomers are the repeating molecular units n Varying the chemical structure of the monomers and devising numerous ways of weaving them together n n Polymers that exhibit different properties

n This versatility enables the synthesis of: Glues n Plastics n Paints n Fibers n In nature these chemical principles produce hair and vegetable fibers n Cellulose, the basic ingredient of wood and cotton and Starch are both natural polymers made up of carbohydrate molecules n

Polarized Light Microscopy Digital Image Gallery http: //microscopy. fsu. edu/primer/techniques/polarized/gallery/pages/orlonsmall. html

n n If presented with fibers that can exactly be fitted together at the torn edges: common origin of fabric Usually fibers must be viewed at a side by side comparison n n Microscopic examination for color Microscopic examination for diameter Lengthwise striations on the surface Pitting of fiber’s surface with delustering particles (titanium dioxide) Shape of fiber through cross-sectional view

Fig. 2. SEM image at 10000 magnification and 20 k. V of titania coated nylon-6 nanofibers obtained through the sol gel coating technique. The average diameter of the fibers is about 150 - 200 nm.

n n n Dyed fibers can look the same but their composition may be different Visible light microspectrophotometer compares the colors of fibers through special patterns More detail: chromatographic separation These tests are performed to show the fibers belong in the same generic class Can be enhanced if it shows that the fibers belong to the same subclassification within their generic class

n Nylon 6, Nylon 6 -10, Nylon 11, and Nylon 6 -6 n n n May differ in physical shape Differ appearance Differ in dyeability Do to modifications in basic chemical structure Many manufactured fibers exhibit birefringence n n The regular arrangement of the fiber, s polymers cause crystallinity in the finished fiber The crystallinity; n n n Strength Stiff Optical property of double refraction

n Infrared spectrometry n Rapid and reliable method for identifying generic class and in some instances the subclass

Collection n n This evidence will usually not be seen by the naked eye Identify and preserve potential “carriers” of fiber evidence n n n Packaged separately in paper bags Some articles must not be placed on the same surface prior to packaging Carpets, rugs, and bedding: folded carefully to protect areas suspected of having fiber evidence Car seats: covered with polyethylene sheets Adhesive tape lifts of exposed body areas of victim

Forensic Examination of Paint n n n One of the most prevalent forms of physical evidence Perhaps most frequently encountered in hit-and-run and burglary cases Small quantities of paint recovered from an accident scene n Color, make, and model of automobile

n Paint on a surface will dry into a hard film n n Pigments n n Consists of pigments and additives suspended in a binder and dissolved in a suitable solvent Color Opacity Usually mixtures of different inorganic and organic compounds Binder n n Support medium Polymeric substance

n Automobile paint: n n Manufacturers apply any number of coatings to the automobile’s body Automobile finishing system for steel: n Electrocoat primer: epoxy-based resins n n Electroplated to prevent corrosion Uniform in appearance Colors range from gray to black Primer surface: epoxy-modified polyesters n n Function is to completely smooth out and hide seams and imperfections Highly pigmented: color pigments are used to minimize color contrast between primer and topcoats

n Automobile finishing system for steel: n n Basecoat or colorcoat: The binder is most commonly made up of an acrylic-based polymer n Provides color and aesthetics (Eye appeal) n The layers integrity is dependent on the ability to resist the elements n Use of lead , chrome, and other heavy metals has been abandoned n Organic-based pigments n Trend towards pearl luster or mica pigments (coated with a metal oxide) n Aluminum flakes imparts a metallic look Clearcoat: acrylic-based or polyurethane n Provides etch resistance n Appearance n Improves gloss and durability

n Microscope has been traditionally used for locating and comparing paint specimens n Compared side by a stereoscopic microscope for: n n Color Surface Texture Color layer sequence Paint specimens possess colored layers n When they match with respect to number and sequence of colors it can be said the two paint specimens are from the same origin

n The diverse chemical composition of today's modern paints provides for additional points of comparison n Wide variation in binder formulations n n n Significant information with respect to automobile finishes The knowledge that paint manufacturers make hundreds of finishes is most helpful when examining a paint specimen Pyrolysis gas chromatography: invaluable n Pyrogram: this pyrogram distinguishes one polymer from another in the binder

n Infrared spectrophotometry: analysis of binder composition n n Binders will actively absorb infrared radiation to yield a highly characteristic spectrum The elements that comprise the inorganic pigments can be identified by n n Emission spectroscopy Neutron activation analysis X-ray diffraction X-ray spectroscopy

n n n The emission spectrograph can simultaneously detect 15 -20 elements in most automobile paints If compared by layer structure, solvent tests, pyrolysis gas chromatography and X-ray spectroscopy the chances of a paint chip from a crime scene matching a randomly chosen vehicle is 16, 000 to 1 Starting with the 1974 model year, The Law Enforcement Standards Laboratory at the National Bureau of Standards collected and disseminated to crime labs auto paint color samples

n PDQ (Paint Data Query): database put together by the Royal Canadian Mounted Police Forensic Laboratory n n Allows for the obtaining of information on paints related to automobile make, model, and year. Parameters n n n Automotive paint layer colors Primer colors Binder composition

Collection and Preservation n n Picked up with tweezers Scooped up with a piece of paper Paper druggist folds Glass or plastic vials If paint is embedded or smeared in garments or objects, the objects or garments are packaged

Collection and Preservation n n Uncontaminated control samples must always be taken from an undamaged area as close to the damaged area as possible Removal accomplished by using a clean scalpel or knife blade to include all the paint layers n 1/4 inch square