Table of Contents
Notes By-
Sachin Gupta
Cleared UPSC 2017 with AIR-3
1.1 INTRODUCTION
Forensic anthropology may be defined as that branch of physical anthropology which for forensic purposes deals with the identification of more or less skeletonised remains known to be, or suspected of being human. The identification process provides opinion on the age, sex, ethnic group, stature and other characteristic of the individual who is excavated, which may lead to his or her recognition. In case of dead, generally scenario is having a skeleton in full or just remains. From these examples, one can classify the issue of identity into three
classes as, 1) criminal cases where unidentified body/skeleton/skeletal remain
etc. is found,
2) cases of identification of dead in mass disaster, man-made or
natural, to settle their religious, inheritance, compensation, insurance issues and
3) where mass graves are discovered in war and genocide cases.
1.2 SCOPE
Whether living or dead, the ultimate goal of examination is personal identification
as identification is a must requirement for a person. A person may be identified
through many traits of permanent and transitory nature like physical appearance,
gait, facial features, scar marks, tattoo marks, moles, birth marks, occupational
marks, (congenital) abnormalities, somatometric, osteometric and craniometric
dimensions. In this unit, we may restrict ourselves to the use of the knowledge of
physical anthropology to identify the skeletal remains as all the aforementioned
features may lead to positive identification. Whenever skeletal remains are found
the forensic anthropologists on examining them try to answer the following key
questions:
a) Whether the bones are human or non-human?
b) Whether they belong to one or more than one individuals?
c) What would be the probable sex?
d) What is the probable age of the individual?
e) What is the ethnic group/race of the individual?
f) What would be the approximate height of the individual?
g) What are the other characteristic features that can lead to his/her
identification?
1.2.1 Indian Scenario
In India, forensic anthropology related case work was undertaken by forensic
pathologist till a few decades back and there was no provision to recruit forensic
anthropologist in forensic science laboratories. But now all forensic laboratories
have a Forensic Anthropology Unit under Biology Division where examination
of skeletal material is performed. In developed countries like USA unlike India,
forensic science laboratories have forensic anthropologist to tackle the cases
related with skeletal remains and many universities run courses related to it.
There are organisations like American Board of Forensic Anthropologists (ABFA)
which look after the overall performance of all its members and update the subject
with new findings. It regulates the conduct of its entire members.
1.2.2 Visit to the Scene of Occurrence Forensic Anthropology
When a crime scene is to be visited where an unidentified body or skeletal remains
are reported to be present, a team is constituted by the concerned police station,
under the supervision of an Investigating Officer (I.O.), where the crime is reported
and sent to the crime scene to examine. This team conducts the search for the
physical evidence, identifies them, pack them and prepare an inventory of all the
items after photographing the crime scene from different angles. A sketch of the
crime scene is also prepared and then the team returns back to the police station.
All the exhibits are labeled and numbered and sent to the forensic laboratory for
examination. In the forensic laboratory the exhibits are forwarded to the concerned
divisions for examination. For example the skeletal material, if recovered, is
sent to the Forensic Anthropology Unit of the Biology Division.
1.2.3 Whether the Bones are Human or Non-Human?
A careful examination of the skeletal material recovered a forensic anthropologist
can differentiate a human bone from that of a non-human with the help of
comparative anatomy knowledge. There are obvious variations in the skull of a
human and a non-human as the animals have a large facial part in comparison to
the cranial part. This is just the reverse in case of human who possess a very
large cranium and a very small facial component. Secondly the position of foramen
magnum is medial in case of human while among animals it is posteriorly located.
The eye orbits are anteriorly located for humans while among non-humans they
are laterally placed. The human long bones exhibit torsion while the non-human
bones do not exhibit any kind of torsion. Even if the bones are burnt, the charring
is never complete and if examined with care, it is possible to recognise the material
as bone. Problem is faced when many synthetic materials due to high temperature
burning may take a typical shape looking like bone or part of bone or when very
small fragments are found. In such cases if the fragment is head or condyles of
bone still it is safer to say about its identity but when it is not so then microscopic
study of the bone may lead to ascertain about it through the presence of Haversian
canal system.
