Hair 1 Bertino History of Hair Analysis 1

Hair 1 Bertino

History of Hair Analysis 1. 1883: Alfred Swaine Taylor and Thomas 2 Stevenson covered hair in a forensic science text 2. 1910: Victor Balthazard and Marcelle Lambert published a comprehensive study of hair 3. 1934: Dr. Sydney Smith, analyzed hairs side by side 4. Today: chemical tests, neutron activation analysis, and DNA analysis Forensic Science: Fundamentals & Investigations, Chapter 3

The Function of Hair 3 o Regulates body temperature o Decreases friction o Protects against sunlight Forensic Science: Fundamentals & Investigations, Chapter 3

The Structure of Hair o o A follicle embedded in the skin produces the hair shaft Three layers: • • • 4 the inner medulla the cortex the outer cuticle Forensic Science: Fundamentals & Investigations, Chapter 3

The Structure of Hair 5 Forensic Science: Fundamentals & Investigations, Chapter 3

6 Forensic Science: Fundamentals & Investigations, Chapter 3

Cuticles, Cortex, and Medulla 7 Forensic Science: Fundamentals & Investigations, Chapter 3

Types of Cuticle and Cortex o Cuticle: • • o Cortex: • • 8 the outermost layer over-lapping scales that protect the inner layers Thickest layer Contains most of the pigment Distribution of pigment varies Usually denser nearer the cuticle Forensic Science: Fundamentals & Investigations, Chapter 3

Animal Hair and Human Hair Spinous o o 9 Coronal Imbricate Animals: cuticle scales resemble petals (spinous) or a stack of crowns (coronal) Humans: commonly flattened and narrow (imbricate) Forensic Science: Fundamentals & Investigations, Chapter 3

Coronal 10 Forensic Science: Fundamentals & Investigations, Chapter 3

Spinous 11 Forensic Science: Fundamentals & Investigations, Chapter 3

Imbricate 12 Forensic Science: Fundamentals & Investigations, Chapter 3

Types of Medulla 13 Forensic Science: Fundamentals & Investigations, Chapter 3

Medulla Index— Animals vs. Humans 14 Forensic Science: Fundamentals & Investigations, Chapter 3

Types of Hair Buckled o o o 15 Blunt Double Medulla A cross section: circular, triangular, irregular, or flattened Shape: influences the curl of the hair Texture: coarse or fine Forensic Science: Fundamentals & Investigations, Chapter 3

Types of Hair Human hair varies on the body • • 16 Head Eyebrows Lashes Mustache Beard Underarms Body hair Pubic Forensic Science: Fundamentals & Investigations, Chapter 3

The Life Cycle of Hair proceeds through 3 stages as it develops: o Anagen stage: • • o Catagen stage: • o hair grows and changes Telogen stage: • 17 hair actively grows cells around the follicle rapidly divide and deposit materials in the hair follicle becomes dormant Forensic Science: Fundamentals & Investigations, Chapter 3

18 Forensic Science: Fundamentals & Investigations, Chapter 3

Treated Hair o Bleaching • • • o 19 disturbs the scales on the cuticle and removes pigment leaves hair brittle and yellowish Dyeing colors the cuticle and the cortex Forensic Science: Fundamentals & Investigations, Chapter 3

Racial Differences Broad, racial groups do exhibit some shared physical characteristics o But NOT applicable to all individuals in these groups Therefore, o Individual hairs CANNOT be assigned to any of these groups o 20 Forensic Science: Fundamentals & Investigations, Chapter 3

Animal Hair and Human Hair o Pigmentation: • animal hair is denser toward the medulla • human hair tends to be denser toward the cuticle o Banded Color Patterns: • • o 21 possible in animals not in humans Medulla: much thicker in animals Forensic Science: Fundamentals & Investigations, Chapter 3

Using Hair in an Investigation o Macroscopic investigations indicate • • • o Phase contrast microscopy shows • o 22 length color curliness presence of dye or other treatments Electron microscopes yield yet more detail Forensic Science: Fundamentals & Investigations, Chapter 3

Using Hair in an Investigation Note the overlapping scales and the pigment granules in the cortex 23 Forensic Science: Fundamentals & Investigations, Chapter 3

Testing for Substances in the Hair Shaft o Chemical tests • o Examining a hair shaft • o timeline for exposure to toxins Neutron Activation Analysis (NAA) • 24 presence of various substances concentrations of substances Forensic Science: Fundamentals & Investigations, Chapter 3

Testing the Hair Follicle o Microscopic assessment • o Blood test • o Determine blood type DNA analysis • 25 Cost effective and quick Identification with a high degree of confidence Forensic Science: Fundamentals & Investigations, Chapter 3

Collection and Preservation o o 26 As a general rule, forensic hair comparisons involve either head hair or pubic hair. The collection of 25 full-length hairs from all areas of the scalp will normally ensure a representative sampling of head hair. Forensic Science: Fundamentals & Investigations, Chapter 3

Microscopic Assessment o 27 Preparation Forensic Science: Fundamentals & Investigations, Chapter 3