FORENSIC HAIR ANALYSIS 1 INTRODUCTION A hair without

FORENSIC HAIR ANALYSIS 1

INTRODUCTION • A hair without the follicle and its nuclear DNA cannot provide individual evidence. • Hair can yield class evidence. • Chemical tests performed on hair can reveal drugs, toxins, heavy metals and nutritional deficiencies. • mt. DNA from hair can reveal some of a suspect’s or victim’s family relationships. • Secondary Transfer is very common in animal hairs • Hair has a tough outer covering that means it doesn’t easily decompose Forensic Science: Fundamentals & Investigations, 2 e Chapter 3 All rights Reserved Cengage/NGL/South-Western © 2016

Chemical tests can provide a history of drugs and toxins Forensic Science: Fundamentals & Investigations, 2 e Chapter 3 3

HISTORY OF HAIR ANALYSIS 1883: Alfred Swaine Taylor and Thomas Stevenson covered hair in a forensic science text. It included drawings of human hair under the microscope. 4

HISTORY OF HAIR ANALYSIS o 1910: Victor Balthazard and Marcelle Lambert published a comprehensive study of hair called “The Hair of Men and Animals. ” It included microscopic studies of hairs from many different animals. Forensic Science: Fundamentals & Investigations, 2 e Chapter 3 5

HISTORY OF HAIR ANALYSIS 1934: Dr. Sydney Smith, analyzed hairs side by side using a comparison microscope. Helped solve the case of a murder of an eight year old girl. Forensic Science: Fundamentals & Investigations, 2 e Chapter 3 All rights Reserved Cengage/NGL/South-Western 6 © 2016

HISTORY OF HAIR ANALYSIS Today: Standard procedures of hair analysis include microscopic examination and DNA analysis. Forensic Science: Fundamentals & Investigations, 2 e Chapter 3 7

THE FUNCTIONS OF HAIR • Regulates body temperature • Decreases friction • Protects against sunlight • Acts as a sense organ • Humans are born with about 5 million hair follicles. (2% on on the head and they decrease with age!) Forensic Science: Fundamentals & Investigations, 2 e Chapter 3 All rights Reserved Cengage/NGL/South-Western 8 © 2016

THE STRUCTURE OF HUMAN HAIR • Human hair consists of a follicle and a shaft. • Follicle – club shaped structure in the skin • Papilla – network of blood vessels that supply nutrients to grow the hair • Sebaceous gland – secretes oil that conditions hair • Erector muscle – causes the hair to stand upright • Nerve cells – wind around the follicle and stimulate the muscle in response to environment stimuli Forensic Science: Fundamentals & Investigations, 2 e Chapter 3 All rights Reserved Cengage/NGL/South-Western 9 © 2016

THE STRUCTURE OF HUMAN HAIR (CONTINUED) • The hair shaft is composed of a strong and flexible protein called keratin. It is made up of three layers: – An inner medulla – A cortex – An outer cuticle Forensic Science: Fundamentals & Investigations, 2 e Chapter 3 All rights Reserved 10 © 2016 Cengage/NGL/South-Western

STRUCTURE - CUTICLE • The cuticle is a transparent outer layer of the hair shaft. • Made of overlapping scales that all point outward from the scalp (proximal end) to the edge (distal end) • Knowing the “younger” side of the hair makes the timeline of drugs and toxins detected by analysis more valid. Forensic Science: Fundamentals & Investigations, 2 e Chapter 3 All rights Reserved 11 © 2016 Cengage/NGL/South-Western

STRUCTURE - CORTEX • Contains the melanin (pigment) • The granule distribution can vary from person to person Forensic Science: Fundamentals & Investigations, 2 e Chapter 3 All rights Reserved 12 © 2016 Cengage/NGL/South-Western

STRUCTURE - MEDULLA • Center of the hair • Can be a hollow tube • Patterns of pigmentation are classified into 5 groups Forensic Science: Fundamentals & Investigations, 2 e Chapter 3 All rights Reserved 13 © 2016 Cengage/NGL/South-Western