1.2.4 Whether they Belong to One or More than One Individual?
On examining the skeletal remains it is quite simple to identify if the remains
belong to one or more than one person. The simplest way is the sorting technique
where we sort out similar looking bones. For example if there are five femora
and three radii and two fibulae ,they could belong to a maximum of five persons
provided that all the five femora exhibit different length and belong to same side
(right or left) similarly the three radii could be of three persons or two persons
depending upon their side . The two fibulae could be of one person or two persons.
While deciding this, the expert must know to conduct measurements on the bones
as well as identify their sides.
1.2.5 What is the Probable Sex of the Individual?
Determination of skeletal sex is of prime significance as it helps in the process
of identification. It can be performed by conducting a detailed examination of
skull and pelvis with a reasonable accuracy.
The examination of skull involves non-metric observations on the texture of the
skull, its weight, condition of the supra-orbital ridges, projection of frontal and
Advanced Areas in Practicing Anthropology parietal eminences, shape of the orbits, margins of the orbits, size of mastoid processes shape of foramen magnum, shape of palate, size of lower jaw, slope of the forehead, and shape of palate. A careful examination of these traits can help
in assessing sex of an unknown skull up to around 90 percent accuracy.
Similarly the following observations on the pelvis can help in determining the
skeletal sex from pelvis:
We observe the size and shape of the pelvis to begin. Subsequently the variation
in the size of acetabulum and obturator foramen is observed. The wide greater
sciatic notch and obtuse sub-pubic angle is a typical female character. Variation
in the size of auricular surface, ischio-pubic ramus and alignment of Ilium bone
and size and shape of the sacrum is observed to determine the sex of the pelvis
with around 93 percent accuracy. On combining the skull and the pelvis the sex
determination can be performed with ober 96 percent accuracy. The long bones
alone do not help much in sex determination but in combination with the skull
and pelvis they prove useful.
1.2.6 Identification of Bones
To identify the bones one has to have the knowledge about Human Osteology.
The human body has a fixed number of bones and they may be classified as flat
bones (cranial bones, in-nominates and scapula), long bones (bones of upper
and lower limbs), short bones (metacarpals, metatarsals and phalanges of hand
and feet) and irregular bones (vertebrae, carpal and tarsal bones). Complete bones
are not difficult to identify due to their typical features but when they are
fragmentary, it depends upon the part of the bone available for examination.
Activity 1
Visit any anthropology department, or a medical college to get familiar
with bones and identify each bone of the human skeleton.
1.2.7 Racial Affiliation of the Person from the Remains
The population of the world may be divided into three major groups i.e.,
Caucasoid, Mongoloids and Negroids on the basis of their morphological features,
geographical area of inhabitation added to their differentiation, but due to
migration and interbreeding the concept of race does not hold good any more.
However the forensic anthropologist may attempt to determine the race of the
skeletal remains on the basis of skull.
The features like head shape, breadth of nasal aperture, nasal root, jaw thickness,
brow ridge size and forehead slope help in categorisation. There are certain indices
based on craniometric measurements which may help in categorising skulls into
different racial categories.
1.2.8 What is the Probable Age of the Individual?
Human skeleton provides a good number of indicators of age and sex and both
can be determined to a very high degree of correctness depending upon which
part of the skeleton is available for examination. For age determination, bone
histology (number of osteon increases with age),teeth eruption sequence, cranial
suture closer, pubis symphysis face, sternal end of ribs and ossification of various
bones help to a large extent.
There are two set of teeth in the whole life of a person that is milk teeth and Forensic Anthropology
permanent teeth. Formation and growth of teeth may also help in estimation of
age of an individual of younger age. Demerijan suggested an eight stage formula
of teeth development for age determination. Another parameter, which can be
used for age determination, is from changes in teeth because of advancing age.
