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FORENSIC SCIENCE
PAPER No.12: Forensic Biology & Serology
MODULE No.4: Introduction of Biological Fluids and their types
SUBJECT FORENSIC SCIENCE
Paper No. and Title Paper No. 12: Forensic Biology & Serology
Module No. and Title Module No. 4: Introduction of Biological Fluids and Their Types
Module Tag FSC_P12_M4
FORENSIC SCIENCE
PAPER No.12: Forensic Biology & Serology
MODULE No.4: Introduction of Biological Fluids & Their Types
TABLE OF CONTENTS
Biological Fluids
Forensically important Biological fluids
Blood
Semen
Saliva
Urine
Vaginal Secretions
Feces
FORENSIC SCIENCE
PAPER No.12: Forensic Biology & Serology
MODULE No.4: Introduction of Biological Fluids & Their Types
Learning Outcomes
After studying this module:
You should be able to identify various forensically important biological fluids.
You should develop an overview of a number of biological fluids commonly analyzed in
forensic science laboratories.
You should understand basic components of Blood, Semen, Saliva, Urine and other
forensically important biological fluids.
You should also be able to appreciate the use of these biological fluids in forensic casework.
Introduction – Biological Fluids and their types
Human body is largely composed of water. Life, as we see it, cannot become viable without water.
A large variety of fluids are secreted inside and outside of the body. They include more than 28
different fluids such as blood, semen, saliva, milk, tears, sweat, urine, etc.
List of biological fluid produced by the human body
• Amniotic fluid
• Aqueous humour and
vitreous humour
• Bile
• Blood serum
• Breast milk
• Cerebrospinal fluid
• Cerumen (earwax)
• Endolymph and
perilymph
• Exudates
• Feces
• Gastric juice
• Lymph
• Mucus
• Pericardial fluid
• Peritoneal fluid
• Pleural fluid
• Pus
• Rheum
• Saliva
• Sebum (skin oil)
• Semen
• Sputum
• Synovial fluid
• Tears
• Sweat
• Vaginal secretion
• Vomit
• Urine
FORENSIC SCIENCE
PAPER No.12: Forensic Biology & Serology
MODULE No.4: Introduction of Biological Fluids & Their Types
Human body produces large variety of fluids
both inside and outside the body. Some of these
fluids are extensively used in the forensic
analysis to solve crime case.
The common biological fluid that a forensic
science lab examines include, blood, semen,
saliva, urine. In addition, the examination of
vaginal secretions and faeces is also conducted in
appropriate cases.
1. Blood
Blood is a fluid connective tissue in the body. It has several functions including transport of
molecules across the body, maintenance of body temperature, provide immunity to the
body, etc.
Blood is composed to two main component. Cellular part and Serum part as fluid part.
The cellular part further consists of Red Blood Cells (also known as erythrocytes), white
blood Cells & Platelets.
RBCs impart red color to blood due to the presence of iron containing protein haemoglobin
which transports oxygen and carbon dioxide. More precisely, RBCs enriched with oxygen
are red colored while RBCs devoid of oxygen are slightly purplish. This is the reason why
veins in the body appear bluish because they carry de-oxygenated blood.
FORENSIC SCIENCE
PAPER No.12: Forensic Biology & Serology
MODULE No.4: Introduction of Biological Fluids & Their Types
1.1 Blood Cells
Blood cells can be characterized on the basis of the presence or absence of nucleus.
Mature RBCs and Platelets do not contain nucleus.
Platelets are important cells which are responsible for the clotting of blood.
WBCs, on the other hand, contain nucleus and mitochondria. WBCs contain DNA &
therefore enable a highly useful forensic DNA examination of blood samples.
Various cell types found in blood.
FORENSIC SCIENCE
PAPER No.12: Forensic Biology & Serology
MODULE No.4: Introduction of Biological Fluids & Their Types
FORENSIC SCIENCE
PAPER No.12: Forensic Biology & Serology
MODULE No.4: Introduction of Biological Fluids & Their Types
The process of blood clotting is described in detail in the above image. Platelets are
responsible for starting the clotting process which involves several factors and finally end
in the formation of fibrin polymer which appear as clot.
1.2 Blood groups
Red blood cells possess molecules
called antigens, on their surface.
In addition, antibodies are also present
in blood that recognize their
corresponding antigens. If a wrong
antigen is introduced in the body, it
will be recognized as a foreign
molecule by the antibodies present in
the body. This starts a process for
destroying that foreign antigen. This
process is known as immune response.
Since blood possess these antigen &
antibodies, it can easily be
characterized based on them
Thirty-three major blood group systems (including the AB and Rh systems) were
recognised by the International Society of Blood Transfusion (ISBT). Apart from the ABO
group, there are several other group systems such as Rh, Kell, Duffy, etc.
The most common grouping system is ABO system. ABO system was first discovered by
Karl Landsteiner.
