1. HAIR & FIBRES

2. Let’s take a closer look at hairs and fibres ...
Hair and fibres
General characteristics of fibres
Hair and fibres used as clues
Let’s take a closer look at hairs and fibres ...

3. Scanning electron microscope
A Hair as viewed under a Scanning Electron Microscope

4. BROWN HAIR
Brown hair through a microscope
80x magnification

5. Hair with root
Naturally shed hairs, such as a head hair dislodged through combing, display undamaged, club-shaped roots.

6. Forcibly removed hair
A hair forcibly removed from the scalp will exhibit stretching and damage to the root area.

7. Forcibly removed hair
Forcibly removed hairs may have tissue attached.

8. General characteristics
Hairs and fibres may be transferred from the suspect or the suspect’s clothes to the victims’ and vice versa eg 1 - a pedestrian struck by a vehicle may leave hairs and fibres on the suspect’s vehicle bumper or eg 2 - or carpet fibres attaching to a suspect’s shoes
Hair with roots may provide individual DNA evidence 
Hair also has characteristics.  There are 14 different elements that can be identified in a hair sample   
fibres are usually collected from clothing, carpeting, furniture, beds, and blankets
There are over a thousand known fibres, and several thousand known dye formulas

9. Glossary
Light microscopy – A microscope which has light shining on the sample and being reflected into the eye piece
Medulla – the central structure of a hair
Abdomen – the body eg lower abdomen = belly
Morphology – how something looks
Cuticle: The cuticle is the outermost protective covering of the hair
Cortex: The cortex is located beneath the cuticle of the hair
Root: The root is the part of the hair in the follicle that is below the surface of the skin
Follicle: The hair follicle is a pocket located beneath the surface of the skin from which the hair grows
Shaft: The shaft is the part of the hair that is visible above the skin’s surface.

10. What characteristics help investigators identify hair samples?
Hair Evidence
Hair is one of the most common forms of trace evidence. The examination of human hairs in the forensic laboratory is conducted through the use of light microscopy. The examination involves the identification of sample hairs and the comparison of sample and known hairs.
A scientist using a comparison-light microscope
View of matching hairs using a comparison-light microscope
Is it human or animal? Are there any differences you know of between human and animal hair? Describe the differences you think there are between animal and human hair. You will be comparing hair in a later activity.
What characteristics help investigators identify hair samples?

11. Homework For your next class bring in 3 samples of hair
Try to get hair from:
various animals or
from people who have dyed hair or
From people who have hair cut at different lengths or
Hair from different areas of the body ie arm, leg, nose (eww), eyelash

12. I am not an animal…
The first step in the hair examination process is to determine whether the hair in question originated from an animal or a human.
If the hair originated from an animal, it is possible to further identify it to a particular species of animal. It is not possible to identify hairs to a specific animal to the exclusion of other similar animals. An example of this occurs when dog hairs can be associated to a particular breed but cannot be identified to a specific dog within that breed.

13. Hair type
Scalp hair has consistent diameter and uniform distribution of pigment
Pubic hairs have continuous medullae
Beard hairs have triangular cross-sections
Eyebrow hair has decreasing diameter from root to tip

14. Biology of Hair
Hair is an outgrowth of the skin and is produced from a structure called the hair follicle. Humans develop hair follicles during fetal development, and no new follicles are produced after birth. Hair is composed of the protein keratin. Keratin is also the primary component of finger and toe nails.
Hair color is mostly the result of pigments, which are chemical compounds which reflect certain wavelengths of visible light. Hair color may also be influenced by the optical effects of light reflecting and bouncing off the surfaces of the different hair.
Sources: &

15. Razor cut hair

16. Hair with cut tip

17. Label the hair shaft and root on a rough drawing in your books
Also label the dermis and epidermis etc (from the finger print powerpoint)

18. Hair shape (round or oval) and texture (curly or straight) is influenced heavily by genes. Nutritional status and intentional alteration (heat curling, "perms") can affect the physical appearance of hair.
The body area from which a hair originated can be determined by the sample’s length, shape, size, color, stiffness, curliness, microscopic appearance, pigmentation, and the appearance of the medulla. Hairs that exhibit similar characteristics from different areas on the body are often referred to as body hairs and include hairs found on the upper legs, lower abdomen, and back.

19. Hair is composed of three principal parts:
Cuticle – outer coating composed of overlapping scales
Cortex – protein-rich structure around the medulla that contains pigment
Medulla – central core (may be absent)
The structure of hair has been compared to that of a pencil with the medulla being the lead, the cortex being the wood and the cuticle being the paint on the outside.