Gustafson developed a method to determine the age beyond 11 years by studying
the degenerating stages of teeth like attrition (wearing down of incisal or occlusal
surfaces), periodontosis, development of secondary dentine, cementum
apposition, root resorption and transparency of root (four stages of changes in
ascending order).
Cranial sutures can be said as the broadest indicator of age but when no other
body part except skull is available, these can also give an estimate of age. Many
works have detailed closure pattern of each suture including age at the time of
fusion of various parts of a particular suture. It has been observed that suture
closure in different populations varies significantly. The major cranial suture
which are used in age estimation are as following, (metopic suture, basilar suture,
sagittal suture, sagittal suture, lambdoid suture, parieto-mastoid,temporomastoid,
occipito-mastoid,spheno-temporal and spheno parietal). The beginning
of the closure and the complete closure of these sutures provide an estimate of
the age of an individual.
The face of pubic symphysis provides a more reliable parameter than suture
closure and it can be studied for the changes on this surface with age by dividing
the whole process into 10 stages. For these stages, outline of the face having
outer border, inner border, a superior and inferior extremity is studied. Also,
some features found on the surface like ridging, billowing and ossific nodules
are observed to determine a particular stage and thus inferring from it the age.
Age may also be estimated by examining sternal end of the ribs with respect to
changes in the form, shape, texture and overall quality of the rib. In addition to
this, some changes like formation of the pit on the medial articular surface also
indicate age.
Ossification of bones indicates the phases of growth in the bone which are age
dependent. If we take the example of long bones, which are considered to be
most suitable for age determination from the ossification, in the initial stages, it
has only diaphyses and the epiphysis. With the advancing age they grow and
meet with each other and then epiphyseal plate is formed. It lengthens to unite
with epiphysis. When the union is completed then bone stops growing and only
a line called epiphyseal line is visible at the joining place. Most of the bones get
ossified by the age 18. Thus the age estimation from this parameter has this
limitation. The process of ossification can be observed in living through
radiographic techniques like X-rays and CT scan.
Activity 2
You may buy an artificial skull from the market and try to identify the
bones. Also you may see the teeth and try to estimate the age from the type
and number of teeth.
Advanced Areas in Practicing Anthropology
1.2.9 What would be the Approximate Height of the Individual?
The answer to this question is based upon the fact that body parts have a definite
relationship with the body height. Forensic anthropologists have tried almost
every bone of the body to determine the stature but long bones especially of the
lower extremity prove to be more reliable indicator of stature estimation. The
methods are based upon derivations of ratios of the bones with total body height.
These may be represented in the form of multiplication factors and regression
equations. These methods are both population and sex specific, therefore they
must be used with utmost care. When a complete bone is present then it is
measured and multiplied with the multiplication factor of that particular bone or
its value is put in a regression equation (univariate or multivariate) and stature is
estimated but when bone is in the form of fragment then first attempt is made to
estimate the total length of the bone and then from that value stature is estimated.
But in such cases definitely reliability of estimate is reduced to a large extent.
Regression formulae and the multiplication are both population and sex specific.
Therefore they must be used very carefully after ascertaining the sex and the
ethnic group where ever possible.
1.2.10 What are the other Characteristic Features that can Lead to His/Her Identification?
This is most difficult to conduct. Most of the time, depending upon what part of
the skeleton is found, we may succeed in narrowing down our search for the
individual but it is really difficult on the basis of anthropological methods only
to individualise the skeleton. As the identification process is based upon the fact
that identity of an object will be more precise if the same is having some special
and rarer type of the characteristic. Congenital anomaly of any type in the bones,
fractured bones when healed may develop some deformity, dental treatment as
some filling, surgical implants in the bones as nail, screw, etc. are good indicators
of individualisation.
