LAW 544: FORENSIC SCIENCE

OCT 2022- FEB 2023

WEEK 2 (17-23 OCTOBER)

CHAPTER 2:
FORENSIC BIOLOGY

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 CONTENTS 2

PART I
2.1 POST-MORTEM AND IDENTIFICATION OF DEATH AND TIME
OF DEATH.
2.2 THE HUMAN SKELETON AND DETERMINATION OF SEX
FROM SKELETON.

PART II
2.3 SCIENTIFIC EXAMINATION OF RAPE VICTIMS AND
ACCUSED.
2.4 IDENTIFICATION OF HUMAN AND ANIMAL HAIR AND
IDENTIFICATION OF BLOOD TYPES.
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WHAT IS FORENSIC
BIOLOGY ?
 Forensic biology is the application of
biology to law enforcement.
 It includes the sub disciplines of
Forensic anthropology, Forensic
botany, Forensic entomology,
Limnology, Forensic serology,
Forensic odontology, wildlife forensic
and DNA forensics.

 Forensic Biology is the application of

concepts and procedures used in the
biological sciences, typically in a
medico-legal context.

 Forensic biologists examine

biological evidences such as blood
and other bodily fluids, hair, bones,
insects and plant and animal
remains(c) D.Shankar
to help2022
identify victims and Sources: González et.al (2019) 3
support criminal investigations.
 2.1 POST-MORTEM AND
IDENTIFICATION OF DEATH
AND TIME OF DEATH.

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 2.1.1
A surgical procedure performed by a pathologist on a
dead body to ascertain—from the body, organs, and
POSTMORTEM OR bodily fluids—the cause of death.

AUTOPSYAND Simply the examination of a body after death.

IDENTIFICATION
X-ray examinations can be very useful in the autopsy
process.

OF DEATH
The autopsy can be further described as one of two
types:

• A clinical/hospital autopsy
• Focuses on the internal organ findings and medical conditions.
FORENSIC PATHOLOGISTS
• Its purpose is to confirm the clinical diagnoses, the presence and
extent of disease, any medical conditions that were overlooked, and
Investigative personnel, typically the appropriateness and outcome of therapy.
medical examiners or coroners, who
investigate the cause, manner, and • Forensic/medicolegal autopsy
time of death of a victim in a crime; • Determine the cause of death and confirm the manner of death,
can also be a physician who has often to be used in criminal proceedings.
• The forensic autopsy usually emphasizes external and internal
been trained to conduct autopsies. findings while developing meaningful forensic correlations between
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sustained injuries and the crime scene.
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 Fingernail scrapings or Combings from head Buccal swab (for DNA
Victim’s clothing
clippings and pubic areas typing purposes)

Swabs of body areas,

such as breasts or Hand swabs from
Vaginal, anal, and oral
Bullets recovered from penis, suspected of shooting victims (for
swabs (in sex-related
the body being in contact with gunshot residue
crimes)
DNA arising from analysis)
touching or saliva

All evidence must be carefully noted, described,

and photographed!!!
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A broad overview of the condition of the body and the clothing.

Obvious damage to the clothing should be matched up to injuries on the body.

General characteristics: sex, height, weight, approximate age, color of hair, and physical condition.

The mouth and nose are examined for the presence of vomit and or blood and trace evidence, and the ears are examined
for blood.

Any irritations in the nasal cavity can be indicative of drug sniffing.

Often, paper bags are placed over the hands at the crime scene until it is time to examine them.
• This prevents contamination and possible loss of trace evidence, such as hairs and fibers.
• A victim will sometimes have skin and DNA under his or her fingernails from fighting with the assailant.

The external examination also consists of classifying the injuries.

• Distinguishing between different types of wounds, such as a stab wound versus a gunshot wound.
• The injuries that are examined may include abrasions, contusions, lacerations, and sharp-injury wounds.
• The discharge from a firearm will produce characteristic markings on the skin.

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Entails weighing, dissecting, and sectioning each organ of the body.

Microscopic examination of the sectioned organs is conducted, which can help in determining the cause of death.

Special care is taken to identify any preexisting conditions or malformations in the organs that might have
contributed to the death of the victim.

