Forensic Medicine: Undergraduate

1. Dr Muhammad Wasif
Forensic Med Deptt.

2.  Forensic serology is the application of immunological
and biochemical methods to identify the presence of a
body fluid or tissue sample.
 It deals with the investigation of a crime and the
possible further genetic characterization of the
sample.

3.  Definition
 Forensic serology thus is the study and
examination of body fluids such as blood,
semen, sweat, urine, saliva, fecal matter, and
other fluids mainly for identification purposes
in criminal/medicolegal investigations.
 Blood is the most commonly recovered and
one of the most important pieces of evidence
utilized in forensic investigations. It is
commonly recovered in cases of homicide,
assault, and terrorist attacks, including bomb
blasts.

4.  Blood is the most commonly recovered and one of the
most important pieces of evidence utilized in forensic
investigations.
 It is commonly recovered in cases of homicide, assault,
and terrorist attacks, including bomb blasts.

5.  Blood as evidence holds significance in the
criminal justice system as it can link a crime
with a criminal or exclude an individual’s
involvement in a crime.
 Moreover, the pattern of blood stains can help
in reconstruction of a crime scene by conveying
information about the relative position and
movement of the criminal and victim at the
crime scene.
 Medical science is more interested in white
blood cells, while Forensic science is more
interested in red blood cells and serum.

6.  In forensic science, Locard's principle holds that the
perpetrator of a crime will bring something into the
crime scene and leave with something from it, and
that both can be used as forensic evidence.."

7.  Dr. Edmond Locard (1877–1966) was a pioneer in
forensic science who became known as the Sherlock
Holmes of Lyon, France.[1] He formulated the basic
principle of forensic science as: "Every contact leaves a
trace".
 It is generally understood as "with contact between
two items, there will be an exchange

8. Most well known and significant evidence in modern
criminal justice system. Because
 It can link a victim to a suspect ( via Locard’s
Exchange Principle)
 Bloodstain patterns reveal great deal about position
and movement during crime.
 It managed to destroy self defense arguments of
suspects.

9. GENERAL CHARACTERISTICS
 Slightly alkaline fluid
 Fluid portion of blood consists of plasma and serum
 Non fluid portion consists of 3 types of blood cells i-e Red
blood cells, White blood cells and Platelets.
 Blood is composed of
1. Water
2. Cells
3. Enzymes
4. Proteins
5. Other organic substances

10.  Most prevalent blood cells in the human body
 Deliver oxygen from the lungs to the body’s tissues
 Forensic analyst search for smaller chemical substance
residing on their surfaces (antigens) which also tend to
have important forensic implications

11.  Characterized by its yellow hue, and contains white
blood cells and platelets
 Forensic analysts are able to determine the freshness of
blood sample by its serum since it clots several
minutes after being exposed to air
 A centrifuge can be used to separate the clotted
material from the serum portion
 Serum contains antibodies, protein floating in the
blood fluid which have important forensic
implications

12.  Blood group is a classification of blood, based on the
presence and absence
of antibodies and inherited antigenic substances on the
surface of red blood cells (RBCs). These antigens may
be proteins, carbohydrates, glycoproteins, or glycolipids,
depending on the blood group system. Some of these
antigens are also present on the surface of other types
of cells of various tissues. Several of these red blood cell
surface antigens can stem from one allele (or an
alternative version of a gene) and collectively form a
blood group system.

13.  The ABO blood group system is used to denote the
presence of one, both, or neither of the A and
B antigens on erythrocytes
 The ABO blood types were first discovered by Karl
Landsteiner in 1900
 He found that red blood cells would clump together
(agglutinate) when mixed in test tubes with sera from
different persons, and that some human blood also
agglutinated with animal blood

15.  Blood typing requires 2 antiserums
1. Anti A serum
2. Anti B serum
 A blood agglutinated by anti A serum
 B blood agglutinated by anti B serum
 AB blood by both
 O blood by neither

16.  Rhesus (Rh) factor is an inherited protein found on the
surface of red blood cells. If your blood has the protein,
you're Rh positive. If your blood lacks the protein, you're
Rh negative.
 Rh positive is the most common blood type.
 The Rh blood group system is a human blood group
system. It contains proteins on the surface of red blood
cells. After the ABO blood group system, it is the most
likely to be involved in transfusion reactions. The Rh blood
group system consists of 49 defined blood group antigens,
among which the five antigens D, C, c, E, and e are the
most important.