When skull is available for examination it can be used for personal identification
with more than one method. Skull-photo superimposition technique is used when
photo of the suspect is available where as when only skull is there, facial
reconstruction method can be used to make approximate face of the person to
whom the skull may belong. Both the methods have been improved a lot with
the help of new technology available. While skull photo superimposition is now
done mostly with advanced technique called computer based video skull
superimposition, the facial reconstruction technique which involves direct
application of clay on the skull or the copy of skull, is done through 3D computer
based facial reconstruction. The reconstructed faces are flashed in the print and
electronic media so that someone may recognise the face and report to the
authorities concern.
Activity 3
You may ask your friend to volunteer and put his right foot on a white
paper. Draw the outline of the foot with the help of a black lead pencil on
paper. Measure the maximum length of the foot and multiply it with 6.5.
Now, measure the height by requesting him to stay against a wall. See, how
this value differs from the actual height of the volunteer.
Forensic Anthropology
1.3 BIOMETRICS
The human brain recognises objects including human beings due to cognitive
capabilities. Once brain makes an observation, it may remain for years in its
memory depending upon a large number of factors like frequency of same
observation, significance of the observation etc. The object is memorised on the
basis of a large number of features which are stored in the brain at the time of
observations. When the same object is encountered again, the brain recognises it
on the basis of stored information and comparing it with the observed information,
it can be repeated any number of times though each time some variation in the
process maybe there and some error may occur. Like for example, while in a
crowd we mistakenly address someone else as someone known to us or sometimes
twins are mistakenly identified. To correct such errors, the practice of Brtillonage
was created where measurements of various body parts were recorded of the
individual convicts so that they could be identified easily when they come again
as convicts. It was found by the French anthropologist/criminalist, Bertillon. He
pointed out that combination of these body measurements were unique and
therefore this practice continued till an erroneous identification of prisoner was
established. By that time, use of fingerprints in personal identification was
introduced and Brtillonage was combined with it. These examples may be said
as a precursor of the modern biometry though it was manual. All the collected
fingerprints were classified as per the formula; unknown fingerprints were
retrieved from the record if they are available already in the record.
With the advancement in technology, attempts were made to make the recognition
process easier, faster and error proof and thus came into existence biometry.
Biometrics can be defined as the science of verifying and establishing the identity
of an individual through physiological features or behavioral traits. The term
may be explained by its essential two dimensions that are the characteristics and
the process. Characteristic invariably must be biological (physiological and
anatomical) and /or behavioral while the process may involve a system leading
to identification based on the above mentioned characteristics. It can be said that
the characteristics are supposed to make a unique pattern that is memorised by
the machine and at the time of retrieval, it compares the pattern in question with
the stored pattern data and recognises one unique pattern matching the questioned
one. In modern technological terms it is known as pattern recognition, a branch
of artificial intelligence.
The first systematic biometrics based on iris pattern was proposed by
ophthalmologist Frank Burch in 1936 followed by face and speech based
biometric in 1960.
The fingerprint based biometric tools were developed by FBI in sixties and then
many more parameters were introduced as signature, palm and gait pattern.
After standardisation of all the processes of biometrics, first personal identification
system became operational in 2004 and is known as the United States Visitor
and Immigrant Status Indication Technology (US-VISIT). Presently, we can
classify all the biometric tools used in personal identification in three groups as
physical biometrics, behavioral biometrics and chemical/biological biometrics.
Advanced Areas in Practicing Anthropology
Physical biometrics is based on the physical features of the human body as face,
iris pattern, hand geometry and fingerprints. Example of behavioral biometrics
is handwriting, signature and speech while under chemical/biological biometrics,
perspiration; skin composition can be included though this group of biometrics
is still at the developmental stage.
Any biometric tool to be used as an efficient identification means, it has to have
the following five properties: 1) It should be universal i.e. trait must be present
in every one, 2) It should be unique that is trait should vary to that extent that it
is different in every member of relevant population, 3) The trait should be
permanent, 4) The trait must be measurable, 5) The trait cannot be imitated easily.
