Anatomy of HairAnatomy of Hair

This is a cross section of This is a cross section of a hair showing all three a hair showing all three layerslayers

Image of a Hair Follicle Image of a Hair Follicle

Each Follicle contains a Each Follicle contains a muscle and a sweat glandmuscle and a sweat gland

Arrector Pili – the Arrector Pili – the

muscle that lifts your hairmuscle that lifts your hair

on end when you’re cold on end when you’re cold

or scaredor scared

Sebaceous gland – Sebaceous gland – produces oily secretion produces oily secretion that cleans hairthat cleans hair

Apocrine GlandApocrine Gland

Produces scent hormones called Produces scent hormones called pheromonespheromones

EpidermisEpidermis

Outer layer of skinOuter layer of skin Made up of 5 dead layers – of keratin Made up of 5 dead layers – of keratin

packed cellspacked cells

Dermis – follicle sits in Dermis – follicle sits in the dermal layerthe dermal layer

Directly beneath the epidermis. Packed Directly beneath the epidermis. Packed with nerve endings and blood vesselswith nerve endings and blood vessels

Hair Follicle – the organ Hair Follicle – the organ of hair growthof hair growth

Layers of Hair FollicleLayers of Hair Follicle

Internal and External Root Sheath – molds Internal and External Root Sheath – molds and forms growing hairand forms growing hair

Papilla – Actively dividing cells that produce Papilla – Actively dividing cells that produce hairhair

Blood Vessels – feed the growing hairBlood Vessels – feed the growing hair Bulb – Bottom of Hair Follicle – contains the Bulb – Bottom of Hair Follicle – contains the

papilla and blood vessels papilla and blood vessels Hair Shaft – Made up of Cuticle, Cortex, Hair Shaft – Made up of Cuticle, Cortex,

Medulla Medulla

Layers of the Hair FollicleLayers of the Hair Follicle

The Cuticle of Human The Cuticle of Human Hair is rough --- which is Hair is rough --- which is why we use Conditionerwhy we use Conditioner

Human, Cat, Dog, MouseHuman, Cat, Dog, Mouse

Animals have characteristic cuticle scales Animals have characteristic cuticle scales that scientists can use to determine the that scientists can use to determine the source of hair evidencesource of hair evidence

Forensic Scientists make Forensic Scientists make a glass slide prep to view a glass slide prep to view animal hair on a animal hair on a Comparison MicroscopeComparison Microscope

In some cases Forensic In some cases Forensic Scientists make a cast of Scientists make a cast of the cuticle pattern the cuticle pattern

Cellulose castCellulose cast

Medulla PatternsMedulla Patterns

BrokenBroken IntermittentIntermittent ContinuousContinuous

The Medulla of Human The Medulla of Human Hair is very thin or is not Hair is very thin or is not presentpresent

Pigment cells are found Pigment cells are found in the medulla and the in the medulla and the cortexcortex

Animal Hair vs. Human Animal Hair vs. Human HairHair

Animal Hair falls into 3 main categories, Guard Animal Hair falls into 3 main categories, Guard Hairs, Wool Hairs, Whisker hairsHairs, Wool Hairs, Whisker hairs

Human Hairs don’t have a structured medulla ( Human Hairs don’t have a structured medulla ( some human hairs have no Medulla) some human hairs have no Medulla)

- Animal Medulla’s are quite structured- Animal Medulla’s are quite structured

Medulla patterns + other Medulla patterns + other animalsanimals

CatCat

RabbitRabbit

RabbitRabbit

Cuticle Cuticle Pattern >Pattern >

DeerDeer

HumanHuman

500500

Ovoid bodies found in Ovoid bodies found in Dog HairDog Hair

Ovoid bodies are Ovoid bodies are abundant in Cattle hairabundant in Cattle hair

Hair is made of ProteinHair is made of Protein

Hair is made of tight, closely packed Hair is made of tight, closely packed dead cells that are made up of myofibrils dead cells that are made up of myofibrils or bundles of helical keratinor bundles of helical keratin

Myofibril -Myofibril -

Bundles of protein filaments that make up Bundles of protein filaments that make up muscles and hairmuscles and hair

ProteinProtein

Long chain of amino acids Long chain of amino acids Make up muscles, skin, hair nails and all Make up muscles, skin, hair nails and all

the enzymes in your bodythe enzymes in your body

What are amino acids What are amino acids again?again?