17.  Five specific questions as guidelines for determining
the nature of the crime;
1. Is the sample blood?
2. Is the sample animal blood?
3. If the sample is animal blood, then from which
species did it come from?
4. If the sample is human blood, what type is it?
5. Can the sex, age and race of the source of the blood
be determined?

18.  The task in examination of blood stains is to produce
conclusive proof of their origin by carrying out the
following examination
1. Physical
2. Chemical
3. Microscopic
4. Serological

19. A. Naked eye examination
B. Examination under;
 Dissecting microscope
 Ultraviolet light

20. LUMINOL TEST
 Forensic scientists spray luminol onto surfaces at
crime scenes to detect invisible blood stains. Wherever
the luminol touches blood, it glows, and the glow is
bright enough to be photographed.

22. PHENOLPHTHALEIN (KASTLE- MEYER’S) TEST
 Phenolphthalein is a presumptive test that reacts with the
heme molecule present in blood. A positive reaction gives a
pink color.
 While bloodstains normally appear red-brown in color, the
color of the substrate or the age of a stain may affect the
appearance or visibility of the stain.
 Phenolphthalein tests are typically conducted on suspected
bloodstains prior to collection. While a positive
phenolphthalein reaction is indicative of blood, it is only a
presumptive test and false positives are possible.
 Additionally, the reaction is not species specific. Positive
reactions are not limited to human blood

23. O- TOLIDINE TEST
 A test for the presence of hemoglobin in feces or urine.
The O- Tolidine can be in a solution, in a tablet or
impregnated onto an absorbent paper. A positive test is
the development of green to blue color.
LEUCOMALACHITE GREEN TEST

24.  Haemochromogen Crystal Test
( TAKAYAMA TEST )
 Micro Chemical Test for Hemoglobin;
Spectroscopy

25. 1. Preparation of film
2. Staining of the film (Jenner’s Stain)
3. Examination under microscope (Shape, size and
presence of nucleus in RBCs)
SEX DETERMINATION IN WBCs
Slides are stained with Jenner’s Stain and examination
of WBCs help determining the sex. Blood must be
fresh for this test. WBCs show their feminine trait, a
thin stalked drumstick projection of polymorph
nucleus given the name DAVIDSON BODY.

26. RACE DETERMINATION
Certain racial genetic markers involving protein
and enzyme tests can help establish race.
AGE DETERMINATION
Fetal Hb indicates fetal blood, also alpha-
fetoproetin

27. EDTA is the anticoagulant of choice for blood collection
for DNA extractions.
 It inhibits DNAase activity and does not introduce
volume changes
 Sample should be shipped as early as possible within
24 hours.

28.  Wet blood is more significant than dried blood
because the forensic scientist can perform more tests
to gain insight to the happenings of the crime.
 Blood begins to dry after 3-5 mins of exposure to air.
 As it dries, it changes color from deep red to brown
and black.
 Blood can be categorized into pools, drops, smears or
crusts.

31.  MURDER
Blood on the weapon can be matched against the
blood of the victim.
Blood stains on clothing or person of the accused
can be matched with the victim.
Hair roots found on weapon can be matched with
that of the victim of the accused
 ACCIDENTAL DEATHS (RTA etc.)
Blood stains on the tyre or other parts of the
offending vehicle may give a clue

32.  SEXUAL CRIMES
Blood stains on thighs or private parts of the victim
 PATERNITY DISPUTES
HLA, DNA
 BLOOD OF PREGNANCY/ABORTION
Presence of chronic gonadotrophin

33.  DEATH DUE TO ASPHYXIA
Dark fluid blood in heart chambers
 DEATH DUE TO DROWNING
Alteration in chloride’s content in blood
 DEATH DUE TO POISONING
Cherry pink color in CO poisoning
Brick red in Cyanide poisoning

37.  ARTERIAL BLOOD
Copious
Bright red in color
Spurting
 VENOUS BLOOD
Dark red
Oozes out gradually

38.  ANTEMORTEM BLOOD
Due to presence of fibrin blood effused during life can
be peeled off in scales upon drying.
 POSTMORTEM BLOOD
Blood flowed after death tend to break into powder upon
drying.

39.  Wear protective clothing, gloves, masks and eye
protection as the situation warrants.
 Photographs should be taken from all angles.

44. 1. Sodium fluoride
2. EDTA
3. Potassium oxalate
4. Citrate
5. 4 degrees celsius temp