Chapter 3 The Study f Hair By the end f this chapter yu will be able t: Identify the varius parts f a hair Describe variatins in the structure f the medulla, crtex, and cuticle Distinguish between human and nnhuman hair 1 All Rights Reserved Suth-Western / Cengage Learning 2012, 2009 Frensic Science: Fundamentals & Investigatins, Chapter 3
Chapter 3 The Study f Hair By the end f this chapter yu will be able t: Determine if tw examples f hair are frm the same persn Explain hw hair can be used in a frensic investigatin Calculate the medullary index fr a hair 2 Frensic Science: Fundamentals & Investigatins, Chapter 3
Hair as evidence Class evidence (if fllicle is nt attached) Secndary transfer left behind at crime scene, then transferred t anther lcatin. Animal hair in particular Des nt decmpse quickly Racial backgrund, drugs, txins, nutritinal deficiencies If fllicle is present DNA can be fund 3 Frensic Science: Fundamentals & Investigatins, Chapter 3
Histry f Hair Analysis 1. 1883: Alfred Swaine Taylr and Thmas Stevensn cvered hair in a frensic science text 2. 1910: Victr Balthazard and Marcelle Lambert published a cmprehensive study f hair 3. 1934: Dr. Sydney Smith, analyzed hairs side by side 4. Tday: chemical tests, neutrn activatin analysis, and DNA analysis 4 Frensic Science: Fundamentals & Investigatins, Chapter 3
The Functin f Hair Regulates bdy temperature When fluffed up, pckets f trapped air prvide insulatin Decreases frictin Prtects against sunlight 5 Frensic Science: Fundamentals & Investigatins, Chapter 3
The Structure f Hair A fllicle embedded in the skin prduces the hair shaft Papilla bld vessels that supply nutrients Sebaceus glands misturize hair Erectr muscle allws hair t stand upright Keratin prtein that strengthens hair 6 Frensic Science: Fundamentals & Investigatins, Chapter 3
The Structure f Hair Papilla 7 Frensic Science: Fundamentals & Investigatins, Chapter 3
Cuticles, Crtex, and Medulla Three layers the inner medulla the crtex the uter cuticle 8 Frensic Science: Fundamentals & Investigatins, Chapter 3
Types f Cuticle and Crtex Cuticle: the utermst layer ver-lapping scales that prtect the inner layers Crtex: Thickest layer Cntains mst f the pigment Distributin f pigment varies Usually denser nearer the cuticle 9 Frensic Science: Fundamentals & Investigatins, Chapter 3
Types f Medulla 10 Frensic Science: Fundamentals & Investigatins, Chapter 3
Types f Hair Buckled Blunt Duble Medulla A crss sectin: circular, triangular, irregular, r flattened Shape: influences the curl f the hair Texture: carse r fine 11 Frensic Science: Fundamentals & Investigatins, Chapter 3
Crss sectins f hair 12 Frensic Science: Fundamentals & Investigatins, Chapter 3
Types f Hair Human hair varies n the bdy Head circular r elliptical crss sectin Eyebrws circular c.s. but tapered ends Lashes -- circular c.s. but tapered ends Mustache -- thick with triangular c.s., duble medulla Beard -- thick with triangular c.s., duble medulla Underarms -- val r triangular c.s. Bdy hair -- val r triangular c.s. Pubic -- val r triangular c.s., buckling 13 Frensic Science: Fundamentals & Investigatins, Chapter 3
The Life Cycle f Hair 14 Hair prceeds thrugh 3 stages as it develps: Anagen stage: 1000 days, 80-90% hair actively grws cells arund the fllicle rapidly divide and depsit materials in the hair Catagen stage: 1-2 weeks, 2% Transitinal stage Fllicle shrinks and detaches frm papilla Telgen stage: 10-18% fllicle becmes drmant r rests, hair falls ut New hair may r may nt begin grwing
15 Frensic Science: Fundamentals & Investigatins, Chapter 3
Treated Hair Bleaching disturbs the scales n the cuticle remves pigment leaves hair brittle and yellwish Artificial sharp demarcatin Sun gradual mark Dyeing clrs the cuticle and the crtex Human hair grws at 1.3cm/mnth 16 Frensic Science: Fundamentals & Investigatins, Chapter 3
