Hairs & FibersHairs & Fibers

Purpose of HairPurpose of Hair Hair on mammals - Hair on mammals -

helps to regulate body temperature helps to regulate body temperature decrease frictiondecrease friction protect against sunlightprotect against sunlight

Location of hair on humans:Location of hair on humans: Head Head Eyebrows and eyelashesEyebrows and eyelashes Mustache and beardMustache and beard UnderarmsUnderarms Auxillary (overall body)Auxillary (overall body) PubicPubic

Morphology of HairMorphology of Hair

An appendage of An appendage of the skin that grows the skin that grows out of an organ out of an organ known as the known as the hair hair folliclefollicle..

Hair - extends Hair - extends from root or bulb from root or bulb embedded in the embedded in the folliclefollicle, continues , continues into a into a shaftshaft, and , and terminates at a terminates at a tip tip endend..

The Shaft of HairThe Shaft of Hair

Composed of Composed of three layers: three layers: cuticle, cortex, cuticle, cortex, and medulla.and medulla.

Structure of HairStructure of Hair

1. Cuticle – thin outer layer2. Cortex – thicker middle

layer3. Medulla – inner layer

Morphology: CuticleMorphology: Cuticle Protective coating made Protective coating made

of overlapping scales, of overlapping scales, produce a characteristic produce a characteristic patternpattern

Scales always point Scales always point toward tip of hairtoward tip of hair

Not useful in Not useful in individualizing human hairindividualizing human hair

Can be used for species Can be used for species identificationidentification

http://www.pg.com/science/haircare/hair_twh_35/hair_twh_35_02.jpg

Preserving scale patternPreserving scale pattern

Since examination of Since examination of internal structure of internal structure of hair requires loss of hair requires loss of scale pattern, a scale scale pattern, a scale case is made.case is made.

Clear nail polish on Clear nail polish on microscope slidemicroscope slide

Hair embedded and Hair embedded and allowed to dry before allowed to dry before removed.removed.

Cuticle - ScalesCuticle - Scales

Three basic scale structures that Three basic scale structures that make up the cuticle:make up the cuticle: coronal (crown-like)coronal (crown-like) spinous (petal-like)spinous (petal-like) imbricate (flattened) imbricate (flattened) Combinations and variations of these Combinations and variations of these

types are possible.types are possible.

http://www.fbi.gov/hq/lab/fsc/backissu/jan2004/research/2004_01_research01b.htm

Cuticle - ScalesCuticle - Scales

The coronal, or crown-like scale The coronal, or crown-like scale pattern:pattern: found in hairs of very fine diameter and found in hairs of very fine diameter and

resemble a stack of paper cups.resemble a stack of paper cups. commonly found in:commonly found in:

hairs of small rodents and bats –but-hairs of small rodents and bats –but- rarely in human hairsrarely in human hairs

http://www.fbi.gov/hq/lab/fsc/backissu/jan2004/research/2004_01_research01b.htm

Cuticle - ScalesCuticle - Scales Spinous or petal-like scales:Spinous or petal-like scales:

triangular in shape and protrude from triangular in shape and protrude from the hair shaft. the hair shaft.

Found at the proximal region of mink hairs Found at the proximal region of mink hairs and on the fur hairs of seals, cats, and some and on the fur hairs of seals, cats, and some other animals. other animals.

Never found in human hairs!!Never found in human hairs!!

http://www.fbi.gov/hq/lab/fsc/backissu/jan2004/research/2004_01_research01b.htm

Cuticle - ScalesCuticle - Scales Imbricate Imbricate or flattened scales:or flattened scales:

Consists of overlapping scales with Consists of overlapping scales with narrow margins narrow margins

commonly found in human hairs and commonly found in human hairs and many animal hairs.many animal hairs.

Morphology: CortexMorphology: Cortex

Embedded with Embedded with pigment granules pigment granules that give hair its that give hair its colorcolor

Three things for Three things for forensic comparison:forensic comparison: colorcolor shape shape distribution of the distribution of the

granulesgranules

www.pg.com/science/haircare/hair_twh_59.htm

Morphology: MedullaMorphology: Medulla

canal like structure of cells that runs canal like structure of cells that runs through the center of the cortexthrough the center of the cortex

Types of Types of MedullaMedulla

The medulla (the inner section) can be hollow The medulla (the inner section) can be hollow or filled, absent, fragmented, continuous, or filled, absent, fragmented, continuous, doubled, pigmented, or un- pigmented. doubled, pigmented, or un- pigmented.