Apart from this, technology being involved in using any trait should be accurate,
fast and robust. Also the interface between the person and the machine should be
acceptable with respect to the ease and comfort. Privacy of the information may
also be included here for consideration of any technique.
Biometrics can be used for two purposes, one for verification and the other for
identification.
In case of verification, the questioned biometric is compared against the available
template of the biometric in stored data. This is generally used for access control
devices where only authorised person is allowed to have access to that device/
application. In case of identification, one or more comparisons are performed
and if the questioned data matches with the existing templates then the identity
is established.
These days, biometrics which are in use, are based on the following:
Fingerprints, Iris pattern, Face prints, DNA identification, Voice prints,
Handwriting analysis.
Some of the salient features of each of these biometric tools are explained below:
1.3.1 Fingerprints Biometrics
Inked fingerprints are obtained on paper and scanned or fingerprints are directly
scanned with the help of special scanners available commercially in the market.
The scanned fingerprint is then looked for ridge details (minutiae) like ridge
endings, ridge bifurcations with respect to their position and direction, number
of ridges between particular two points. In this way, for each fingerprint, a unique
template is developed and stored in the data base which is used for comparison
when a new fingerprint is received.
The fingerprint biometrics has many applications as criminal identification where
Automated Fingerprint Identification System (AFIS) is used to retrieve
fingerprints of criminals. Similarly, the unique identification (UID) or ADHAAR
has been started by the government of India to have a unique identification based
on the biometric tools including fingerprints.
1.3.2 Iris Patterns Biometrics
It is based on the concept that iris pattern is unique and permanent throughout
the life of the person since formed first in around 8th month of intra uterine life.
To capture the iris image a high resolution camera is used and the images are Forensic Anthropology
converted into a template called Iris codes. To capture the high quality images,
illumination is made with the help of near infra red radiation.
1.3.3 Retinal Pattern Biometrics
Retina present in the back of the eye is illuminated and blood capillaries pattern
in the area is photographed with the help of high resolution camera. The digitised
images are converted into templates and stored for further comparison when
required.
1.3.4 Facial Recognition Biometrics
The human face is the most commonly used parameter to identify a person by
others from his family, friends etc. One recognises near ones immediately in a
fraction of second by just looking. This very property of the face that it has a
combination of features like eye, eyebrows, nose, lips, chin etc., may provide a
unique template for each person. In biometrics, as the image of the face may be
available in dynamic for in videos therefore, in addition to static images of the
face, system for comparing dynamic images was required to be developed. The
face recognition biometrics helps in preventive forensics where surveillance of
the person having access to public places like airports, railway stations and malls
etc., can be maintained.
1.3.5 DNA Biometrics
DNA of every individual is unique with an exception to monozygotic twins and
therefore can prove as the most reliable and robust biometric tool for all biometric
purposes. Earlier the technology to analyse DNA was not very common and cost
effective therefore it was not possible to think of a viable model but now the
technology has become very simple and cost effective and the situation has
changed. Another reason for choosing this tool may be easy availability of DNA
from an individual. Almost everything belonging to a person like saliva on
envelope; blood; hair; finger nails; used tooth picks; ear buds; sweat etc may be
a very good source of it as every one of these has cells containing DNA. The
only drawback of this method is that it is too expensive and secondly no data
base is available for comparison.
1.3.6 Handwriting and Voice Biometrics
Handwriting of a mature person is said to be unique and for centuries being used
to establish the authorship of a document or signature on the basis of the unique
way of formation of writing strokes. But, in case of modern biometrics, it is not
the case and writing geometry is considered in static format of biometrics while
in dynamic handwriting biometrics along with geometry, dynamic features like
acceleration, velocity, pressure etc are used to recognise an individual. For this,
special writing platforms and pens are designed to record the features and convert
into templates.