Special attention is paid to the digestive tract if poisoning is suspected.

Chemical analyses can also be carried out to show signs of poisoning.

The internal examination is also where toxicological specimens are taken.

• Blood, stomach content, bile, urine, brain matter, liver, and vitreous humor.
• Poisoning or drug abuse cases

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 Source:
https://www.spiegel.de/international/eur
ope/new-virtual-autopsy-procedure-is-
changing-forensics-a-875657.html

Source: https://timesofindia.indiatimes.com/city/delhi/virtual-
autopsy-no-cuts-to-body-no-hurt-
feelings/articleshow/67606587.cms
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 Sudden death cause is unknown

Deaths require police

Body found dead

investigation Death result from accident - MVA,

animal, persons, machinery etc

Death caused by someone

Death from violence or criminal act or

omission

Death suicides, poisons

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 Source:
Standard Operating Procedures
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2.1.2 Algor mortis
TIME OF DEATH  A process that occurs after death in which the body
temperature continually cools until it reaches the
ambient or room temperature.
 A pathologist can never give an  This is the most useful single indicator of the time of
exact time of death. death during the first 24 hours postmortem (ASAP).
 Determine as best as possible what the environmental
 However, there are many temperatures may have been prior to discovering the
characteristics that the examiner body.
can analyze in order to arrive at  The normal oral temperature fluctuates between 35.9oC
an approximate time of death. (96.7oF) and 37.2oC (99oF). The rectal temperature is
from 0.3-0.4oC (0.5o-0.75oF) higher.
 The chemical and physical  Since heat production ceases soon after death but loss of
changes that occur after death heat continues, the body cools.
must also be examined.  The body loses heat at a rate of approximately of 1–1.5°F
per hour until the body reaches the ambient or room
 Algor mortis, Livor mortis, Rigor temperature.
mortis, Potassium eye levels,  However, the rate of heat loss is influenced by factors
stomach contents, & such as ambient temperature, the size of the body, and
the victim’s clothing. 13
Decomposition (c) D.Shankar 2022
 A medical condition that occurs after death (circulation
ceases) and results in the settling of blood in areas of the
body closest to the ground.
 When the human heart stops pumping, the blood begins
to settle in the parts of the body closest to the ground
(depends on the pressure)
 The skin becomes a bluish-purple color (lividity pattern)
in these areas.
 The onset of this condition begins 20 minutes to 3 hours
after death and under average conditions continues for
up to 16 hours after death, at which point all lividity, or
coloring, is fixed.
 Different lividity patterns in a body may indicate that the
body was moved after death but before livor mortis had
fully fixed.
 The skin does not become discolored in areas where the
body is restricted by either clothing or an object pressing
against the body.
 This information can be useful in determining whether
the victim’s position was changed after death.
 Livor that is a deep purple is often seen in cases where
the victim suffered asphyxia or heart failure. Source: https://www.sciencedirect.com/topics/medicine-
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 A medical condition that occurs after death and
results in the stiffening of muscle mass.

The rigidity of the body begins within 24 hours of

death and disappears within 36 hours of death.

Rigor will develop in the position that the body was

in at the time of death, essentially freezing the body
in that pose.

Discovering a body in a position that defies gravity is

a likely indicator that the body was moved after
death.

Because rigor mortis occurs as a result of the

muscles stiffening, individuals with decreased
muscle mass may not develop rigor completely.

Examples of these individuals may be infants or

elderly or obese persons.
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  Determine potassium levels in the decedent’s
ocular fluid, that is, the fluid within the eye,
also known as the vitreous humor.
 It is important to draw a clean, bloodless
vitreous sample from one eye with a syringe as
soon as possible at the scene, then draw a
second sample from the other eye an hour or
Potassium two later.
 After death, cells within the inner surface of the
Eye Levels eyeball release potassium into the ocular fluid.
 By analyzing the amount of potassium present
at various intervals after death, the forensic
pathologist can determine the rate at which
potassium is released into the vitreous humor
and use it to approximate the time of death.
 However, the rate of potassium release also is
dependent
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Special attention must be paid to the digestive tract.

The identification of food items in the stomach may help determine the location of the
decedent prior to death (during his or her last meal).

