Objective: Yu will be able t describe the structure f hair. 1 Frensic Science: Fundamentals & Investigatins, Chapter 3
Apprximately 100 head hairs are shed by an individual each day. These hairs are shed n clthing and n items in the envirnment. Cntact between a victim and a suspect's envirnment can easily cause a secndary transfer f hair. Class Characteristic Why Study Hair? Can be used as crrbrative evidence 2/5/2015 2
What Can Be Learned frm Hair Human r animal? Race. Bdy area f rigin. Shed r frcibly remved. Disease. Cmparisn t knwn samples. 2/5/2015 3
The Skin 2/5/2015 4
The Skin Hair Pre Dermal Papillae Epidermis Dermis Hair fllicle Capillary Fat cells Erectr muscle Subcutaneus tissue 2/5/2015 5 Sweat Gland Nerve ending
The Structure f Hair 6 Frensic Science: Fundamentals & Investigatins, Chapter 3
Cuticles, Crtex, and Medulla 7 Frensic Science: Fundamentals & Investigatins, Chapter 3
Cuticle The utermst, translucent layer Prtects hair Flat cells layered in an verlapping frmatin that lks like shingles n a rf. Overlapping scales always pint twards tip end f hair Scale pattern allws fr differentiatin f species 8 Frensic Science: Fundamentals & Investigatins, Chapter 3
Three majr parts f Hair: Cuticle
Three majr parts f Hair: Cuticle Msaic Pectinate Imbricate Petal Diamnd Petal Chevrn
Crtex: Thickest layer Cntains mst f the pigment Cmpare clr, shape, distributin Lcatin where nature creates natural hair clring 11 Frensic Science: Fundamentals & Investigatins, Chapter 3
Medulla: Central cre f the hair. Cmpsed f sft keratin. Medullary index is hw much f diameter f hair medulla takes up Human <1/3 Other animals >1/2 Can vary even in same individual 12 Frensic Science: Fundamentals & Investigatins, Chapter 3
Medulla Index Animals vs. Humans 13 Frensic Science: Fundamentals & Investigatins, Chapter 3
Animal Hair and Human Hair Spinus Crnal Imbricate Animals: cuticle scales resemble petals (spinus) r a stack f crwns (crnal) Humans: cmmnly flattened and narrw (imbricate) 14 Frensic Science: Fundamentals & Investigatins, Chapter 3
Types f Medulla 15 Frensic Science: Fundamentals & Investigatins, Chapter 3
Human vs. Human All unknwns are cmpared t: KNOWN standards: clr, length, shape and diameter. Cncentratin f Medullary/ crtex pigments Grwth after Dyed r bleached? Dyed (clr) thrughut Bleached: pigments remved prvides a yellwish tint 2/5/2015 17
Hair Grwth Three develpmental stages: 1. Anagen phase, Active grwth phase 2. Catagen phase, Regressive phase 3. Telgen phase, Resting phase 2/5/2015 18
Hair Grwth Anagen has hair attached t fllicle fr cntinued grwth If this hair pulled usually has a piece f tissue attached DNA analysis can individualize Catagen has slight cntinued grwth Telgen is when grwth phase ends Hair will eventually pushed ut causing shedding Hair grws abut 1cm per mnth 2/5/2015 19
http://www.fbi.gv/hq/lab/fsc/backissu/july2000/deedric1.htm#hair%20evidence Shedding vs. Remval By Frce *Presence f fllicular tissue n rt *indicative f frcible remval *by a persn *by a cmb 2/5/2015 20
http://www.fbi.gv/hq/lab/fsc/backissu/july2000/deedric1.htm#hair%20evidence Hair Remval Naturally shed hairs, such as a head hair disldged thrugh cmbing, display undamaged, clubshaped rts. A hair frcibly remved frm the scalp will exhibit stretching and damage t the rt area. Frcibly remved hairs may have tissue attached. 2/5/2015 21
Bdy Area Determinatin Head Hairs: usually the lngest Characterized by a unifrm diameter Appearance f: Hair dyes, permanents, frsts, and ther chemical applicatins. Envirnmental alteratins: Sunlight Wind dryness A hair shwing buckling
Bdy Area Determinatin Pubic Hairs: Cnsiderable variatin exists between individuals in the ppulatin. Characteristics: generally carse and wiry with tapered tips They exhibit cnsiderable diameter variatin Often have a cntinuus t discntinuus medulla. Are nt subject t as much change ver time, and because f this, a sample taken a year r mre after a crime may still be suitable A hair shwing buckling
Facial Hairs Facial hairs are mre cmmnly called beard hairs r mustache hairs. Characteristics: are carse in appearance and can have a triangular crss sectin. Other characteristics include a wide medulla and a razr-cut tip.
Limb Hairs Hairs frm the legs and arms cnstitute limb hairs. Characteristics: shrter in length, arc-like in shape, and ften abraded r tapered at the tips. The pigment in limb hair is generally granular in appearance, and the medulla is trace t discntinuus.
Cllectin f Hair Evidence Questined hairs must be accmpanied with an adequate number f cntrl sample hairs frm victim frm thers suspected f depsiting hair at Crime scene Representative cntrl samples 50 full-length hairs frm all areas f scalp 24 full-length pubic hairs 26