Medullary IndexMedullary Index

Measure of the diameter of the Measure of the diameter of the medulla relative to the diameter of medulla relative to the diameter of the hair shaftthe hair shaft

Usually expressed as a fractionUsually expressed as a fraction Humans: medullary index < 1/3Humans: medullary index < 1/3 Animals: medullary index > 1/2Animals: medullary index > 1/2

Medullae Medullae of of

Different Different SpeciesSpecies

Medulla ShapeMedulla Shape Medulla shape is another characteristic Medulla shape is another characteristic

that varies from species to speciesthat varies from species to species

UNISERIAL (rabbit)

MULTISERIAL (rabbit)

VACUOLATED (dog, fox,

common)

LATTICE (deer)

AMORPHOUS (human, common)17

Medulla of Different Medulla of Different SpeciesSpecies

Forensic Analysis of Forensic Analysis of MedullaMedulla

Presence of medulla varies quite a bit: even Presence of medulla varies quite a bit: even hair to hairhair to hair

Human head hairs generally have no medulla Human head hairs generally have no medulla or may be fragmented onesor may be fragmented ones except Mongoloid (Asian) race - medulla is usually except Mongoloid (Asian) race - medulla is usually

continuouscontinuous Most animals - medulla that is continuous or Most animals - medulla that is continuous or

interruptedinterrupted The shape of the medulla can help identify a The shape of the medulla can help identify a

speciesspecies Examples:Examples:

Most animals and humans: cylindrical Most animals and humans: cylindrical Cats: pearl shape Cats: pearl shape Deer: spherical occupying whole hair shaftDeer: spherical occupying whole hair shaft

Root of HairRoot of Hair Provide the tools to produce hair and continue its growthProvide the tools to produce hair and continue its growth 3 Stages of Growth (different looking roots)3 Stages of Growth (different looking roots)

1.1. Anagen -initial phase Anagen -initial phase maymay last up to 6 years, root is last up to 6 years, root is flame shapedflame shaped

The cells around the follicle rapidly divide and deposit The cells around the follicle rapidly divide and deposit materials in the hair.materials in the hair.

2.2. Catagen –transition phase (2-3 weeks), root is Catagen –transition phase (2-3 weeks), root is elongatedelongated

3.3. Telogen –phase where hair naturally falls out of the Telogen –phase where hair naturally falls out of the skin, root is skin, root is club-shapedclub-shaped

During this stage, hairs easily can be lost.During this stage, hairs easily can be lost.

Hair Growth CycleHair Growth Cycle

Root: Anagen PhaseRoot: Anagen Phase

When pulled this root may contain a When pulled this root may contain a follicular tag (rich source of DNA)follicular tag (rich source of DNA)

Root is Root is flame shapedflame shaped

Anagen hair root

Root w/ follicular tag

Human HairsHuman Hairs

Racial DeterminationRacial Determination Age and Sex?Age and Sex? Forcibly Removed?Forcibly Removed? Can Hairs be Individualized?Can Hairs be Individualized?

Can the racial origin of hair Can the racial origin of hair be determined?be determined?

Forensic terms: Caucasoid, Forensic terms: Caucasoid, Negroid, MongoloidNegroid, Mongoloid

Mongoloid Mongoloid continuous medullaecontinuous medullae

Caucasian Caucasian even distribution of pigment even distribution of pigment

in cortexin cortex Negroid Negroid

unevenly distributed unevenly distributed pigment.pigment.

http://www.fbi.gov/hq/lab/fsc/backissu/july2000/deedric1.htm

Tip of the ShaftTip of the Shaft

Burned Cut Razored Split

Forcibly Removed?Forcibly Removed?

Pulled Forcibly Removed Shed

A normal telogen hair with a hard 'club' end, seen under (left) a light microscope and (right) an electron microscope

An anagen hair that has been plucked out: notice the soft, sticky tail

Brushed-out hairs all have this kind of root.

This is an anagen hair, one which was pulled out and not ready to be shed.