Amino acids make up ProteinAmino acids make up Protein Keratin is protein and is therefore made Keratin is protein and is therefore made

up of amino acids in the form of a helixup of amino acids in the form of a helix

As hair grows, new As hair grows, new helical Keratin is added helical Keratin is added quicklyquickly

Papilla cells whip out 10 turns of the Papilla cells whip out 10 turns of the protein every second!!!protein every second!!!

Hair is extremely Hair is extremely STRONGSTRONG

Try to break a piece apart…Try to break a piece apart…

Hair gets strength from 3 Hair gets strength from 3 kinds of Chemical bondskinds of Chemical bonds

1) Individual Keratin Molecules are held 1) Individual Keratin Molecules are held together by Hydrogen Bondstogether by Hydrogen Bonds

1) Hydrogen Bonds form 1) Hydrogen Bonds form between the Amino Acids between the Amino Acids that make up Proteinsthat make up Proteins

3) DiSulfide Bridges3) DiSulfide Bridges

Link a Specific Amino Acid togetherLink a Specific Amino Acid together Cysteine ---CysteineCysteine ---Cysteine

When Hair stretches, These bridges break When Hair stretches, These bridges break apartapart

These are COVALENT bondsThese are COVALENT bonds

2) Hydrogen Bonds 2) Hydrogen Bonds between Helicesbetween Helices

Hair is stiff because of H bonds between Hair is stiff because of H bonds between individual Helices of Keratin. When your hair individual Helices of Keratin. When your hair gets wet, these H bonds break apart and your gets wet, these H bonds break apart and your hair gets limp and looses some of its structurehair gets limp and looses some of its structure

Why does WATER causeWhy does WATER cause

The H bonds in hair to beThe H bonds in hair to be

Rearranged?Rearranged?

Proteins have 4 levels of Proteins have 4 levels of organizationorganization

Primary level --- Sequence of amino Primary level --- Sequence of amino acids… polypeptides are thousands of acids… polypeptides are thousands of aa’s long… and correct order is crucialaa’s long… and correct order is crucial

Secondary levelSecondary level

Amino acids react with each other Amino acids react with each other forming forming

Alpha helicesAlpha helices Beta SheetsBeta Sheets

Third levelThird level

More foldingMore folding

Quaternary StructureQuaternary Structure

Many Poly peptides togetherMany Poly peptides together I.e. KeratinI.e. Keratin

Hemoglobin is a protein Hemoglobin is a protein that is made up of 4 that is made up of 4 polypeptidespolypeptides

Hair stretches…Hair stretches…

When you stretch hairs H- bonds When you stretch hairs H- bonds between helices break, allowing the helix between helices break, allowing the helix to extend.to extend.

Hair Can be Straight or Hair Can be Straight or CurlyCurly

Hair that is straight has a circular shapeHair that is straight has a circular shape

Hair that is curly has an elliptical hair Hair that is curly has an elliptical hair shaftshaft

Curly haired people also Curly haired people also have MORE disulfide have MORE disulfide bridges than straight bridges than straight haired peoplehaired people

When people get a Perm When people get a Perm (anent)… Heat is used to (anent)… Heat is used to Physically change hairPhysically change hair

2 lotions are applied2 lotions are applied First Lotion breaks their disulfide bridgesFirst Lotion breaks their disulfide bridges

When is hair evidence When is hair evidence important in a case?important in a case?

Animal or Human determination Animal or Human determination

Body area determinationBody area determination

Race association with hairRace association with hair

How are characteristics How are characteristics of Hair Determined?of Hair Determined?

