Hair Evidence
evidence, its presence on a crime scene link a suspect/criminal to crime scene or to a
victim and also victim to crime scene and criminal. Hairs present on humans body
on the head, arms, legs, pubic region and on other body areas. Each region of the body
has hairs with different characteristics attributable to that region and determines their
origin. Head and pubic area are the regions of the human body that’s mostly used in
forensic analysis. Hairs are the fine threadlike strands composed of protein keratin,
growing from the skin of humans, mammals and animals and formed from a structure
called the hair follicle. Hair follicles develop during fetal development. Hair length,
color, shape, root appearance, and internal microscopic features distinguish it from
one animal to another. The phase of growth of the hair (cyclical growth - anagen)
/(resting phase - telogen) are visible microscopic characteristics and easily determined.
Genes also plays a role in hair shape (round or oval) and texture (curly or straight).
Animal’s hairs comprise outer hairs or guard hairs, fur hairs, whiskers, and other
hairs from tail and mane
of an animal.
Microscopic hair -
Hair structure consist several layers:-
A) Cuticle
B) Cortex
C) Medulla
HAIR IN FORENSIC INVESTIGATION –
Length, color, and curliness of hair determine during macroscopic
investigation. It also indicates fine detail in hair structure.
Presence of dye or other treatments find out in Phase
contrast microscopy.
Detail of the surface or interior of the sample find out by
using Electron microscopes.
The race of an assailant or the region of the body from
where the hair was lost determined by the hair evidence. Hair can also provide
DNA evidence if the follicle (root) of the hair is intact. Hair evidence is called Individualized evidence when follicle is attached and consider as class evidence when hair follicle is not attached. The analyst gives
following information to the investigator –
Things that determined by hair evidence -
The specimen is of any Human or animal origin.
Race of the specimen hair (European, Asian, African).
Origin and color, shape and chemical composition of the
hair.
Manner in which hair was removed.
Treated hair and Drugs ingested (presence of toxins, dyes
and hair treatments).
Provide DNA details.
Age -
Cannot be determined definitively, however, the microscopic
appearance of definite human hairs, such as of children and elderly
individuals, provide a general sign of age.
ASSAULT AND HOMICIDE - These types of crimes involve hairs
interchange between victim and suspect.
RAPE - Cross transfer of fibres and hairs between clothing
of suspect and victim or on articles such as blankets or automobile seat covers.
BURGLARY – Possibility of hair evidence if head covering was
not used.
HIT-AND-RUN CASE - Forceful interaction between victim and
automobile, hair and fibers can generally be Found, stick to the grill, fenders,
door handles, or parts of the undercarriage.
In many other cases hair evidence is so valuable as in the
above cases.
Collection of hair evidence -
Hair and fibre are collected mainly at the scene of crime
and at the autopsy stage. Hairs can be collected by using a number of different
techniques -
Hair samples are collected from the surrounding area for the
purposes of eliminating peoples from police inquiries as well as to narrow down
the list of suspects. Collection of these samples through meticulous and
painstaking processes, which are carried out by Expert who themselves dressed
in protective cloths so that their hairs do not contaminate any evidence which
may pre-exist.
Scraping, shaking, taping, and picking are methods used to
collect hairs from bedding and clothing items.
Vacuuming should be done on large carpeted surfaces to
collect the samples into a filtered canister.
Samples should be collected in varying vials, tubes and grip
seal bags. It helps to stop the cross contamination.
Victim’s clothing should be examined for trace elements and also
checked for hairs that do not match with the victim. You can at this point also
collect animal hair.
The next stage of hair collection is at the autopsy, where
pathologist will scrape the underside of the victim’s fingernails for any hair,
skin material that might be there. Materials collected and stored in the same
manner for examination and comparison at a later stage.
Samples collected are sent to the laboratory (with control
samples from suspected person). Control samples recovered from all parts of the
head and from pubic area. Prior to sample collection the area should be combed
for foreign hairs.
Hair samples should be collected using tweezers.
Hair evidence should be picking up with gloves fingers or
tongs and then wrapped in a fold paper and then place into an envelope, labeled
as usual.
Hairs combined with blood or any other fluids should be
collected and preserved intact whenever possible. Use the protocols for fluids preservation.
What is Hair Microscopy?
Hair can be analyzed and tested by microscopic comparison
and chemical analysis by comparing the suspect's hair with hair found at the
crime scene or recovered during autopsy. Microscopic comparison found out the
color, texture, shape and other visual aspects of the sample, while chemical
analysis specifies the presence of drugs, toxins, dyes and other chemicals.
Hairs found at scene of crime also matched to the person who
left it there by using modern DNA techniques.
Hair examination process has different steps; first one is
to found out whether the hair in question originated from a human being or an
animal.
Comparison microscope contains two compound light
microscopes joined by an optical bridge that allows the viewing of known hairs
and questioned hairs. We can put a glass microscope slide containing known hair
position on the stage of one microscope, and a glass microscope slide containing
a questioned hair position on the stage of the other microscope. It helps the
hair examiner to match the microscopic characteristics of the known sample and
questioned sample in one field. Approximate range of magnification used is 40X
to 400X.
In the first step if the hair examiner fount that hair is originated
from an animal, then it will further identify with a particular type of animal
or its species.
Many factors impact the reliability of a hair association,
including the training, experience, suitability of known hair standards, and capability
of equipment, method of evidence collection, evidence processing techniques
employed and methodology of the hair examination process.
Significance of Hair Evidence
Hair transfer occurred due to physical contact, when hairs
transfer directly from the region of the body where they are growing, it is a
primary transfer. When they can transfer from the clothing of any person, it is
a secondary transfer. Hairs shed on the cloths and on items in the
surroundings. Forcibly removed hairs suggest a violent confrontation.
The transfer of hair and its discovery as trace evidence and
its presence linking a suspect to a victim or a suspect/victim to a crime scene.
The types of hair recovered, how hairs can be transferred, the condition and
number of hairs found and other factors which affect the significance of a hair
match are significant concerns of crime scene investigators, hair examiners and
prosecutors. Microscopic comparison of questioned hairs characteristics to
known hair samples help in determining whether a transfer may have occurred.
Case situations that affect the significance of identifying
hairs –
The location, number, and condition (forcibly pulled or
burnt, for example) of recovered hairs is very important, when a family member
involved in a crime.
In hair examination the involvement of the victim’s companions,
coworkers, and other persons who have logical contact or access to the victim
and/or to the scene of crime is an additional consideration.
When hair associations have been made consider the
situations involving strangers; it’s a great significance to the case.
MR. DEEPAK PAWAR has been working as Finger Print Expert / Police Officer in Finger Print Bureau , Delhi Police at New Delhi since 2001 . He is the senior most Finger Print Expert , attending / visited several scene of crime and solved many crime cases .He has passed M.Sc (Chemistry) and he is the Member of International Association of Identification . He is the Member of Delhi Police welfare association . He is supervising the Forensic , New Delhi District , Mobile Crime Team . He is one of the Expert in the Special Investigation Team held for investigation of important cases . He has been giving fingerprint proficient training to Delhi Police personnel's . He has been Presented / giving lectures on topics related to forensic science . He is also making examination paper of Finger Print proficient course . He is awarded with Police Medal by MHA and Delhi Police.