hairs and fibers. morphology and structure of hair

Hairs and FibersHairs and Fibers

Morphology and Structure Morphology and Structure of Hairof Hair

Morphology (Structure) of Morphology (Structure) of HairHair

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 hair known as the hair follicle.follicle.

Extends from its Extends from its root or bulb root or bulb embedded in the embedded in the follicle, continues follicle, continues into a shaft, and into a shaft, and terminates at a tip terminates at a tip end.end.

The Shaft of HairThe Shaft of Hair

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

Morphology: Morphology: CuticleCuticle 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 Preserving scale patternscale pattern Since examination of Since examination of

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

Differences between Differences between animal hairs & animal hairs & human hairshuman hairs There are three basic scale structures There are three basic scale structures

that make up the cuticle:that make up the cuticle:

1.1. coronal (crown-like)coronal (crown-like)

2.2. spinous (petal-like)spinous (petal-like)

3.3. 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

Differences between Differences between animal hairs & human animal hairs & human

hairshairs 1. Coronal, or crown-like scale 1. Coronal, or crown-like scale

pattern:pattern: hairs of very fine diameterhairs of very fine diameter resemble a stack of paper cupsresemble a stack of paper cups commonly found in the hairs of small commonly found in the hairs of small

rodents and bats, but rarely in human rodents and bats, but rarely in human hairshairs


Differences : animal Differences : animal hairs & human hairshairs & human hairs2. Spinous or petal-like scales:2. Spinous or petal-like scales:

triangular in shape and protrude from triangular in shape and protrude from the hair shaftthe hair shaftare found at the proximal region of are found at the proximal region of mink hairs and on the fur hairs of mink hairs and on the fur hairs of seals, cats, and some other animalsseals, cats, and some other animalsnever found in human hairs never found in human hairs


Differences between animal Differences between animal hairs & human hairshairs & human hairs3. Imbricate or flattened scales:3. Imbricate or flattened scales:

consist of overlapping scales with consist of overlapping scales with narrow marginsnarrow marginscommonly found in human hairs and commonly found in human hairs and many animal hairsmany animal hairs

Differences between animal Differences between animal hairs and human hairshairs and human hairs

Human hairs are generally Human hairs are generally consistent in color; consistent in color; whereas animal hairs may whereas animal hairs may exhibit radical color exhibit radical color changes in a short changes in a short distance, called distance, called bandingbanding. .

The pigmentation of human The pigmentation of human hairs is evenly distributed, hairs is evenly distributed, or slightly more dense or slightly more dense toward the cuticle; whereas toward the cuticle; whereas the pigmentation of animal the pigmentation of animal hairs is more centrally hairs is more centrally distributed, although more distributed, although more dense toward the medulladense toward the medulla. .

Morphology: CortexMorphology: Cortex Made of spindle-shaped Made of spindle-shaped

cells aligned in a cells aligned in a regular array, parallel to regular array, parallel to the length of the hairthe length of the hair

Embedded with Embedded with pigment granules that pigment granules that give hair its colorgive hair its color

The color, shape and The color, shape and distribution of the distribution of the granules provide points granules provide points for forensic comparisonfor forensic comparison

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

Your natural Hair color is Your natural Hair color is determined by three determined by three

factorsfactors

1. The type of natural color pigment 1. The type of natural color pigment melanin present in your hair's melanin present in your hair's cortex. cortex. Eumelanin (black pigment) Eumelanin (black pigment) Phenomelanin (red/yellow Phenomelanin (red/yellow

pigment) pigment) 2. Number of melanin granules 2. Number of melanin granules 3. Spacing of those granules (close 3. Spacing of those granules (close

together or far apart)together or far apart)

How Melanin pigments How Melanin pigments determine your natural hair determine your natural hair

color: color: Black hair: densely packed melanin granules, full of Black hair: densely packed melanin granules, full of eumelanineumelanin

Brown hair: loose pattern of eumelanin-filled Brown hair: loose pattern of eumelanin-filled

granules or granules blended with eumelanin and granules or granules blended with eumelanin and phenomelanin phenomelanin

Blonde hair: few granules with minimal bits of Blonde hair: few granules with minimal bits of eumelanin… In fact, the eumelanin is so sparse eumelanin… In fact, the eumelanin is so sparse that the color of blonde hair is the color of the hair that the color of blonde hair is the color of the hair fiber itself. fiber itself.

Red hair: loosely packed granules containing Red hair: loosely packed granules containing phenomelaninphenomelanin

What causes gray hair?What causes gray hair? As you age, your natural production of As you age, your natural production of

pigment slows down and your natural pigment slows down and your natural color loses its color strength. color loses its color strength.

This doesn't happen to every hair at the This doesn't happen to every hair at the same time, so the contrast between the same time, so the contrast between the hair with no color and the hair that still hair with no color and the hair that still has some color causes it to look gray. has some color causes it to look gray.

