Forensics of hair analysis

Analysis of hair and fiber , differentiating it between human and animals. analysis in identification cases of male and female and different places of body origin. Examination in sexual assault cases and extraction of DNA from hair from DNA fingerprinting.

1. EXAMMINATION OF HAIR
By
Dr. Kaleem khan

2. Hair is a filamentous biomaterial, that grows from
follicles found in the dermis.
Hair often refers to two distinct structures:
The hair follicle
The shaft

4. Hair grows from the papilla
Point of generation is made up of dead, cornified
cells
It consists of
◦Shaft that projects above the skin
◦Root that is imbedded in the skin

5. A cross section of the hair shaft may be divided
roughly into three zones.
The cuticle
◦(several layers of flat, thin cells laid out overlapping one another
as roof shingles, )
The cortex
◦(keratin bundles in cell structures that remain roughly rod-like)
The medulla,
◦(area at the fiber's center.)

8. Hair is composed keratin, rope-like intermediate filaments.
Hair growth begins inside the hair follicle.
 The hair that is visible is the hair shaft is considered "dead".
Other structures of the hair follicle include the
Oil producing sebaceous gland.
The erector pili muscles,

9. All natural hair colors are the result of two types of hair
pigment.
◦Eumelanin -dark-blond, brown, and black hair
◦pheomelanin - red hair.
Blond hair is the result of having little pigmentation in the
hair strand.
Gray hair occurs when melanin decreases or
disappears.

10. In humans, hair undergoes cyclical phases
Growth (anagen),
Transition (catagen),
Resting (telogen),
Anagen phase lasts about 1,000 days.
Telogen phase, follicle are dormant and hairs fall out- 100 days.
10 and 18% of all the hairs are in the telogen phase;
2% are in the catagen phase.
80 and 90% are actively growing.
There is no pattern to determine which hairs on the head are in
any phase at a given time

11. 
The cuticle is a translucent
outer layer of the hair shaft
consisting of scales that
cover the shaft.
Cuticular scales always
point from the proximal or
root end of the hair to the
distal or tip end of the hair.

12. There are three basic
scale structures that
make up the cuticle—
◦Coronal (crown-like),
◦Spinous (petal-like),
◦Imbricate (flattened).
Combinations and
variations of these
types are possible.

13. The imbricate or
flattened scales type
consists of overlapping
scales with narrow
margins.
 They are commonly
found in human hairs
and many animal hairs.

14. The medulla is a
central core of cells
that may be present
in the hair.
Human
Animal
Deer

15. The medulla, in human hairs, less than one-third the
overall diameter of the hair shaft.
The medulla in animal hairs is normally
Continuous and structured and
Greater than one-third the overall diameter

16. Measure of the diameter of the medulla relative to
the diameter of the hair shaft
Usually expressed as a fraction
◦Humans: medullary index < 1/3
◦Animals: medullary index > 1/2

18. Color
◦Human consistent in color and pigmentation throughout the
length of the hair shaft, whereas
◦animal hairs may exhibit radical color changes in a short distance,
called banding.
Pigmentation
◦human hairs is evenly distributed, or slightly more dense toward
the cuticle,
◦animal hairs is more centrally distributed, although more dense
toward the medulla.

19. Hairs found on a knife or club may support a murder and/or assault
weapon claim.
Human hairs can be classified by racial origin such as
◦Caucasian (European origin),
◦African-American (African origin), and Mongoloid(Asian origin).
◦The region of the body where a hair originated
◦The length and color can be determined.
 It can also be determined whether the hair was
◦Forcibly removed,
◦Damaged by burning or crushing,
◦Artificially treated by dyeing or bleaching.

20. Some of the methods used to collect hairs from clothing
and bedding items are
◦scraping,
◦shaking,
◦taping, and
◦picking.
 If the specific location of a hair on a clothing item is important,

21. Head hairs and pubic hairs exhibit a greater range
of microscopic characteristics than other human
hairs; therefore, head and pubic hairs are routinely
forensically compared.
Twenty-five randomly selected head hairs
same number of hairs be collected from the pubic

22. Caucasian
African-
American

Mongoloid

23. Certain features of
individual hairs
identify the region
of the body where it
originated.
Pubic Hair

24. Limb

25. Beard

26. Underarm hair
Chest hair
Eyebrow
General body hair

27. ◦Hair spray
◦Hair gel
◦Permanents
◦Hair cosmetics

28. Environmental/chemical damage
Mechanical damage
Crushed
Burned
Glass cut
Broken
Frayed
Twisted
Tangled

29.  Glass-Cut or
Broken Hair Tip
Cut Hair Tip
Worn Razor-Cut
Tip

31. Scissor Cut
Razor Cut
Broken Hair
Burned Hair

32. LICE

33. Often it is not possible to extract DNA fully, or there is
not enough tissue present to conduct an examination.
Hairs with large roots and tissue are promising sources of
nuclear DNA.

However, DNA examinations destroy hairs, eliminating
the possibility of further microscopic examination.

34. DNA from cells associated with the root can be extracted
and used for DNA analysis.
 Analysis of the DNA in the nucleus of the cell can be
used for determining identity and DNA from the y-
chromosome focuses on questions of paternity.
Mitochondrial DNA is useful for establishing maternity.
Roots of hair in the anogen (growth) phase contain more
DNA than hairs from the telogen (resting) phase.


35. contamination issues are important as dead skin cells,
which are also shed passively, contain DNA and may be
collected from surfaces along with hair.
If a hair from the telogen phase is collected, it may not
contain enough nuclear DNA for analysis, but it might
contain mitochondrial DNA.
If the hair has been forcibly removed, then pieces of
tissue may be attached and DNA analyses can usually be
run easily on these tissue cells.

36. DNA analyses are destructive techniques and consume
portions of the hair.
A full and detailed microscopical comparison with
possible known sources of hair should be done prior to
DNA analysis because it cannot always be done
afterwards.

37. THANKS