In the A group blood, the RBCs possess A antigen. The plasma of A group blood possesses
Anti-B antibody.
FORENSIC SCIENCE
PAPER No.12: Forensic Biology & Serology
MODULE No.4: Introduction of Biological Fluids & Their Types
List of blood group systems recognized by International Society of Blood Transfusion
(ISBT).
ISBT No System name System symbol Chromosome
001 ABO ABO 9
002 MNS MNS 4
003 P P 22
004 Rh (Rhesus) RH 1
005 Lutheran LU 19
006 Kell KEL 7
007 Lewis LE 19
008 Duffy FY 1
009 Kidd JK 18
010 Diego DI 17
011 Yt or Cartwright YT 7
012 XG XG X
013 Scianna SC 1
014 Dombrock DO 12
015 Colton CO 7
016 Landsteiner-Wiener LW 19
017 Chido/Rodgers CH\ 6
018 Hh/Bombay H 19
019 Kx XK X
020 Gerbich GE 2
021 Cromer CROM 1
022 Knops KN 1
023 Indian IN 11
024 Ok OK 19
025 Raph RAPH 11
026 JMH JMH 6
027 Ii I 6
028 Globoside GLOB 3
029 GIL GIL 9
030 Rh-associated glycoprotein RHAg 6
031 Forssman FORS 9
032 Junior JR 4
033 Langereis LAN 2
FORENSIC SCIENCE
PAPER No.12: Forensic Biology & Serology
MODULE No.4: Introduction of Biological Fluids & Their Types
1.3 Blood as Forensic Evidence
Blood is one of the most significant evidence in
forensic casework.
Blood can establish the connection between a
victim and the criminal. Bloodstain pattern
analysis can reveal the mode of crime and
movement of criminal as well as the victim.
Blood Spatter is a technique to reconstruct the
event that led to the bloodstain. It includes
analysis of the shapes, locations and distribution
of blood stains
DNA analysis of blood sample can fix its origin to a single individual. Blood is also an
important evidence in toxicological analysis of various drugs and alcohol.
2. Semen Semen is a thick, yellowish white, glairy, opalescent,
secretion having a characteristic odor known as seminal
odor.
The fluorescence of the seminal stains is of a bluish white
colour.Semen Identification is useful as evidence in sexual
assault cases. It can prove that the sexual assault crime was
committed. It can also help identify the criminal.
Semen is composed of several components including
sperm cells, enzymes, sugars, minerals, organic chemicals
and vitamins.
Four glands contribute their secretions to the seminal fluid, viz., Testes, Seminal Vesicle,
Prostate and Bulbourethral gland. Bulbourethral gland is also known as Cowper’s gland.
The approximate percentage composition of semen is presented in this table indicating
contributions from various glands.
FORENSIC SCIENCE
PAPER No.12: Forensic Biology & Serology
MODULE No.4: Introduction of Biological Fluids & Their Types
It is important to understand that sperm cells are produced only in the testes. Therefore, if
any person has received vasectomy, then his semen will not contain sperm cells. The other
component, however, would be present as usual.
Table showing percentage contribution of various gland secretions in seminal fluid.
2.1 Forensic Examination of Semen: An overview
As with other forensic exhibits, the investigation of semen is also carried out in a
methodical way using various tests.
First, the screening tests are performed in order to identify whether the questioned stain is
semen or not. Once the preliminary screening tests are positive, a more detailed
confirmatory analysis is carried out to establish that the stain is indeed semen.
Further exhaustive analysis of seminal stains is performed in order to individualize the stain
to a particular individual.
FORENSIC SCIENCE
PAPER No.12: Forensic Biology & Serology
MODULE No.4: Introduction of Biological Fluids & Their Types
2.2 Finding Sperm cells in Semen
The identification of one or more sperms is a conclusive proof of the presence of
semen.
However, there are difficulties in the identification of sperms due to several reasons.
1. If a criminal is oligospermic, then his ejaculate may contain only a few sperms.
2. Another reason could be the condition of Aspermia where no sperms are
produced by the seminiferous tubules of the testes.
3. If the criminal has undergone Vasectomy which is the surgical procedure for
male sterilization to prevent sperm from entering into the seminal stream.
4. In addition to these, there may be other reasons such as sperms trapped in the
clothing not extracted into the testing extracts.
5. Disintegration of sperms can also take place during handling of the material,
etc.
Finding sperm cells in body cavities of a victim of sexual crime is the utmost priority
for obvious reasons. Several research findings indicate that motile and non-motile
sperms can be obtained at different duration in different body cavities. For example,
motile sperms can be obtained from the vaginal swabs of a victim within 6 to 28 hours
of the assault. However, non-motile sperms (which are devoid of flagella) can be
obtained for upto 10 days in vaginal cavity in certain cases.