Hair IndividualizationHair Individualization

Nuclear DNA – found in nucleus of each cellNuclear DNA – found in nucleus of each cell Follicular tag – tissue adhering to root or follicleFollicular tag – tissue adhering to root or follicle Will produce odds as one in billions or one in Will produce odds as one in billions or one in

trillionstrillions Mitochondrial DNA – found outside nucleus, Mitochondrial DNA – found outside nucleus,

passed from only mother to childpassed from only mother to child Many more copies compared to nuclear DNAMany more copies compared to nuclear DNA Will not individualize, but will exclude a significant Will not individualize, but will exclude a significant

portion of populationportion of population Cannot microscopically distinguish similar hairs Cannot microscopically distinguish similar hairs

from people maternally relatedfrom people maternally related

Can DNA individualize hair?Can DNA individualize hair?

Yes! In some casesYes! In some cases Best evidence to have is matching Best evidence to have is matching

morphology AND DNAmorphology AND DNA We will talk much more in Chapter 13 We will talk much more in Chapter 13

about this!about this!

Collection of Hair EvidenceCollection of Hair Evidence

Collection of Hair EvidenceCollection of Hair Evidence Questioned and Reference hair must Questioned and Reference hair must

come from same area of the body come from same area of the body Cannot compare head hair to pubic hair.Cannot compare head hair to pubic hair.

Head hairs - 50 full length hairs from Head hairs - 50 full length hairs from all areas of the scalpall areas of the scalp

Other body parts – 25 full length hairsOther body parts – 25 full length hairs All collected reference hairs must be All collected reference hairs must be

full-length full-length

Identification and Identification and Comparison of HairComparison of Hair

Morphological Characteristics - do not Morphological Characteristics - do not individualize human hair to any single head or individualize human hair to any single head or bodybody

Hair when collected properly - provides strong Hair when collected properly - provides strong circumstantial evidencecircumstantial evidence

Most often used for comparisonMost often used for comparison Scale structureScale structure Medullary indexMedullary index Medullary shapeMedullary shape

11 percent of all morphological hair matches 11 percent of all morphological hair matches are generally found to be non-matchesare generally found to be non-matches meaning microscopic hair comparisons are meaning microscopic hair comparisons are

presumptive in nature—must be confirmed by DNA presumptive in nature—must be confirmed by DNA comparisonscomparisons

Using Hair in an Investigation Using Hair in an Investigation MacroscopicMacroscopic investigation can indicate length, color, investigation can indicate length, color,

and curliness. and curliness. MicroscopicMicroscopic investigation can indicate fine detail in hair investigation can indicate fine detail in hair

structure. structure. 1.1. Phase contrast microscopy – focuses light that passes through Phase contrast microscopy – focuses light that passes through

objects of different refractive indexesobjects of different refractive indexes shows the presence of dye or other treatments.shows the presence of dye or other treatments.

2.2. Fluorescence microscope – beam of light of a certain color is Fluorescence microscope – beam of light of a certain color is used to show particular chemicalsused to show particular chemicals

Shows fine detail in hair structureShows fine detail in hair structure3.3. Electron microscopes – directs beams of electrons at sampleElectron microscopes – directs beams of electrons at sample

provides more detail of the surface or interior of the sample. provides more detail of the surface or interior of the sample.

Testing for Substances in the Testing for Substances in the Hair Shaft Hair Shaft

Neutron Activation Analysis (NAA) Neutron Activation Analysis (NAA) : : can determine concentrations of substances can determine concentrations of substances in the sample. in the sample.

1.1. Identifies up to 14 elements in a 2 cm strand Identifies up to 14 elements in a 2 cm strand of human hairof human hair

Hair placed in nuclear reactor and bombarded Hair placed in nuclear reactor and bombarded with high energy neutronswith high energy neutrons

2.2. Probability of two individuals having same Probability of two individuals having same concentration of 9 different elements: 1 in a concentration of 9 different elements: 1 in a millionmillion

Some elements: Antimony, argon, bromine, Some elements: Antimony, argon, bromine, copper, gold, manganese, silver, sodium, zinccopper, gold, manganese, silver, sodium, zinc

Each element gives off its own gamma Each element gives off its own gamma radiation with different signalsradiation with different signals

Testing for Substances in the Hair Testing for Substances in the Hair Shaft Shaft

