Biological study and forensic examination of hair and fiber.

1. HAIRS AND FIBERS
• PRESENTED BY: YASHASHVI LAD
• M.SC FORENSIC SCIENCE

2. INTRODUCTION OF HAIR
Definition:
• hair is a filamentous biomaterial that
grows from follicles found in the dermis.
• Hair have a structure consisting of several
layers:-
• A) Cuticle
• B)Cortex
• C)Medulla

3. HAIR MORPHOLOGY

4. • Hair is produced from a structure called the
hair follicle. Humans develop hair follicles
during fetal development, and no new follicles
are produced after birth.

5. HAIR STRUCTURE

6. CUTICLE
• Cuticle is the outer layer of
hair shaft.
• It consist of several layers of
flat, thin cells without over-
lapping one another.

7. CORTEX
• The region of hair located
between cuticle and
medulla layer content
pigment granules known as
cortex

8. MEDULLA
• It is the central part of the hair , made up of
large loosely connected cells which contains
keratin.
• Some times medulla may be absent in some
species .
• On the basis of appearance of medulla it is
divided into 5types:-
• 1) CONTINUOUS
• 2) INTERRUPTED
• 3) FRAGMENTED
• 4) SOLID
• 5) ABSENT

10. TREATED HAIR
Forensic investigators sometimes can link hair
from a location with an individual.
– Bleaching disturbs the scales on the cuticle and
removes pigment leaving hair brittle and a yellowish
color.
– Dyeing colors the cuticle and the cortex of the hair
shaft.
Because of this and because hair grows daily, a
person’s treated hairs will have specific char-
acteristics in common with her or his lost
hairs.

11. DIFFERENCES BETWEEN HUMAN &
ANIMAL HAIR
FEATURE HUMAN HAIR ANIMAL HAIR
CORTEX The width of cortex grater
than medulla
Usually less than the width
of medulla
DISTRIBUTION OF
PIGMENT
Towards cuticle Central or denser towards
medulla
MEDULLA Medulla discontinuous Medulla continuous
SCALES Imbricate Coronal, ring form

12. Using Hair in forensic investigation
• RACIAL DIFFERENCE:
• Hair examiners have identified some physical
characteristics that generally can be
associated with broad, racial groups.
• These characteristics, however, will not apply
to all individuals in these groups.

13. Racial Differences in Human Hair
RACE APPEREANCE PIGMENT
GRANULES
CROSS SECTION OTHERS
EUROPEN Generally straight
or wavy
Small and
evenly
distributed
Oval or round of
moderate
diameter with
minimal variations
Colour may be
blond, red
,brown or black
ASIAN straight Densely
distributed
Round with large
diameter
Shaft tend to
be straight
thick cuticle
continuous
medulla
AFRICAN Kinky curly or
coiled
Densely
distributed
clumped ,
may differ in
size and
Flattened with
moderate or small
diameter

14. USING HAIR IN FORENSIC
INVESTIGATION
• Macroscopic investigation can indicate length, color,
and curliness.
• Microscopic investigation can indicate fine detail in
hair structure.
– Phase contrast microscopy, for example, can
show the presence of dye or other treatments.
– Electron microscopes can provide more detail of
the surface or interior of the sample. In the
sample above, note the overlapping scales and
the pigment granules in the cortex.

15. COLLECTION OF HAIRS
• Hairs can be recovered from items using a
number of different techniques.
• Some of the methods used to collect hairs
from clothing and bedding items are scraping,
shaking, taping, and picking.
• Debris from large carpeted surfaces might be
vacuumed into a filtered canister.
• If the specific location of a hair on a clothing
item is important, it might be necessary to
pick off the hair or tape the item and record
where the hair was removed.

16. FIBERS

17. INTRODUCTION
• Fibers are a trace evidence.
• Direct Transfer: Transfer of fibers directly from
victim to suspect or suspect to victim. E.g.:
fiber from woollen sweater of victim >
attacker
• Secondary Transfer: Fibers are transferred
from the original source to a suspect and then
to a victim. E.g.: carpet fiber > victim >attacker

18. Classification of fiber
FIBERS
ANIMALS
PLANTS
MAN MADE
NATURAL
SYNTHETIC

19. NATURAL FIBERS
Plant fibers:
• Cotton from seedpods is the plant fiber most
commonly used in textiles (shown above).
• Coir from coconuts is durable.
• Hemp, jute, and flax from stems grow in
bundles.
• Manila and sisal from leaves deteriorate
more quickly

20. Animal fibers (made of proteins):
• Wool from sheep, cashmere and mohair
from goats, angora from rabbits, and hair
from alpacas, llamas, and camels are
commonly used in textiles.
• Shimmering silk from caterpillar cocoons is
longer and not as easily shed.

21. SYNTHETC FIBERS
• Half the products produced today are
artificially produced.
• Artificially produced fibers include rayon,
acetate, nylon, acrylics, and polyesters
• Rayon is the most common of this type of
fiber. It can imitate natural fibers, but it is
stronger

22. nylon
Examples of synthetic polymer fibers:
• Polyester—found in “polar fleece,” wrinkle-
resistant, and not easily broken down by light or
concentrated acid; added to natural fibers for
strength.
• Nylon—easily broken down by light and
concentrated acid; otherwise similar to polyester.
• Acrylic—inexpensive, tends to “ball” easily, and
used as an artificial wool or fur.
• Olefins—high performance, quick drying, and
resistant to wear.

23. COMPERISION OF NATURAL AND SYNTHETIC FIBERS

24. FORENSIC SIGNIFICANCE OF FIBER
• Fibers often fall off and are picked up during
normal activities.
• Very small fibers easily shed from most
textiles and can become trace evidence.
• In an investigation, collection of fibers within
24 hours is critical.
• Fiber evaluation can show such things as the
type of fiber, its color, the possibility of
violence, location of suspects, and point of
origin.

25. SAMPALING AND TESTING
• Weaving spun fibers (yarns) together produces
clothing and many textiles.
• Shedding from an article of clothing or a textile
is the most common form of fiber transfer.
• Natural fibers require only an ordinary
microscope to find characteristic shapes and
markings.
• Infrared spectroscopy can reveal something of
the chemical structure of other fibers that,
otherwise, may look very much alike.