So how gray your hair actually looks is So how gray your hair actually looks is determined by the percentage of determined by the percentage of strands with no color vs. the pigmented strands with no color vs. the pigmented strands. strands.

Morphology: Morphology: MedullaMedulla

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

Medullary Medullary IndexIndex

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)20

Medulla of Different Medulla of Different SpeciesSpecies

Forensic Forensic Analysis of 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 ones; except or may be fragmented ones; except Mongoloid (Asian) race whose medulla is Mongoloid (Asian) race whose medulla is usually continuoususually continuous

Most animals have medulla that is continuous Most animals have medulla that is continuous or interruptedor interrupted

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: string of pearlsCats: string of pearls Deer: spherical occupying whole hair shaftDeer: spherical occupying whole hair shaft

Comparison of Animal and Comparison of Animal and Human HairHuman Hair

Medullary Index ≥1/2

Medulla is present for Medulla is present for all animalsall animals

Medulla is continuous Medulla is continuous for most animalsfor most animals

Medulla is patterned for Medulla is patterned for most animalsmost animals

The pattern can tell The pattern can tell the species!the species!

Medullary Index <1/3

Medulla is absent for Medulla is absent for most humansmost humans

Medulla is Medulla is continuous for continuous for Mongoloid raceMongoloid race

Medulla is fragmented – only some animals and humans

Medulla is cylindrical in shape (most animals)

Identification and Identification and Comparison of HairComparison of Hair

Morphological Characteristics do Morphological Characteristics do not allow individualization not allow individualization of a of a human hair to any single head or human hair to any single head or bodybody

Hair when collected with an Hair when collected with an adequate number of adequate number of standards/references can provide standards/references can provide strongstrong circumstantial evidencecircumstantial evidence

Scale structure, medullary index, Scale structure, medullary index, and medullary shapeand medullary shape are most are most often used for hair comparisonoften used for hair comparison

Human HairsHuman Hairs(Testify)(Testify)

Racial DeterminationRacial Determination Body AreaBody Area Age and Sex?Age and Sex? Forcibly Removed?Forcibly Removed?

Can the racial origin Can the racial origin of hair be of hair be

determined?determined? Forensic terms: Forensic terms: Caucasoid, African/West Caucasoid, African/West India, MongoloidIndia, Mongoloid

Mongoloid has Mongoloid has continuous medullaecontinuous medullae

Caucasian has even Caucasian has even distribution of pigment distribution of pigment in cortexin cortex

African/West India has African/West India has unevenly distributed unevenly distributed pigment.pigment.

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

Racial DeterminationRacial Determination

African

Mongoloid

Caucasoid

Usually kinky, containing dense, unevenly distributed pigments.

Cross section is flat to oval in shape.

Usually straight or wavy with very fine to coarse pigments that are more evenly distributed .

Cross section are oval to round in shape.

Usually coarse containing pigment granules larger in size than Caucasians.

Cross sections are round in shape.

Cross section

varieties.

Head Hairs

Long with moderate shaft diameter and diameter variation Long with moderate shaft diameter and diameter variation

Medulla absent to continuous and relatively narrow when Medulla absent to continuous and relatively narrow when compared to the structure of hairs from other body areas compared to the structure of hairs from other body areas

Often with cut or split tips Often with cut or split tips

Can show artificial treatment, solar bleaching, or Can show artificial treatment, solar bleaching, or mechanical damage mechanical damage

Soft texture, pliable Soft texture, pliable

Pubic Hairs

Medulla relatively broad and usually continuous when present

Root frequently with tag

Tip usually tapered, rounded, or abraded

Stiff texture, wiry

Shaft diameter coarse with wide variations and buckling

Limb HairsLimb Hairs

Tips usually Tips usually tapered, often tapered, often blunt and blunt and abraded, abraded, rounded scale rounded scale ends due to ends due to wearwear

Diameter fine with little Diameter fine with little variation variation

Gross appearance of hair Gross appearance of hair is arc-like in shape is arc-like in shape

Medulla is Medulla is discontinuous to discontinuous to trace with a trace with a granular granular appearanceappearance

Soft textureSoft texture

Facial Hairs (Beard/Mustache)

Diameter very coarse with Diameter very coarse with irregular or triangular cross-irregular or triangular cross-sectional shape sectional shape

Medulla very broad and Medulla very broad and continuous, may be doubledcontinuous, may be doubled

Chest Hairs

Shaft diameter moderate and variable Shaft diameter moderate and variable

Tip often darker in color, long and fine, Tip often darker in color, long and fine, arc-like arc-like

