1 Frensic Science: Fundamentals & Investigatins, 2e Cengage/NGL/Suth-Western 2016
Hair Analysis By the end f this chapter yu will be able t: 3.1 Identify the varius parts f a hair. 3.2 Describe variatins in the structure f the medulla, crtex, and cuticle. 3.3 Distinguish between human and nnhuman animal hair. 3.4 Determine if tw examples f hair are likely t be frm the same persn. 2 Frensic Science: Fundamentals & Investigatins, 2e Cengage/NGL/Suth-Western 2016
Hair Analysis By the end f this chapter yu will be able t: 3.5 Explain hw hair can be used in a frensic investigatin. 3.6 Calculate the medullary index fr a hair. 3.7 Distinguish hairs frm individuals belnging t brad racial categries. 3 Frensic Science: Fundamentals & Investigatins, 2e Cengage/NGL/Suth-Western 2016
Vcabulary cmparisn micrscpe crtex cuticle gas chrmatgraphy hair fllicle hair shaft keratin medulla melanin granules mitchndrial DNA (mtdna) nuclear DNA 4 Frensic Science: Fundamentals & Investigatins, 2e Cengage/NGL/Suth-Western 2016
Intrductin A hair withut the fllicle and its nuclear DNA cannt prvide individual evidence. Hair can yield class evidence. Chemical tests perfrmed n hair can reveal drugs, txins, heavy metals and nutritinal deficiencies. mtdna frm hair can reveal sme f a suspect s r victim s family relatinships. 5 Frensic Science: Fundamentals & Investigatins, 2e Cengage/NGL/Suth-Western 2016
6 Frensic Science: Fundamentals & Investigatins, 2e Cengage/NGL/Suth-Western 2016
Histry f Hair Analysis 1883: Alfred Swaine Taylr and Thmas Stevensn cvered hair in a frensic science text. 1910: Victr Balthazard and Marcelle Lambert published a cmprehensive study f hair. 1934: Dr. Sydney Smith, analyzed hairs side by side using a cmparisn micrscpe. Tday: Standard prcedures f hair analysis include micrscpic examinatin and DNA analysis. 7 Frensic Science: Fundamentals & Investigatins, 2e Cengage/NGL/Suth-Western 2016
The Functins f Hair Regulates bdy temperature Decreases frictin Prtects against sunlight Acts as a sense rgan Humans are brn with abut 5 millin hair fllicles. 8 Frensic Science: Fundamentals & Investigatins, 2e Cengage/NGL/Suth-Western 2016
The Structure f Human Hair Human hair cnsists f a fllicle and a shaft. 9 Frensic Science: Fundamentals & Investigatins, 2e Cengage/NGL/Suth-Western 2016
The Structure f Human Hair (cntinued) The hair shaft is made up f three layers: An inner medulla A crtex An uter cuticle 10 Frensic Science: Fundamentals & Investigatins, 2e Cengage/NGL/Suth-Western 2016
The Structure f Human Hair (cntinued) The cuticle is a transparent uter layer f the hair shaft. 11 Frensic Science: Fundamentals & Investigatins, 2e Cengage/NGL/Suth-Western 2016
Types f Medulla 12 Frensic Science: Fundamentals & Investigatins, 2e Cengage/NGL/Suth-Western 2016
Types f Hair In humans, hair varies frm persn t persn, and even varies depending n its lcatin n a particular persn. Fr an individual persn, hair can vary based n its lcatin n the bdy. T cmpensate fr incnsistencies that ccur, 50 hairs are usually cllected frm a suspect s r victim s head. 13 Frensic Science: Fundamentals & Investigatins, 2e Cengage/NGL/Suth-Western 2016
Hair Shapes Can be straight, curly, r kinky, depending n the crss-sectin, which may be rund, val, r crescent-shaped. Rund (Straight) Oval (Curly) Crescent mn (Kinky) 14 Frensic Science: Fundamentals & Investigatins, 2e Cengage/NGL/Suth-Western 2016
Hair frm Different Parts f the Bdy 15 Frensic Science: Fundamentals & Investigatins, 2e Cengage/NGL/Suth-Western 2016
The Life Cycle f Hair Hair prceeds thrugh three stages as it develps. Anagen stage; lasts apprximately 1000 days Grws abut 0.4 mm per day, r 1 cm per mnth; apprximately ne-half inch per mnth Catagen stage The hair stps grwing and the fllicle recedes. Telgen stage The hair fllicle is drmant and hair is easily lst. On average, 100 hairs are lst daily. 16 Frensic Science: Fundamentals & Investigatins, 2e Cengage/NGL/Suth-Western 2016
Treated Hair Hair can be treated in many different ways. 17 Frensic Science: Fundamentals & Investigatins, 2e Cengage/NGL/Suth-Western 2016
Ethnic r Ancestral Differences There are sme key physical characteristics that are assciated with hair f different ancestral grups. 18 Frensic Science: Fundamentals & Investigatins, 2e Cengage/NGL/Suth-Western 2016
Animal hair and Human Hair Animal hair and human hair have several differences including: The pattern f pigmentatin The medullary index The cuticle type 19 Frensic Science: Fundamentals & Investigatins, 2e Cengage/NGL/Suth-Western 2016
Medulla Index T determine the medullary index divide the diameter f the medulla by the diameter f the hair Medullary index fr human hair is generally less than 1/3. Fr animal hair, it is usually greater than 1/2. 20 Frensic Science: Fundamentals & Investigatins, 2e Cengage/NGL/Suth-Western 2016
Medulla Index 21 Frensic Science: Fundamentals & Investigatins, 2e Cengage/NGL/Suth-Western 2016
Hair Cuticles The cuticle f the hair shaft can help distinguish human hair frm ther animal hair. 22 Frensic Science: Fundamentals & Investigatins, 2e Cengage/NGL/Suth-Western 2016
Electrn Micrscpes Electrn micrscpes direct a beam f electrns at a sample. Electrn micrscpes prvide magnificatin f 50,000 times r mre. 23 Frensic Science: Fundamentals & Investigatins, 2e Cengage/NGL/Suth-Western 2016
Hair Examinatin and Testing 24 DNA is extracted and amplified using PCR. DNA is prfiled using an autmated prcess. Mitchndria DNA (mtdna) can be used t establish a genetic relatinship thrugh the mther. Nuclear DNA is lcated in the rt f the hair, nt the shaft Suspects can be excluded if their mtdna is nt cnsistent with the crime-scene mtdna. Frensic Science: Fundamentals & Investigatins, 2e Cengage/NGL/Suth-Western 2016
Summary Hair is a frm f evidence that has been used in frensic analysis since the late 19th century. Hair is a characteristic shared by all mammals and functins in temperature regulatin, reducing frictin, prtectin frm light, and as a sense rgan. Hair cnsists f a fllicle embedded in the skin that prduces the shaft. 25 Frensic Science: Fundamentals & Investigatins, 2e Cengage/NGL/Suth-Western 2016
Summary (cntinued) The shaft is cmpsed f the prtein keratin and cnsists f the uter cuticle, a crtex, and an inner medulla, mst f which can vary within and amng individuals and amng species. The shaft als has pigments and mitchndrial DNA. Hair varies in length, medulla type, and crsssectinal shape, depending n where n the bdy it riginates. Hair develpment is divided int three stages: anagen (grwth), catagen (resting), and telgen (drmancy). 26 Frensic Science: Fundamentals & Investigatins, 2e Cengage/NGL/Suth-Western 2016