TYPES OF HAIR • In humans, hair varies from person to person, and even varies depending on its location on a particular person. • For an individual person, hair can vary based on its location on the body. • To compensate for inconsistencies that occur, 50 hairs are usually collected from a suspect’s or victim’s head. Forensic Science: Fundamentals & Investigations, 2 e Chapter 3 All rights Reserved Cengage/NGL/South-Western © 2016 14

HAIR FROM DIFFERENT PARTS OF THE BODY 1. Head hair – Generally circular or elliptical in the cross section 2. Eyebrows and eyelashes – Also circular but often have tapering ends 3. Beard and mustache hair – Tend to be thick and triangular in cross section, usually coarse and may have double medulla 4. Underarm hair 5. Auxiliary or body hair – Tends to be oval or triangular, have blunt tips and generally are frayed at the ends 6. Pubic hair – Tends to be oval or triangular, has irregular buckling along the shaft Forensic Science: Fundamentals & Investigations, 2 e Chapter 3 All rights Reserved 15 © 2016 Cengage/NGL/South-Western

THE LIFE CYCLE OF HAIR Hair proceeds through three stages as it develops. • Anagen stage – Lasts approximately 1000 days – 80 -90% of human hair is in this stage – Active growth with cells around the follicle rapidly dividing • Catagen stage – The hair stops growing and the follicle recedes. – 2% of human hair is in this stage – Sometimes turns gray at this stage • Telogen stage – The hair follicle is dormant and hair is easily lost. – 10 -18% of human hair is in this stage • There is no pattern as to which hairs on the head are in a particular stage at any time. Forensic Science: Fundamentals & Investigations, 2 e Chapter 3 All rights Reserved Cengage/NGL/South-Western © 2016 16

THE LIFE CYCLE OF HAIR Forensic Science: Fundamentals & Investigations, 2 e Chapter 3 All rights Reserved 17 © 2016 Cengage/NGL/South-Western

TREATED HAIR • Hair can be treated in many different ways. • Bleached – removes pigment granules and gives hair a yellowish color. Also makes hair brittle and can disturb the scales on the cuticle. – Artificial bleaching: sharp demarcation along the hair – Sun bleaching: leaves a gradual mark • Dyeing hair – changes the color of the hair shaft. The cuticle and cortex both take on the color of the dye. – Can sometimes estimate when the hair was las color-treated. – Human hair grows at about 1. 3 cm per month (. 44 mm per day) Forensic Science: Fundamentals & Investigations, 2 e Chapter 3 All rights Reserved 18 © 2016 Cengage/NGL/South-Western

ETHNIC OR ANCESTRAL DIFFERENCES • There are some key physical characteristics that are associated with hair of different ancestral groups. • These characteristics are only generalities and may not apply to individuals of certain races. Forensic Science: Fundamentals & Investigations, 2 e Chapter 3 All rights Reserved 19 © 2016 Cengage/NGL/South-Western

ANIMAL HAIR AND HUMAN HAIR • Animal hair and human hair have several differences including: – The pattern of pigmentation – The medullary index – The cuticle type • Pigmentation in human hair tends to be denser toward the cuticle while animals it is more often towards the medulla • Human hairs are generally one consistent color – animal hair can change abruptly in a banded pattern. • Animal medulla are much larger than it is in humans • The ratio of the diameter of the medulla to the diameter of the entire hair is known as the “medullary index. ” If the medullary index is. 5 or greater the hair came from an animal. If it is. 33 or less than the hair is from a human Forensic Science: Fundamentals & Investigations, 2 e Chapter 3 All rights Reserved 20 © 2016 Cengage/NGL/South-Western

ANIMAL HAIR AND HUMAN HAIR • The ratio of the diameter of the medulla to the diameter of the entire hair is known as the “medullary index. ” If the medullary index is. 5 or greater the hair came from an animal. If it is. 33 or less than the hair is from a human Forensic Science: Fundamentals & Investigations, 2 e Chapter 3 All rights Reserved 21 © 2016 Cengage/NGL/South-Western

HAIR CUTICLES • The cuticle of the hair shaft can help distinguish human hair from other animal hair. Forensic Science: Fundamentals & Investigations, 2 e Chapter 3 All rights Reserved 22 © 2016 Cengage/NGL/South-Western