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 3 Frensic Science: Fundamentals & Investigatins, Chapter 3
The Functin f Hair Regulates bdy temperature Decreases frictin Prtects against sunlight 4 Frensic Science: Fundamentals & Investigatins, Chapter 3
The Structure f Hair 5 Frensic Science: Fundamentals & Investigatins, Chapter 3
The Structure f Hair A fllicle embedded in the skin prduces the hair shaft Three layers (illustrated abve): the inner medulla the crtex the uter cuticle 6 Frensic Science: Fundamentals & Investigatins, Chapter 3
Bilgy f Hair Hair is cmpsed f the prtein keratin, which is als the primary cmpnent f finger and te nails. Hair is prduced frm a structure called the hair fllicle. Humans develp hair fllicles during fetal develpment, and n new fllicles are prduced after birth. Hair clr is mstly the result f pigments, which are chemical cmpunds that reflect certain wavelengths f visible light. Hair shape (rund r val) and texture (curly r straight) is influenced heavily by genes. The physical appearance f hair can be affected by nutritinal status and intentinal alteratin (heat curling, perms, straightening, etc.). The bdy area (head, arm, leg, back, etc.) frm which a hair riginated can be determined by the sample s length, shape, size, clr, and ther physical characteristics. In rder t test hair evidence fr DNA, the rt must be present. Surces: http://library.thinkquest.rg/04ct/00206/lessn.htm#t_hair & http://www.fbi.gv/hq/lab/fsc/backissu/july2000/deedric1.htm#index%20(hairs)
Hair Structure Hair is cmpsed f three principal parts: Cuticle uter cating cmpsed f verlapping scales Crtex prtein-rich structure arund the medulla that cntains pigment Medulla central cre (may be absent) The structure f hair has been cmpared t that f a pencil with the medulla being the lead, the crtex being the wd and the cuticle being the paint n the utside. http://library.thinkquest.rg/04ct/00206/lessn.htm#t_hair
Cuticles, Crtex, and Medulla 9 Frensic Science: Fundamentals & Investigatins, Chapter 3
Types f Cuticle and Crtex 10 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 Made up f keratin Frensic Science: Fundamentals & Investigatins, Chapter 3
Hair Structure Cuticle The cuticle varies in: Its scales, Hw many there are per centimeter, Hw much they verlap, Their verall shape, and Hw much they prtrude frm the surface Its thickness, and Whether r nt it cntains pigment. Characteristics f the cuticle may be imprtant in distinguishing between hairs f different species but are ften nt useful in distinguishing between different peple. Inf: http://library.thinkquest.rg/04ct/00206/lessn.htm#t_hair Image: http://www.hairdressersus.cm/micr/image5b.jpg
Hair Structure Crtex The crtex varies in: Thickness Texture Clr Distributin f the crtex is perhaps the mst imprtant cmpnent in determining frm which individual a human hair may have cme. Micrscpic examinatin can als reveal the cnditin and shape f the rt and tip. Inf: http://library.thinkquest.rg/04ct/00206/lessn.htm#t_hair Image: http://www.extrapersnality.cm/hair.html
Hair Structure Medulla The medulla may vary in: Thickness Cntinuity - ne cntinuus structure r brken int pieces Opacity - hw much light is able t pass thrugh it It may als be absent in sme species. Like the cuticle, the medulla can be imprtant fr distinguishing between hairs f different species, but ften des nt lend much imprtant infrmatin t the differentiatin between hairs frm different peple. http://library.thinkquest.rg/04ct/00206/lessn.htm#t_hair http://www.bfr.net/images/whatis/figures/fig.%203%20with%20captin.jpg
Types f Medulla 14 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 15 Frensic Science: Fundamentals & Investigatins, Chapter 3
Frensic scientists distinguish six types f hair n human bdy Human hair varies n the bdy Head Eyebrws and Lashes Mustache and Beard Underarms Bdy hair r auxiliary hair Pubic Each has its wn shape and charactyeristics 16 Frensic Science: Fundamentals & Investigatins, Chapter 3
The Life Cycle f Hair Hair prceeds thrugh 3 stages as it develps: Anagen stage: hair actively grws cells arund the fllicle rapidly divide and depsit materials in the hair Catagen stage: hair grws and changes Telgen stage: fllicle becmes drmant 17 Frensic Science: Fundamentals & Investigatins, Chapter 3
Treated Hair Bleaching disturbs the scales n the cuticle and remves pigment leaves hair brittle and yellwish Dyeing clrs the cuticle and the crtex 18 Frensic Science: Fundamentals & Investigatins, Chapter 3
Racial Differences 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 19 Frensic Science: Fundamentals & Investigatins, Chapter 3
Animal Hair and Human Hair 20 All mammals have hair. Its main purpse is t: regulate bdy temperature-t keep the bdy warm by insulating it. Pigmentatin: animal hair is denser tward the medulla human hair tends t be denser tward the cuticle Banded Clr Patterns: pssible in animals nt in humans Medulla Index: much thicker in animals Frensic Science: Fundamentals & Investigatins, Chapter 3
Medulla Index Animals vs. Humans 21 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) 22 Frensic Science: Fundamentals & Investigatins, Chapter 3
Using Hair in an Investigatin Hair is Class Evidence 23 Hair can adhere t clthes, carpets and many ther surfaces and be transferred t ther lcatins. This is called: secndary transfer Macrscpic investigatins indicate length clr curliness Phase cntrast micrscpy shws presence f dye r ther treatments Electrn micrscpes yield yet mre detail Frensic Science: Fundamentals & Investigatins, Chapter 3
Using Hair in an Investigatin Nte the verlapping scales and the pigment granules in the crtex 24 If a hair is frcibly remved frm a victim, the entire hair fllicle may be present. This is called a fllicular tag. Frensic Science: Fundamentals & Investigatins, Chapter 3
Testing fr Substances in the Hair Shaft Chemical tests Since hair grws ut f the skin, chemicals that the skin absrbs can becme: incrprated int hair, Ingested r absrbed txins can be detected by chemical analyses f hair. These ingested r absrbed txins include: arsenic, drugs, lead. Examining a hair shaft timeline fr expsure t txins Neutrn Activatin Analysis (NAA) cncentratins f substances 25 Frensic Science: Fundamentals & Investigatins, Chapter 3
Testing the Hair Fllicle 26 Micrscpic assessment Cst effective and quick pattern f the medulla. types f scales n the cuticle. pigmentatin f the crtex. Bld test Determine bld type DNA analysis Identificatin with a high degree f cnfidence Frensic Science: Fundamentals & Investigatins, Chapter 3
Micrscpic Assessment Preparatin 27 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. 28 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. 29 Frensic Science: Fundamentals & Investigatins, Chapter 3