Chemical Analysis - Chemical Analysis - 1.1. Chemicals that the skin absorbs often can be Chemicals that the skin absorbs often can be

detected by analysis of the hair shaft.detected by analysis of the hair shaft. Arsenic, lead, drugsArsenic, lead, drugs Can be used to determine poisoning or drug Can be used to determine poisoning or drug

exposureexposure2.2. Hair shaft can establish a timeline for Hair shaft can establish a timeline for

exposure to toxins. exposure to toxins. Human hair grows ~1.3 cm per monthHuman hair grows ~1.3 cm per month If root is present, sections can be dated based on If root is present, sections can be dated based on

distance from rootdistance from root

Testing the Hair Follicle Testing the Hair Follicle

Microscopic assessment Microscopic assessment of the of the follicle is performed first because it is follicle is performed first because it is cost effective and quick. cost effective and quick. If a microscopic match is found, the If a microscopic match is found, the

follicle can be:follicle can be:1.1. blood tested blood tested and perhaps show the blood and perhaps show the blood

type. type. 2.2. DNA analyzed DNA analyzed to provide identification to provide identification

with a high degree of confidence. with a high degree of confidence.

Fibers: NaturalFibers: Natural Derived entirely from animal or Derived entirely from animal or

plant sourcesplant sources Most prevalent plant fiber:Most prevalent plant fiber:

cotton. cotton. widespread use has made its widespread use has made its

evidential value almost evidential value almost meaninglessmeaningless

Cotton has a ribbon-like shape Cotton has a ribbon-like shape with twists at regular intervalswith twists at regular intervals

Animal sources: Animal sources: sheep (wool), goats (mohair, sheep (wool), goats (mohair,

cashmere) and many other sourcescashmere) and many other sources

http://www.swicofil.com/images/cotton_microscopic.jpg http://www.e4s.org.uk/textilesonline/content/6library/report1/images/microscope_2.gif

Wool

Cotton

Man-Made FibersMan-Made Fibers

Fibers derived from either natural or Fibers derived from either natural or synthetic polymerssynthetic polymers

The fibers are made by forcing The fibers are made by forcing polymeric material through the holes polymeric material through the holes of a spinneretof a spinneret

Rayon and then nylon were the first Rayon and then nylon were the first two man-made fibers (year 1911)two man-made fibers (year 1911)

http://www.naturalvisions.co.uk/pictures/thumbnail/XMIC_0021_0001XX.jpg

Man-Made Fibers Con’tMan-Made Fibers Con’t Regenerated FibersRegenerated Fibers

Made from regenerated cellulose (wood or Made from regenerated cellulose (wood or cotton pulp) cotton pulp)

Include such fibers as rayon, acetate, and Include such fibers as rayon, acetate, and triacetatetriacetate

Synthetic Fibers Synthetic Fibers Currently manufacturedCurrently manufactured Made from synthetic chemicals called polymersMade from synthetic chemicals called polymers Include such fibers as nylons, polyesters, and Include such fibers as nylons, polyesters, and

acrylicsacrylics

PolymersPolymers

Basic chemical substance of all synthetic Basic chemical substance of all synthetic fibersfibers

Consist of long chains of repeating Consist of long chains of repeating molecules. The repeating molecular units molecules. The repeating molecular units in the polymer are called monomers. (see in the polymer are called monomers. (see pic p210) pic p210) Often referred as macromolecules or “big” Often referred as macromolecules or “big”

moleculesmolecules Countless varieties exist Countless varieties exist

ID and Comparison of ID and Comparison of Man-Made FibersMan-Made Fibers

Fabrics that can be fitted together at their torn Fabrics that can be fitted together at their torn edge are easy to matchedge are easy to match

Microscopic comparison of color and diameterMicroscopic comparison of color and diameter Comparison of lengthwise striations and pitting Comparison of lengthwise striations and pitting

on the surface of a fiberon the surface of a fiber The shape of the fiber—ex. Wayne Williams caseThe shape of the fiber—ex. Wayne Williams case

Cross sections are generally helpfulCross sections are generally helpful Note: Combined factors of color, size, shape, Note: Combined factors of color, size, shape,

microscopic appearance, chemical composition, microscopic appearance, chemical composition, and dye content make it very unlikely to find two and dye content make it very unlikely to find two different people wearing identical fabricsdifferent people wearing identical fabrics

Tools and Techniques to Aid Tools and Techniques to Aid in Comparing Fibersin Comparing Fibers

Light infrared spectrophotometer—Light infrared spectrophotometer—compares colors and chemical compares colors and chemical composition through spectral patternscomposition through spectral patterns

Chromatography—compares dye Chromatography—compares dye compositioncomposition

Refraction—ID’s fiber by refractive indexRefraction—ID’s fiber by refractive index Comparison microscope—reveals shape, Comparison microscope—reveals shape,

coloring, pitting and striationscoloring, pitting and striations