Hair & Fiber - MS. Rivera's Science Class

Hair & Fiber - MS. Rivera's Science Class

Hair & Fiber Come in and get your notebooks out. We have notes today! t i Un #5 air

Part 1 : H Function of Hair? All Mammals have hair. Hair is used for many different reasons including: Regulating Body Temperature Sense Organ Protection from the Elements and Sunlight. When a mammals hair is dense, it is referred to as Fur.

Hair is considered CLASS EVIDENCE. Human hair is one of the most frequently found pieces of evidence at the scene of a violent crime. It can provide a link between the criminal and the crime. Hair as Evidence? Caucasian or White hair From hair one can determine: If the source is human or animal

Race (sometimes) Origin of the location on the sources body Whether the hair was forcibly removed If the hair has been treated with chemicals If drugs have been ingested Asian or Indian hair African Black Hair

Hair Analysis Typical hair that is found: Scalp Beard Eyelash Body hair Pubic Hair What Can Hair Examination Show: Finding hair shows there has been physical contact between a victim and perpetrator

When found, it is submitted to the lab with standard samples It can provide strong evidence for placing someone at the scene First step of examination begins with color, structure, and morphology Then progresses to DNA testing The Structure of Hair Hair can be broken into 2 parts: the Follicle and the Hair Shaft. A follicle is the part of the skin that grows hair.

Hair grows from its root, continues into the shaft, and terminates at the tip end The Hair Shaft is made up of 3 layers: the Cortex, Cuticle, and Medulla. Hair Shaft Forensic Scientists Examine The Hair Shaft Hair Shaft Components Cuticleoutside covering, made of

overlapping scales Cortexinner layer made of keratin and imbedded with pigment; also contains air sacs called cortical fusi Medullainside layer running down the center of the cortex A Basis for Comparison. like. A open pencil can remind us of what the hair shaft will look

Cortex Medulla Cuticle Hair Shaft Ends Burned Cut Razored

Split The Cuticle Gives hair resistance to chemical breakdown and retains its structural features Overlapping scales always point towards tip end of hair. Scale pattern allows for differentiation of species The Cortex Is found within the cuticle and gives the hair its shape. It is embedded with the pigment granules

melanin that give hair its color Color, shape, and distribution of these granules provide important comparison points Cortical fusiair spaces, usually found near the root but may be found throughout the hair shaft The Medulla Looks like a central canal running thru the hair Medullary index measures the diameter of the medulla to that of the hair shaft (fraction)

In humans, it is less than 1/3, most other animals is 1/2 or greater Medulla may be patterned (unisereal, lattice, multisereal, vacuolated), amorphous (continuous, interrupted, fragmented), or absent Human head hairs: generally none or fragmented Exception is Asian race: usually continuous The Medulla

Most animals have continuous or interrupted Humans and some animals have medulla that are cylinder shaped Other animals have medulla with patterns Cat has what looks like a string of pearls Deer-circular cells running whole length & width There is a database of the 35 most common animal hairs found at crime scenes The Medulla

Humans Humans versus common animals versus common animals Hair Shape Can be straight, curly or kinky depending

on the cross-section, which may be round, oval or crescentshaped Round (Straight) Oval (Curly) Crescent moon (Kinky)

Types of Hair Scalp: has a uniform diameter in cross-section Beard: coarse, curved, and when viewed in cross-section has a distinctive triangular shape Eyebrow, nose, ear, and eyelid: shorter and stubbier than scalp hair and have wide medullas Axillary: have unevenly distributed pigments; end in a fine point when uncut Auxiliary: oval or triangular, depending on whether the body region has been regularly shaved Pubic: oval or triangular The Root

Human head hair grows in 3 stages: Anagen phase (initial growth): lasts up to six years; root is attached to follicle for continued growth; flame-shaped appearance. When pulled out, it will have a follicular tag -This tissue has the richest source of DNA and can be analyzed for individualization Catagen phase: Hair continues to grow but at a slower rate which can last 2 to 3 weeks; roots have an elongated appearance due to shrinking and hair being pushed out follicle Telogen phase: hair growth ends and root takes a club-shape; in 2 to 6 months, the hair will be pushed out and shed Hair Comparison