20. Morphology: Medulla
canal like structure of cells that runs through the center of the cortex

21. Medulla of Different Species make drawings and descriptions of the different species’ medullae

22. Medullary Index
Measure of the diameter of the medulla relative to the diameter of the hair shaft
Used to differentiate between species
Usually expressed as a fraction
Humans: medullary index < 1/3
Animals: medullary index > 1/2

23. Forensic Analysis of Medulla
Presence of medulla varies quite a bit: even hair to hair
Human head hairs generally have no medulla or may be fragmented ones; except Mongoloid (Asian) race whose medulla is usually continuous
Most animals have medulla that is continuous or interrupted
The shape of the medulla can help identify a species
Examples:
Most animals and humans: cylindrical
Cats: pearl shape
Deer: spherical occupying whole hair shaft

24. Identification and Comparison of Hair
Morphology does not allow identification of individual
Medullary index, and medullary shape are most often used for hair comparison
11 percent of all morphological hair matches are generally found to be non-matches — hair that is identified as being ‘similar’has been found to actually not be the same person — must be confirmed by DNA comparisons

25. Can the racial origin of hair be determined?
Old terms: Caucasian (European), Negroid (African), Mongoloid (Mongoloid)
Mongoloid has continuous medullae
Caucasian has even distribution of pigment in cortex
Negroid has unevenly distributed pigment.

26. Caucasian hair
Caucasoid (European) Hairs of Caucasoid or Caucasian origin can be of fine to medium coarseness, are generally straight or wavy in appearance, and exhibit colors ranging from blonde to brown to black. The hair shafts of Caucasian hairs vary from round to oval in cross section and have fine to medium-sized, evenly distributed pigment granules.

27. Mongoloid hair
Mongoloid (Asian) Hairs of Mongoloid or Asian origin are regularly coarse, straight, and circular in cross section, with a wider diameter than the hairs of the other racial groups. The outer layer of the hair, the cuticle, is usually significantly thicker than the cuticle of Negroid and Caucasian hairs, and the medulla, or central canal, is continuous and wide. The hair shaft, or cortex, of Mongoloid hair contains pigment granules that are generally larger in size than the pigment granules of Caucasian hairs and which often appear to be grouped in patchy areas within the shaft. Mongoloid hair can have a characteristic reddish appearance as a product of its pigment.

28. Negroid hair
Negroid (African) Hairs of Negroid or African origin are regularly curly or kinky, have a flattened cross section, and can appear curly, wavy, or coiled. Negroid pigment granules are larger than those found in Mongoloid and Caucasian hair and are grouped in clumps of different sizes and shapes. The density of the pigment in the hair shaft may be so great as to make the hair opaque. A Negroid hair shaft exhibits variation or apparent variation in diameter because of its flattened nature and the manner in which it lies on the microscope slide. Twisting of the hair shaft, known as buckling, can be present, and the hair shaft frequently splits along the length.

29. Hair Evidence Review
Hair is one of the most common forms of trace evidence, but is not the best type of physical evidence for establishing identity. It is not possible to show with any certainty that two hairs came from the same person or animal.
However, hair can be used to rule out certain suspects or scenarios. It can also be used to corroborate (support) other physical evidence if it is consistent with the rest of the evidence.

30. A strand of hair has three distinctive parts: cuticle, cortex, and medulla. By examining these parts as well as pigmentation and other features an investigator can compare hair samples from a crime scene.
Hair can be used for DNA testing.
The hair follicle, which is in the base of hair, contains live cells with DNA material and must be present for DNA testing.
For using it in analysis of DNA (paternity tests, crime investigations, etc), the hair must be uprooted. Pulling out hair is easy (we lose malt hair everyday) but to pull out the root as well, that hurts.
The hair which falls as breakage isn't useful for DNA testing since it doesn’t have a root.

31. Fibre Evidence
A fibre is the smallest unit of a textile material that has a length many times greater than its diameter.
Fibres can occur naturally as plant and animal fibres, but they can also be man-made. A fibre can be spun with other fibres to form a yarn that can be woven or knitted to form a fabric.
The type and length of fibre used, the type of spinning method, and the type of fabric construction all affect the transfer of fibres and the significance of fibre associations. This becomes very important when there is a possibility of fibre transfer between a suspect and a victim during the commission of a crime.

32. Matching dyed synthetic fibres or dyed natural fibres on the clothing of a victim to fibres on a suspect’s clothing can be very helpful to an investigation, whereas the matching of common fibres such as white cotton or blue denim cotton would be less helpful.
The discovery of cross transfers and multiple fibre transfers between the suspect's clothing and the victim's clothing dramatically increases the likelihood that these two individuals had physical contact.

33. Many different natural fibres originating from plants and animals are used in the production of fabric.
Cotton fibres are the plant fibres most commonly used in textile materials
The animal fibre most frequently used in the production of textile materials is wool, and the most common wool fibres originate from sheep.

34. Cross-section of a man-made fibre
More than half of all fibres used in the production of textile materials are man-made. Some man-made fibres originate from natural materials such as cotton or wood; others originate from synthetic materials.
Cross-section of a man-made fibre