The quantity, consistency, and color of bile and the degree of digestion of food in the
stomach and its passage into the small intestine can help determine the time of death.

The stomach also can contain partially digested or dissolved pills.

Chemical analyses can be carried out to identify and analyze substances found in the
stomach.

These can aid in the determination of cause and manner of death.

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 2.2
THE HUMAN SKELETON AND
DETERMINATION OF SEX FROM
SKELETON.

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 2.2.1 THE HUMAN SKELETON

The femur, or thighbone, is

The human hand,
The adult human body has There are 26 bones in the the longest and strongest
including the wrist,
206 of them. human foot. bone of the human
contains 54 bones.
skeleton.

Arms are among the most

commonly broken bones, Bones stop growing in The only bone in the
The stapes, in the middle
accounting for almost half length during puberty. human body not connected
ear, is the smallest and
of all adults' broken bones. Bone density and strength to another is the hyoid, a
lightest bone of the human
The collarbone is the most will change over the course V-shaped bone located at
skeleton.
commonly broken bone of life, however. the base of the tongue.
among children.

Bones function as the

Bones are made up of skeleton of the human
calcium, phosphorus, body, allow body parts to
sodium, and other move and protect organs
minerals, as well as the from impact damage. They
protein collagen. also produce red and white
blood cells.
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2.2.2
DETERMINATION OF By examining the pelvis
SEX FROM SKELETON Can be identified accurately 95% of the time.

 Forensic anthropology
• The use of anthropological
knowledge of humans and
skeletal structure to examine
and identify human skeletal
remains.

 Skeletal bones are remarkably

durable and undergo an extremely
slow breakdown process that lasts
decades or centuries.

 An examination of bones may

reveal a victim’s
• Sex, approximate age, race,
height, and the nature of a
physical injury.
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 This is still fairly accurate, but
not as accurate as the pelvis.

Can accurately identify the skull

somewhere between 85 and 90%.

This can be complicated by

By examining several factors:
skull • Incomplete skulls
• Some of the distinguishing
characteristics, such as larger bone
landmarks for muscle attachments in
males, can be easily confused with the
landmarks of more athletic females.
• The larger the muscles, or the more one
uses the muscles, the larger the
landmarks.
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 Source: Saferstein & Roy (2021)

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2.3
SCIENTIFIC • Workflow of inspection, recovery and analysis of evidence

EXAMINATION OF from the crime scene, victims and perpetrator up to the

genetic profile and human identification.
RAPE VICTIMS AND • CSI/ Crime scene investigator (CSI)
ACCUSED.  In charge of collecting and analyzing crime scene
evidence
• The investigation of sex crimes • Medical examination
requires a group of  Forensic medical examiner, medical technician or nurse
multidisciplinary forensic • Interrogation and sampling
professionals focused on the  Done by a law enforcement agent and by the scientific
identification, recovery, police investigator
packing, and analysis of • Evidence analysis laboratory
evidence.  Done by the research scientists specialized in evidence
• This section focuses on the: analysis.
 Recovery of evidence at the
crime scene
 Recovery of evidence on victim
and perpetrator
 Identification of biological
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evidence in the laboratory
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 Recovery of
evidence on
victim and
perpetrator

Recovery of
evidence at the
crime scene

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 Identification
of biological
evidence in the
laboratory

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 • The advantages and
disadvantages of presumptive
and confirmatory tests used in
the laboratory to locate and
identify the type of BE.
• Its application use goes from
general to particular fluid
identification, considering its
destructive nature based on the
analyst’s criteria.
• BE: biological evidence; Bf: bright
field microscopy; Ph: phase
contrast microscopy.