Similarly voice has individuality, which is due to the shape and size of vocal
cord, mouth, nasal cavity and lips. Any variation in these may also result in
variation in the voice. To collect the specimen of the voice, text dependent or
text independent modules are available which help in collection of uniform sample
for comparison. It is frequently used in telephone conversation regarding password
setting, tele-banking etc.
Advanced Areas in Practicing Anthropology
Both these tools are behavioural biometrics based and therefore chances of higher
false rejection and false acceptance rate is observed. Both these systems have a
restricted applicability due to lack of data base. In fact voice recognition is case
dependent and can’t be used as a biometric tool.
By acquiring the knowledge of such new technologies, one can start one’s own
agency to acquire the data of employees for various industries, government
agencies, impart training and also become an employee at Adhaar (Unique
Identification Authority of India).
1.4 DERMATOGLYPHICS
A fingerprint is an impression of these friction ridges present on the fingers’
palm, toes and soles.
Role of fingerprints in personal identification
Personal identification through fingerprints has long been recognised and is
regarded as the greatest contribution to law enforcement. Though, not everyone
has been fingerprinted but huge data has been collected on fingerprints that could
be used safely for the absolute identity of an individual.
From these studies the following fact based principles have been evolved:
1) A fingerprint is an individual characteristic. No two fingers have identical
ridge characteristics. So far no two fingers have been observed to possess
identical ridge characteristics.
2) A fingerprint will remain unchanged during an individual’s lifetime as they
appear in intra-uterine life and remain till the time skin is damaged
permanently or disintegrated after death. Certain diseases also may cause
damage to the friction skin.
3) Fingerprints have general ridge patterns which make it possible
to systematically classify. This advantage allow us to classify fingerprints
of large number of individuals systematically just like books are classified
and arranged in the library to retrieve them easily to save time.
Use of fingerprints in personal identification is very common in the following
fields:
• Identification of criminals whose fingerprints are found at the scene of crime.
• Identification of fugitives through fingerprints comparison.
• Identification of persons and maintenance of identity records (service or
criminals).
• Identification of unknown deceased person.
• Identification of mass disaster victims.
• Prevention of hospital mistakes in exchange of newly born babies.
• Establishing correct identity in cases of kidnapping, unconscious persons,
missing persons, mistaken identity.
• Detection of bank forgeries and cases related with money and property where Forensic Anthropology
instead of signature, thumb impressions are marked.
• Authentication through biometrics in cases of entry in offices, hotel rooms,
access to computers or such gadgets.
• In passport and immigration cases.
With the introduction of Automated Fingerprint Identification System (AFIS)
technology, use of computers is possible for quick retrieval of recorded
fingerprints data. In most of the cases, chance fingerprints may be available at
the scene of occurrence which may be invisible to naked eyes and called latent
fingerprints. Therefore, it is required to make them visible for further analysis to
establish identity. For this, various physical and chemical methods are available.
1.4.1 Various Types of Fingerprint Pattern
The dermal ridges tend to make some specific patterns on distal phalanges of the
fingers represent following type of the patterns and are of immediate concern.
The main types of the patterns are as following: Arch; Loops; Whorls.
Apply a thin film of the printing ink on the distal phalange of the fingers and roll
it on a paper to get a rolled impression of the finger.
Activity 4
Get an ink stamp pad and touch ridges side of your thumb lightly to the ink
pad so that the ridged skin may be inked. Move this inked thumb on the
white sheet. Take a hand lens (magnifier) to see the magnified image of the
print and identify the pattern type. You may repeat the same process with
other fingers of both the hands.
1.4.2 Scene of Crime Fingerprints
Fingerprints found at the crime scene may be of three types: 1) Visible fingerprints,
2) Plastic fingerprints, and 3) Latent fingerprints.
Visible fingerprints as the term suggests, are visible by naked eyes without any
aid. The fingerprint is visible as long as there is sufficient contrast between the
print and its support. They do not require any treatment for their enhancement
and can be photographed directly for record and further analysis purpose
Plastic fingerprints are those prints which are formulated on soft, greasy or
plastic surfaces. These are visible and thus can be photographed and sent for
comparison purpose.