Racial Differences 17 Brad, racial grups d exhibit sme shared physical characteristics But NOT applicable t all individuals in these grups Therefre, Individual hairs CANNOT be assigned t any f these grups Lk at table 3-10 and cmpare racial trends (pg 55) Frensic Science: Fundamentals & Investigatins, Chapter 3
Animal Hair and Human Hair 18 Pigmentatin: animal hair is denser tward the medulla human hair tends t be denser tward the cuticle Animals vid bdies, banded pattern Humans same clr alng length Medulla: much thicker in animals Medullary index rati f diameter f medulla: diameter f entire hair Animal hair m.i. = 0.5 r greater Human hair m.i. =.33 r less
Medulla Index Animals vs. Humans 19 Frensic Science: Fundamentals & Investigatins, Chapter 3
Cmpare/cntrast human and animal hair What did yu ntice in yesterday s lab? 20 Frensic Science: Fundamentals & Investigatins, Chapter 3
Animal Hair and Human Hair Spinus Crnal Imbricate Animals: cuticle scales resemble petals (spinus rdents/bats) r a stack f crwns (crnal cats, seals, mink) r imbricate (dgs, deer, etc) Humans: cmmnly flattened and narrw (imbricate) 21 Frensic Science: Fundamentals & Investigatins, Chapter 3
Cllecting hair as trace evidence 22 Plucking, shaking, scraping surfaces Tape lift technique Large surfaces can be vacuumed then the cntents are filtered and examined Must be careful t prevent crss cntaminatin Hair samples are taken frm 6 majr bdy regins (50 frm head, 25 frm pubic) Head, eyebrws/eyelashes, beard/mustache, underarm, bdy hair, pubic hair
Using Hair in an Investigatin Macrscpic investigatins indicate Length, clr, curliness Micrscpic investigatins indicate Medulla pattern, crtex pigmentatin, scales/cuticle Cmparisn micrscpe particularly useful Phase cntrast (requires special bjective lens) micrscpy shws fine detail 23
Flurescence micrscpe Beam f light will fluresce (reemit light f a different wavelength) when certain chemicals are present Detects dye r ther hair treatments Electrn micrscpes use a beam f electrns instead f light 24 Frensic Science: Fundamentals & Investigatins, Chapter 3
Using Hair in an Investigatin Nte the verlapping scales and the pigment granules in the crtex. Electrn micrscpe 25 Frensic Science: Fundamentals & Investigatins, Chapter 3
Testing fr Substances in the Hair Shaft 26 Chemical tests Arsenic, lead, drugs Examining a hair shaft timeline fr expsure t txins Hair grws 1.3 cm/mnth, txins can be dated based n distance frm rt Neutrn Activatin Analysis (NAA) Detects cncentratins f substances Hair sample is bmbarded with neutrns Different elements give ff different gamma radiatin signals
Testing the Hair Fllicle 27 Micrscpic assessment Cst effective and quick If there is a micrscpic match, then samples will be frwarded fr further testing. Bld prtein test Determines bld type DNA analysis Identificatin with a high degree f cnfidence Individual evidence Frensic Science: Fundamentals & Investigatins, Chapter 3
Micrscpic Assessment Preparatin 28 Frensic Science: Fundamentals & Investigatins, Chapter 3
.............. Summary.... Hair functins t regulate temperature, reduce frictin, prtect frm light, and prduce sensry data. Hair cnsists f a (a) hair shaft prduced by a (b) fllicle embedded in the skin. The shaft cnsists f an uter cuticle, a crtex, and an inner medulla. Hair characteristics vary depending n lcatin n the bdy. 29 Frensic Science: Fundamentals & Investigatins, Chapter 3
.................. Summary Hair develpment has three stages: anagen, catagen, and telgen. Varius hair treatments prduce characteristic effects useful t frensic experts. Sme characteristics can be gruped int general racial categries. Frensic experts examine hair using chemicals, light, electrns, neutrns, and DNA sequencing. 30 Frensic Science: Fundamentals & Investigatins, Chapter 3