FORENSIC SCIENCE
PAPER No.12: Forensic Biology & Serology
MODULE No.4: Introduction of Biological Fluids & Their Types
The table below shows the approximate duration for which motile and non-motile
sperms can be found in the body cavities of a victim of sexual crime.
Maximum reported recovery times for spermatozoa collected from body cavities ¡n
living sexual assault victims
3. Saliva
Saliva is a fluid largely composed of water with
little amounts of electrolytes and enzymes. It is
secreted by a pair of salivary glands in the mouth.
Saliva is rich in the enzyme alpha-amylase (also
known as α-amylase, salivary amylase, or Ptyalin).
Ptyalin enzyme breaks down complex
carbohydrates into smaller sugar molecules.
Forensically, it is often seen in sexual assault
cases. Saliva tests can reveal certain disease
markers, viral infections, and the presence of
therapeutic as well as illicit drugs in the body.
Saliva samples can be analyzed from various types
of surfaces such as body parts, paper, envelopes,
cigarette butts, plastic and glass bottles, and metal
cans, etc.
FORENSIC SCIENCE
PAPER No.12: Forensic Biology & Serology
MODULE No.4: Introduction of Biological Fluids & Their Types
3.1 Examination of Saliva
Saliva is an important evidence which can
provide useful information about the
personal contact of victim and
perpetrator.
The presence of saliva can be ascertained
by Starch-iodide and Phadebas tests.
Starch-iodide and Phadebas tests,
however, do not confirm the presence of
Human saliva. These are merely the test
for amylaze activity regardless of whether
that amylase has come from human or any
other source.
An advanced, monoclonal antibody based
test kit is used to identify human specific salivary
amylase. With RSID method, if a stain gives
positive reaction, then it is confirmed that human
saliva is present.
In addition, ABO group antigens can also be
detected in saliva, if the person is secretor. A secretor is an individual whose saliva and
other body fluids contain ABO antigens. Approximately 80% individuals are known to
be secretors.
FORENSIC SCIENCE
PAPER No.12: Forensic Biology & Serology
MODULE No.4: Introduction of Biological Fluids & Their Types
Finally, since saliva may also contain buccal mucosa cells, it is possible to identify the
DNA profile of the person in question using advanced DNA profiling techniques.
4. Urine: Content and Identification Urine is an important biological liquid for forensic
analysis. A suspected urine stain may fluoresce
pale yellow or pale blue when viewed under long
and short wave UV light.
Characteristic odor of urine may be detected by
placing a small sample of the stain in a test tube
and heating slightly.
Urine contains two main constituents, namely,
Urea and Creatinine. Both these components are
tested for confirming the presence of urine. Urea
Nitrate Crystal test & Creatinine Test are
employed for such testing.
Urine is also an important exhibit for forensic
toxicology analysis. Almost all toxicants or their
metabolites can be analysed in urine samples using
various analytical procedures.
5. Vaginal Secretion & Faeces
Vaginal secretions contain a mixture of cells and liquid. Vaginal Secretions, appear
stiff on feeling when these are on clothing, under UV light examination, these show
fluorescence.
Vaginal secretion contain squamous epithelial cells that are rich in glycogen. This
enables them to be identified using Lugol’s iodine test.
FORENSIC SCIENCE
PAPER No.12: Forensic Biology & Serology
MODULE No.4: Introduction of Biological Fluids & Their Types
In addition to cells, vaginal secretion also contains acid phosphatase enzyme.
However, the acid phosphatase enzyme is much less as compared to the semen.
Therefore, it gives weak positive for acid phosphatase.
Faeces is a product of digestion. It is composed of
digested waste, undigested food, cells, organic
degradation products such as indole and skatole, etc.
In addition, faeces also contain Urobilinogen, which is
a colorless product of bilirubin reduction. About half
of the urobilinogen is excreted in faeces.
Urobilinogen is frequently tested in order to confirm the presence of faecal stains.
Forensically, vaginal secretions and faeces have limited use because of the difficulty in
analysis and lack of specificity in many forensic situations.
Summary:
1. Various Biological fluids produced by Human Body.
2. RBCs impart red color to blood due to the presence of iron containing protein
haemoglobin which transports oxygen and carbon dioxide.
3. Blood cells can be characterize on the basis of presence or absence of nucleus.
4. Red blood cells possess molecules called antigens, on their surface.In addition,
antibodies are also present in blood that recognize their corresponding antigens.
5. DNA analysis of blood sample can fix its origin to a single individual.
6. The fluorescence of the seminal stains is of a bluish white colour.
7. Saliva is rich in the enzyme alpha-amylase (also known as α-amylase, salivary
amylase, or Ptyalin).
8. A suspected urine stain may fluoresce pale yellow or pale blue when viewed under
long and short wave UV light.
9. Vaginal secretion contain squamous epithelial cells that are rich in glycogen.
10. Urobilinogen is frequently tested in order to confirm the presence of faecal stains.