Medulla may be granular Medulla may be granular

Stiff texture Stiff texture

Axillary or Underarm Axillary or Underarm HairsHairs

Resemble pubic hairs in general Resemble pubic hairs in general appearance, but less wiry appearance, but less wiry

Medullary appearance similar to limb hairs Medullary appearance similar to limb hairs

Diameter moderate and variable with less Diameter moderate and variable with less buckling than pubic hairs buckling than pubic hairs

Tips long and fine, frequently with bleached Tips long and fine, frequently with bleached appearanceappearance

Other Body Hairs

Eyebrow: Eyebrow: Stubby, some Stubby, some diameter fluctuation, saber-like in diameter fluctuation, saber-like in appearance appearance

Eyelash: Eyelash: Short, stubby with little Short, stubby with little shaft diameter fluctuation, saber-shaft diameter fluctuation, saber-like in appearance like in appearance

Trunk: Trunk: A combination of features of limb A combination of features of limb and pubic hairs, a transitional hair and pubic hairs, a transitional hair

Tip of the ShaftTip of the Shaft

Burned Cut Razored Split

Root of HairRoot of Hair Provide the tools to produce hair and Provide the tools to produce hair and

continue its growthcontinue its growth 3 Stages of Growth 3 Stages of Growth (different looking roots)(different looking roots)

AnagenAnagen -initial phase may last up to 6 years, -initial phase may last up to 6 years, root is flame shapedroot is flame shaped

CatagenCatagen –transition phase (2-3 weeks), root is –transition phase (2-3 weeks), root is elongatedelongated

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

Hair Growth CycleHair Growth Cycle

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.

Collection of Hair Collection of Hair EvidenceEvidence


Questioned and Reference hair must Questioned and Reference hair must come from same area of the body; come from same area of the body; one cannot, for instance compare one cannot, for instance compare head hair to pubic hair.head hair to pubic hair.

The collection of 50 full length hairs The collection of 50 full length hairs from all areas of the scalp will from all areas of the scalp will normally ensure a representative normally ensure a representative sampling of head hair.sampling of head hair.


A minimum collection of 24 full length A minimum collection of 24 full length pubic hairs should cover the range of pubic hairs should cover the range of characteristics present in this type of characteristics present in this type of hair.hair.

All collected hairs must be full-length All collected hairs must be full-length so that the investigator can see if the so that the investigator can see if the color and morphological features vary color and morphological features vary throughout the length of the hair.throughout the length of the hair.

What does this mean…..?What does this mean…..? To victims of a Sexual To victims of a Sexual

Assault?Assault?

Do you think this would Do you think this would increase or decrease the increase or decrease the likelihood that a person likelihood that a person would file charges against would file charges against their attacker?their attacker?

Packaging of Hair Packaging of Hair EvidenceEvidence

Recover all hair present. If possible, use fingers or tweezers to pick up hair, place in paper bindles or coin envelopes which should then be folded and sealed in larger envelopes.

Label the outer sealed envelope.

If hair is attached, such as in dry blood, or caught in metal or a crack of glass, do not attempt to remove it but rather leave hair intact on the object.

If the object is small, mark it, wrap it, and seal it in an envelope.

If the object is large, wrap the area containing the hair in paper to prevent loss of hairs during shipment

Fibers…. Fibers….

Fall into two main categories….Fall into two main categories…. 1. Natural1. Natural non- synthetic non- synthetic 2. Man- Made 2. Man- Made synthetic synthetic

Fibers: Natural---Non-Fibers: Natural---Non-syntheticsynthetic

Derived entirely from animal or Derived entirely from animal or plant sourcesplant sources

Most prevalent plant fiber is Most prevalent plant fiber is cotton. cotton.

Its widespread use has made its 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 intervals with twists at regular intervals

Animal sources include sheep Animal sources include sheep (wool), goats (mohair, (wool), goats (mohair, cashmere) and many other cashmere) and many other sourcessources

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

Wool

Cotton

Linen - stem fiber from flax plant

Kapok - from seed hairs of kapok plant

Other fibers - Manila, hemp, sisal, jute

Other Plant FibersOther Plant Fibers::

Trace > Fibers > Natural

CottonLinen Hemp

sisal

jute

Mineral FibersMineral Fibers

Asbestos - crystalline material Used to be used for insulation Fractures into thin rods that

can get into your lungs; can kill you

Not used much anymore

Trace > Fibers > Natural

Filament: Long continuous fiber (like silk)

Staple: Filament is cut into smaller pieces; staples are spun together to form thread (like cotton)

Trace > Fibers

Filament vs. StapleFilament vs. Staple

Man-Made Fibers: aka Man-Made Fibers: aka “Synthetic”“Synthetic”

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

Class characteristicsClass characteristics

Trace > Fibers > Analysis

Color: microscopic examination

Size: length and width can be measured

Shape: cross section is viewed

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

ID and Comparison of ID and Comparison of Man-Made Fibers con’t.Man-Made Fibers con’t.