A piece of hair cannot be individualized to a A piece of hair cannot be individualized to a particular head/personparticular head/person Rather it can be characterized and classifiedRather it can be characterized and classified

Comparative MicroscopeComparative Microscope Allows technician to compare two hairs side by sideAllows technician to compare two hairs side by side Two matching hairsTwo matching hairs

Hairs can show signs of Hairs can show signs of struggle:struggle:

This hair shows signs of forcible removalThis hair shows signs of forcible removal

Human Hair Could come Human Hair Could come from different spots on from different spots on the bodythe body

HeadHead Limb hairsLimb hairs Pubic HairsPubic Hairs FacialFacial

Eyebrows, Eyelashes and Beard hairsEyebrows, Eyelashes and Beard hairs

Head HairsHead Hairs

Longest hairs on bodyLongest hairs on body May show signs of treatment which may May show signs of treatment which may

indicate sex, as women more commonly treat indicate sex, as women more commonly treat hairhair

Must collect at least 25 sample comparison Must collect at least 25 sample comparison hairs from victim and suspect from all over hairs from victim and suspect from all over scalp to give an accurate characterizationscalp to give an accurate characterization

Collect both Telogen and Anagen hairsCollect both Telogen and Anagen hairs Tend to be most commonly foundTend to be most commonly found 100,000100,000 follicles on head follicles on head

Head Hair samples must Head Hair samples must be taken ASAPbe taken ASAP

Why?Why?

Hairs might show signs of Hairs might show signs of cuttingcutting

Which hair was cut by a razor?Which hair was cut by a razor? Which was cut with scissors?Which was cut with scissors? Which split on its own?Which split on its own?

Facial HairFacial Hair

Coarse in appearanceCoarse in appearance Usually contain wide Medulla’s ( large Usually contain wide Medulla’s ( large

Medulla Index’s)Medulla Index’s) May show signs of razor cutMay show signs of razor cut

Not usually as significant as Head Hair Not usually as significant as Head Hair ComparisonComparison

Limb Hairs (arms and Limb Hairs (arms and legs)legs)

Shorter in lengthShorter in length Arc ShapedArc Shaped Tapered endsTapered ends Cortex is granularCortex is granular Medulla is fragmented or absentMedulla is fragmented or absent

May be used to help corroborate other May be used to help corroborate other evidenceevidence

AxillaryAxillary

EyesEyes NoseNose UnderarmsUnderarms

Not routinely compared in Forensic Not routinely compared in Forensic ScienceScience

Pubic HairsPubic Hairs

One of the kinds of evidence where the One of the kinds of evidence where the mere presence will suggest foul play.mere presence will suggest foul play.

Pubic HairsPubic Hairs

Coarse, WiryCoarse, Wiry Diameter’s show a lot of variationDiameter’s show a lot of variation Buckling and tapered ends are commonBuckling and tapered ends are common

Pubic Hairs show Pubic Hairs show bucklingbuckling

Not all hairs are created Not all hairs are created equalequal

Pubic and Head hairs are given the most Pubic and Head hairs are given the most weightweight

Hair Can tell RaceHair Can tell Race

Caucasian HairCaucasian Hair

Colors vary from blonde - brown - blackColors vary from blonde - brown - black Fine - medium coarsenessFine - medium coarseness Hair Shaft’s may be round to ovalHair Shaft’s may be round to oval Pigment molecules are evenly distributedPigment molecules are evenly distributed

Hair from Asian descentHair from Asian descent

Regularly Coarse, Straight, and circular Regularly Coarse, Straight, and circular Hair shaft Hair shaft

Not curlyNot curly Hair Shaft is wider in diameter than other Hair Shaft is wider in diameter than other

racesraces Cuticle layer is significantly thickerCuticle layer is significantly thicker Pigment molecules are larger in size than Pigment molecules are larger in size than

Caucasian HairCaucasian Hair

Hair from African descentHair from African descent

Regularly curlyRegularly curly Hair Shaft appears more ovalHair Shaft appears more oval

Age and SexAge and Sex

Infant hair is finer and less defined than grown Infant hair is finer and less defined than grown peoplepeople

Elderly people may leave grey - non-pigmented Elderly people may leave grey - non-pigmented hairhair

If tissue is attached Sex can be determinedIf tissue is attached Sex can be determined Barr BodiesBarr Bodies DNA analysisDNA analysis mtDNAmtDNA

FiberFiber

A fiber is the smallest unit of fabric that A fiber is the smallest unit of fabric that could be left at a crime scenecould be left at a crime scene