Latent fingerprint is the most common form of fingerprint evidence but they
have to be made visible. The application of an optical, physical or chemical
treatment is required to visualise it. The latent fingerprints are deposited by the
friction ridge surface and composed of complex mixture of natural secretions
and contaminants from the environment.
Development of fingerprints depends upon the type of surface on which they
exist, temperature of the surface, and surface texture. All surfaces bearing latent
fingerprints can be divided into three main groups: 1) porous (e.g., paper),
Advanced Areas in Practicing Anthropology
2) semi porous (e.g., polymer bank note), and 3) nonporous (e.g., polythene).
Different type of the surfaces may need different set of treatment therefore it
should be kept in mind that same type of surface should be tried to evaluate a
proposed detection sequence before proceeding for the same treatment on the
evidence material.
1.4.3 Development of Latent Fingerprints
Large number methods are available to develop the latent fingerprints. By
acquiring the knowledge of fingerprints, one can become a fingerprint expert
giving opinion about the identification of the disputed fingerprints in cases of
land and property disputes. One can also work as free lancing fingerprint recorder
for the immigration agencies of various countries who require fingerprints of the
applicant.
Activity 5
Take a white paper or a white laminate sheet; impress your palm on the
surface. Put some colour powder as Holi colour (Gulal), Turmeric powder
or any such colour powder on one corner of the surface and roll the paper
slightly up and down. Observe, if the ridges are visible. If so, then latent
fingerprints are developed.
1.5 EXAMINATION OF BODY FLUIDS AND
TISSUES
Tissue material, blood and other body fluids may be encountered in most of the
crime related as well as other cases as mass disasters, accidents. Blood and
damaged, disintegrated body parts are generally found in such cases. In addition
to this semen, saliva, urine, vomit etc. may also be available in many cases of
offence. These may be found in stained form therefore a little different
methodology is to be adopted in such cases. First, is to examine the stain physically
by naked eyes or with special radiations depending upon the situation. After
successfully locating the stains they must be encircled so that in laboratory they
can be examined without wasting time to relocate. To ascertain whether the
stain is blood or some other red coloured material we have to go for presumptive
tests like Benzedrine test, Phenolphthalein test. Once it is confirmed that it is
blood then the question arises whether the blood is human or not? For this
precipitin test is conducted where suspect blood extract is taken in a special tube
called precipitin tube and to this different antisera like anti human sera, anti cow
sera, anti dog sera, anti fowl sera may be added. It is important to ascertain this
fact, as many times fake cases are made where animal blood is used. After this,
to find out to whom this blood belongs and this is called individualisation. If the
blood found at the scene is found to be of B group and none of the suspects
belonged to this group then it could be safely said that the blood from the scene
belongs to none of them. From the fresh blood it is not an issue to determine the
blood group in no time as antisera are available which reacts with their
corresponding antigen present in the blood but in case of stains where it may be
not only old but also may have been disintegrated. In this case, blood groups are
determined indirectly by techniques like, absorption-inhibition technique,
absorption-elution technique and mixed agglutination technique. The same
techniques are applied to determine the blood groups from other body fluids and Forensic Anthropology tissue material. The stains other than blood as of saliva, semen urine are generally found on the garments and therefore may not be visible clearly by naked eyes.
Therefore the garments suspected of having these stains are examined in ultra
violet radiation to locate them. After location, the same may be extracted for
their identification. Semen stain may be identified by acid phosphotase test, a
test for semen specific protein P-30 and finally the microscopic examination of
stain for the presence of spermatozoa. The presence of saliva may be confirmed
by performing test of amylase enzyme. Urea stains may be detected by the odor
of the stain as well as under ultra violet radiation to have fluorescence. To confirm
the presence of urine, urea nitrate crystal test, creatinine test can be conducted.
WhatsApp