The chemical makeup of the fiber itself can be The chemical makeup of the fiber itself can be examined through the following:examined through the following:

Infrared microspectrophotometryInfrared microspectrophotometry Refractive IndexRefractive Index

The chemical makeup of the dyes in the fiber The chemical makeup of the dyes in the fiber can be examined through the following:can be examined through the following:

Liquid chromatographyLiquid chromatography Visible light microspectrophotometryVisible light microspectrophotometry

Chemical Composition: determined by Chemical Composition: determined by advanced instrumentationadvanced instrumentation

Trace > Fibers > Analysis

Class characteristics

PaintForensicsPaintForensics

What is paint?What is paint? What crimes are paint involved in?What crimes are paint involved in? How is paint collected?How is paint collected? How is paint analyzed in the lab?How is paint analyzed in the lab?

What is paint?What is paint?

Colored chemical coating Covers cars and houses

Trace > Paint

Paint contains 3 types of substances: Vehicle – binds components together,

adjusts the viscosity ( how well it flows) Pigment – gives paint color Extenders – used to modify gloss, texture,

opacity, etc.

What is paint?What is paint?Trace > Paint

Automotive PaintAutomotive Paint

Electrocoat primer Electrocoat primer – the first layer – the first layer applied to the steel body of the car.applied to the steel body of the car.

* The primer consists of epoxy based * The primer consists of epoxy based resins which is electroplated onto resins which is electroplated onto

the the steel body of the automobile to steel body of the automobile to provide provide corrosion resistance.corrosion resistance.

* The color of these electrodeposition * The color of these electrodeposition primers ranges from black to gray.primers ranges from black to gray.

Automotive PaintAutomotive Paint Primer surfacer Primer surfacer – layer of coating that – layer of coating that

usually follows the electrocoat layer and is usually follows the electrocoat layer and is applied before the base coat.applied before the base coat.

*Primer surfacers are epoxy modified *Primer surfacers are epoxy modified polyesters polyesters or urethanes.or urethanes.

** This layer is highly pigmented. Color ** This layer is highly pigmented. Color pigments are used so as to minimize color pigments are used so as to minimize color

contrast between primer and topcoats.contrast between primer and topcoats.

Automotive PaintAutomotive Paint Basecoat Basecoat – layer that provides the color and – layer that provides the color and

aesthetics of the finish and therefore represents aesthetics of the finish and therefore represents the “eye appeal” of the finished automobile.the “eye appeal” of the finished automobile.

**The integrity of this layer is dependent on its **The integrity of this layer is dependent on its ability to resist the elements of weather, ability to resist the elements of weather,

UV UV radiation and acid rain.radiation and acid rain.

There is also a growing trend toward pearl There is also a growing trend toward pearl luster or mica pigments.luster or mica pigments.

Automotive Paint:Making Automotive Paint:Making PaintPaint

Mica pigments Mica pigments are coated with layers are coated with layers of metal oxide to generate of metal oxide to generate interference colors.interference colors.

The addition of The addition of aluminum flakes aluminum flakes to to automotive paint will impart a automotive paint will impart a metallic look to the paint’s finish.metallic look to the paint’s finish.

Automotive PaintAutomotive Paint ClearcoatClearcoat – An unpigmented – An unpigmented

clearcoat is clearcoat is applied to improve gloss, applied to improve gloss, durability and durability and appearance. appearance.

* Most clearcoats are acrylic * Most clearcoats are acrylic based, but polyurethane based, but polyurethane clearcoats are increasing inclearcoats are increasing inpopularity.popularity. * The clearcoat provides an * The clearcoat provides an outstanding etch resistance andoutstanding etch resistance andappearance.appearance.

What crimes are paint involved in?What crimes are paint involved in?

Hit and Runs – paint from car left at scene Other vehicular accidents Home invasion – windows; on suspect

Trace > Paint

How is paint collected? How is paint collected?

Visually by hand or with forceps. Packaged in sealed containers.

Trace > Paint

How is paint analyzed?How is paint analyzed?

1. Possibly a physical match (jigsaw-like)

2. Associate the unknown paint with a known sample (class characteristics)

Trace > Paint

Chemical composition determined by FT-IRFTIR (Fourier Transform Infrared) Spectroscopy, or simply FTIR Analysis, is a failure analysis technique

that provides information about the chemical bonding or molecular structure of materials,

whether organic or inorganic.

Trace > Paint > Analysis

How is paint analyzed?How is paint analyzed?

Chemical “Fingerprint”

Paint can be in multiple layersPaint can be in multiple layers

Each layer is analyzed to determine its physical and chemical properties.

Trace > Paint > Analysis

hairs and fibers. morphology and structure of hair

Documents