Fibers can be natural or Fibers can be natural or artificialartificial

Natural fibers such as wool, cotton,silk, Natural fibers such as wool, cotton,silk, hemphemp

Artificial or man-made fibers can be Artificial or man-made fibers can be polyester, rayon, nylon or acylicspolyester, rayon, nylon or acylics

Fibers are generally used Fibers are generally used to place evidence that to place evidence that has transferred from a has transferred from a victim or suspects victim or suspects clothingclothing

When two people come in contact there When two people come in contact there is the chance that fibers is the chance that fibers Some clothing transfers better than othersSome clothing transfers better than others Some clothing accepts transfer particles Some clothing accepts transfer particles

better than othersbetter than others

Particles may also be Particles may also be transfers from other transfers from other sourcessources

From Rugs, beds, bedding material or From Rugs, beds, bedding material or other furnitureother furniture

What is an example of a type of fabric What is an example of a type of fabric that transfers or sheds well?that transfers or sheds well?

What is an example of a type of fabric What is an example of a type of fabric that picks up fibers well?that picks up fibers well?

Other factors that may Other factors that may influence particle influence particle transfer:transfer:

Length of time contact occurredLength of time contact occurred Nature of contact, violent contact may Nature of contact, violent contact may

yield more transferyield more transfer Length of time that passed since the Length of time that passed since the

alleged contact occurred alleged contact occurred

Depending on the Depending on the handling of the fabric handling of the fabric that transfer occurred on that transfer occurred on the clothing in questionthe clothing in question

There may not be any transferred fiber There may not be any transferred fiber left on the piece of clothing after even a left on the piece of clothing after even a single day.single day.

Cotton Is a commonly Cotton Is a commonly found natural fiberfound natural fiber

Cotton is grown from cotton plantsCotton is grown from cotton plants Cotton is commonly taken and milled at a Cotton is commonly taken and milled at a

textile milltextile mill Cotton fibers may have different lengths, Cotton fibers may have different lengths,

twisting patterns or colors depending on twisting patterns or colors depending on where where

Other natural textile Other natural textile fibers include flax (linen) fibers include flax (linen) and hempand hemp

Identification of a less common fiber Identification of a less common fiber would INCREASE the significance of the would INCREASE the significance of the evidenceevidence

Wool is another Wool is another commonly found fiber commonly found fiber used in clothing, used in clothing, blankets, rugs blankets, rugs

Wool originates from sheepWool originates from sheep Wool has a particularly knotted, twisted Wool has a particularly knotted, twisted

appearance up close under a microscopeappearance up close under a microscope

Wool evidenceWool evidence

Coarser wool fibers usually are found Coarser wool fibers usually are found making up rugs or blanketsmaking up rugs or blankets

Finer wool fibers make up clothingFiner wool fibers make up clothing

Wool can come from Wool can come from multiple sourcesmultiple sources

SheepSheep AlpacaAlpaca Cashmere goatsCashmere goats CamelCamel

Diameter of wool fiber and scales running Diameter of wool fiber and scales running along the outside of the cuticle would along the outside of the cuticle would help to determine the source of the wool.help to determine the source of the wool.

Wool v.s. Hemp under a Wool v.s. Hemp under a microscopemicroscope

Man-made or synthetic Man-made or synthetic fibers make up 1/2 of all fibers make up 1/2 of all fibers found in textile fibers found in textile millsmills You can determine a lot from how a fiber You can determine a lot from how a fiber

appears under the microscopeappears under the microscope Type of Type of FiberFiber Manufacturer evenManufacturer even

Unusual cross-sections of fiber increase Unusual cross-sections of fiber increase the probative valuethe probative value

Fiber colorFiber color

Comes from dyes in yarnComes from dyes in yarn Numerous colors - all fabrics take dye up Numerous colors - all fabrics take dye up

differentlydifferently An entire garment can be dyed after the An entire garment can be dyed after the

yarn itself was dyed adding to the greater yarn itself was dyed adding to the greater number of color differencesnumber of color differences

Fiber NumberFiber Number

Number of fibers found can increase the Number of fibers found can increase the significance of the evidencesignificance of the evidence

The greater the number of fibers found, The greater the number of fibers found, the more likely that contact occurred the more likely that contact occurred between these two peoplebetween these two people