Color Length Diameter Distribution, shape and color intensity of pigment granules Dyed hair has color in cuticle and cortex Bleaching removes pigment and gives a yellow tint

Scale types Presence or absence of medulla Medullary type Medullary pattern Medullary index ID and Comparison of Hair Prime purpose to examine hair is to see whether it is human or animal or to determine whether hair retrieved at a crime scene compares with a person

in question In most cases, comparison is done on head and pubic hair Scale structure, medullary index, and medullary shape are important in hair ID Factors in Comparison of Hair Animal is usually distinguished from human hair easily Human hair comparisons must be done with caution Hair has variable characteristics not only from person to person but also within a single person Criminalist is interested in matching color, length, diameter Others are the presence/absence of medulla, distribution, shape, and color

intensity of granules in the cortex Microscope may distinguish dyed/bleached vs natural hair Dyed color is present in the cuticle and cortex Bleaching removes pigment from hair and leaves a yellowish tint If hair has grown from last bleaching or dye, the new hair will have a distinct color difference An estimate of time can since dyeing or bleaching can be made because hair grows about 1.3 cm a month Microscopic Exam of Hair A comparison microscope allows the examiner to view the questioned and known hair together, side by side

Comparison may include or exclude questioned hairs against standard hairs This is questionable because it is dependent on the skills and integrity of the analyst If it cant be excluded, DNA analysis must be carried out FBI published errors made by microscopic exam Between 1996 and 2000, 11 percent of hairs ( 9 out of 80)in which FBI found a pos microscopic match between questioned and standard hairs were found to be nonmatches when subjected to DNA analysis Can the body area in which hair originated

be determined? Normally is easy Scalp hairs show little diameter variation & have more uniform distribution of pigment Pubic hair is short and curly with wide variation in diameter, usually have continuous medullae Beard hair is coarse, triangular in cross-section, have blunt tips from shaving Can age and sex be determined? Age cannot except for infant hair Infant hair tends to be fine, short, and has fine pigmentation

Presence of dye or bleach may offer some clues as to which sex the individual is Recovery of nuclear DNA (passed down to us by both parents) from tissue adhering to hair or from root structure of hair will determine sex Is it possible to determine if hair was forcibly removed? Yes, exam may determine whether the hair shed or was pulled from skin Root with follicular tissue indicates it was pulled out by a person or by brushing hair Hair naturally shedding has a bulbous-shaped root free

of tissue Sometimes, the root does not possess tissue even thought the hair was pulled out Hair pulled quickly are more likely to have tissue Hair removed slowly will not Pulled Forcibly removed Shed

Are efforts being made to individualize human hair? Can link human hair to a particular person by nuclear DNA in the hair root or follicular tissue Follicular tissue is the richest source of DNA associated with hair Examiners have a higher success rate in extracting DNA from hair roots in the anagen phase or from anagen entering catagen Telogen phase has an inadequate amount of DNA When there is no tissue or root, there is mitochondrial DNA (found in cellular material outside the nucleus) This is passed down to us by our mother only

Many more copies are located in our cells than nuclear DNA Success rate of finding and typing Mitochondrial is greater Can DNA individualize a human hair? Nuclear DNA can Mitochondrial cannot but can exclude a significant portion of a population as potential contributors Combination of a positive microscopic exam and nuclear or mitochondrial DNA strongly links a questioned hair and standard BUT mitochondrial DNA cant distinguish hairs from different individuals who are

maternally related Collection/Preservation Questioned hairs must be submitted with an adequate number of standard samples Questioned and standards must come from same body location from victim, suspects, and other who may have deposited hair at the scene. Comparisons will usually involve head or pubic hair Head: collect 50 full-length hairs from all areas of scalp Pubic: collect 24 full-length pubic hair In rape cases: Comb pubic area with clean comb to remove all loose hair before sampling for standard samples

Comb should be packaged in separate envelope Autopsy: hair is always collected just in case Hair toxicology Advantages: Easy to collect and store Is externally available Can provide information on the individuals history of drug use or of poisoning. Collections must be taken from different locations on the body to get an accurate timeline.

Hair Toxicology Napoleon died in exile in 1821. By analyzing his hair, some investigators suggest he was poisoned by the deliberate administration of arsenic; others suggest that it was vapors from the dyes in the wallpaper that did him in.

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