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2.4.1
IDENTIFICATION OF HUMAN
AND ANIMAL HAIR
 Hair is encountered as physical evidence
in a wide variety of crimes.
 However, any review of the forensic
aspects of hair examination must start
with the observation that it is not yet
possible to individualize a human hair to
any single head or body through its
morphology.
 A careful microscopic examination of hair
reveals morphological features that can
distinguish human hair from animal hair.
 The hair of various animals also differs
enough in structure that the examiner Source: Harris & Lee (2019)
can often identify the species.
 Before reaching such a conclusion, Hair evidence is useful in:
however, the examiner must have access
to a comprehensive collection of reference • Helping to establish the scope of the crime scene
standards and the accumulated
experience of hundreds of prior hair
• Placing a perpetrator at a scene
examinations. • Connecting a suspect with a weapon
 Scale structure, medullary index, and • Supporting witness statements
medullary shape are particularly • Connecting crime scene areas
important in hair identification. • (abduction, vehicle used, dump site) 32
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 It can determine if the hair
Hair specimens are also The hair shaft with a follicle
has been dyed, cut in a In some cases, evidence of
understood in forensic can also offer genetic
certain way or pulled out, poisoning shows up in the
research as "class determinations, such as
and where on the body it hair.
characteristic." blood type or DNA.
was located.

Chemical tests can provide

a history of the use of Animal hairs discovered on
Because of its tough outer drugs and other toxins, items of physical evidence Animal hairs do not
coating, hair does not easily indicate the presence of can link a suspect or possess enough individual
decompose. heavy metals, and provide location to a crime of microscopic characteristics
an assessment of violence.
nutritional deficiencies.

Cosmetics such as
shampoos, hair
conditioners, oils used on Bleaching and dying agents
hair have specific are known to disrupt the
ingredients which can be cuticular layer
used for identification
purposes

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 FIGURE A

Cuticle-
Scale
patterns

FIGURE B

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 FIGURE C

FIGURE (c)
D D.Shankar 2022 35
2.4.2  The word blood actually refers to a highly complex mixture of cells, enzymes,
proteins, and inorganic substances.

IDENTIFICATION OF  The fluid portion of blood is called plasma.

 Plasma- The fluid portion of unclotted blood.

BLOOD TYPES.  Functionally, red blood cells transport oxygen from the lungs to the body tissues
and in turn remove carbon dioxide from tissues by transporting it back to the
lungs, where it is exhaled.
• Until the early 1990s, forensic  However, for reasons unrelated to the red blood cell’s transporting mission, on the
scientists focused on blood surface of each cell are millions of characteristic chemical structures called
antigens.
factors, such as A-B-O, as  Antigens impart blood-type characteristics to the red blood cells.
offering the best means for
Antigen
linking blood to an individual.
• A substance, usually a protein that stimulates the body to produce
• What made these factors so antibodies against it.
attractive to the forensic
scientist was that in theory no Antibody
two individuals, except for • A protein that destroys or inactivates a specific antigen; antibodies
are found in the blood serum.
identical twins, could be
expected to have the same Serum
combination of blood factors. • The liquid that separates from theblood when a clot is formed.
• In other words, blood factors are Antiserum
controlled genetically and have
• Blood serum that contains specific antibodies.
the potential of being a highly
distinctive feature for personal Agglutination
36
identification. (c) D.Shankar 2022
• The clumping together of red blood cells by the action of an antibody.
FIGURE E FIGURE F

The antigen
and antibody
components of
normal blood

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Source: Harris & Lee (2019)
TABLE A

TABLE B

Source: Harris & Lee (2019)

38
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All the information in these slides were adopted and altered from various sources.

 Harris, H. A., & Lee, H. C. (2019). Introduction to forensic science and criminalistics. CRC Press.

 Adam, C. (2016). Forensic evidence in court: evaluation and scientific opinion. John Wiley & Sons.

 Rina, M., & Sandeep, M. (2020). A Forensic Guide for Crime Investigators Standard Operating Procedures. LNJN National
Institute of Criminology and Forensic Science.
 Gardner, R. M., & Krouskup, D. R. (2019). Practical Crime Scene Processing and Investigation. CRC Press.

 González, B. R. , Mercado, M. C. , Salas, O. S. , Reyes, J. C. H. , Ramos, M. G. , Esquivel, E. S. , Aguilar, G. C. , & Torres, P.

D. (2019). Biological Evidence Analysis in Cases of Sexual Assault. In O. Boldura, C. Baltă, & N. S. Awwad (Eds.), Biochemical
Analysis Tools - Methods for Bio-Molecules Studies. IntechOpen. https://doi.org/10.5772/intechopen.82164
 https://www.intechopen.com/chapters/66704

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