Unit 5 forensics - Kowenscience.com

Unit 5: Forensic Anatomy
• This unit will cover the various body systems that can be used for
forensic identification in various criminal investigations.
• Body fluids
• Topics covered will include: blood, blood typing and identification
and blood splatter analysis
• Hair analysis
• Fingerprints
• bone and skeletal remains
• DNA evidence
• About 8% by weight of the average human body is blood.
• This corresponds to about 5 L in the average person.
• The three types of cells are erythrocytes (red blood cells,
RBC), leukocytes (white blood cells), and thrombocytes
(blood platelets).
Serology is the examination and analysis of body fluids.
A forensic serologist may analyze a variety of body
fluids including saliva, semen, urine, and blood.
From 1950 to the late 1980’s, forensic serology was a
most important part of lab procedures.
With the development of DNA techniques, more time,
money, and significance was placed in developing DNA
However, with limited funds and the time required for DNA
testing, most labs still use many of the basic serology
testing procedures.
Chapter 10
Blood Characteristics
Chapter 10
 Plasma is the fluid portion of
the blood (55%) (92% water)
 Cells (45%)
 Erythrocytes are red
blood cells. They are
responsible for oxygen
 Leukocytes are the white
blood cells; they are
responsible for
“cleaning” the system of
foreign invaders.
 Thrombocytes or
platelets are responsible
for blood clotting
 Serum is the liquid that
separates from the blood
when a clot is formed.
Blood Terminology
 ABO blood groups—based on having an A, B, both or no
antigens on red blood cells
 Rh factor—may be present on red blood cells; positive if
present and negative if not
 Antigen—a substance that can stimulate the body to make
antibodies. Certain antigens (proteins) found in the plasma of
the red blood cell’s membrane account for blood type.
 Antibody—a substance that reacts with an antigen
 Agglutination—clumping of red blood cells; will result if blood
types with different antigens are mixed
Chapter 10
Unknown Stain at a Scene
Questions to be answered:
 Is it blood?
 Is it human blood?
 Whose is it?
 Determine blood type, alcohol
content, drugs present
 Determine the method(s) in
which blood may have been
Chapter 10
Presumptive Tests for
Blood Determination
 Is: The generic term for any way of determining
if a stain is blood.
 Kastle-Meyer color test—a mixture of
phenolphthalein and hydrogen peroxide; the
hemoglobin will cause the formation of a deep pink
color if blood is present
 Hematest® tablet—reacts with the heme group in
blood causing a blue-green color
 Luminol test—reaction with blood to produce light
Chapter 10
Human vs Animal Blood
 Microscopic observation
 Precipitin test—blood is injected into a rabbit;
antibodies are formed; the rabbit’s blood is
extracted as an antiserum; the antiserum is
placed on sample blood. The sample will react
with human proteins, if human blood is present.
This test is very sensitive and requires only a
small amount of blood.
Chapter 10
Animal Blood
Larger nucleic red
blood cells
Frog Blood
Chapter 10
Human Blood
 Red blood cells are most
numerous; 5 to 6 million
per mm3
 White blood cells are
larger and less numerous;
5 to 10,000 per mm3
 Platelets are tiny, cellular
fragments; 350 to 500,00
per mm3
Chapter 10
Blood Typing
Chapter 10
 Blood type A has antigen A on the surface of
the cell and will agglutinate with blood type B.
 Blood type B has antigen B on the surface of
the cell and will agglutinate with blood type A.
 Blood type AB has antigens A and B on the
surface of the cells and will not agglutinate with
either type A or B blood.
 Blood type O has neither antigen A or B and
will not agglutinate.
 The temperature used to break the antigen –
antibody bond is 54C
Blood Typing
 1901 Karl Landsteiner discovered the ABO
blood groups.
 1915 Leone Lattes developed a method of
typing dried blood stains.
 The procedure is called the absorptionelution method, and dried blood spots are
collected using a cotton swab moisten with
distilled water.,
Chapter 10
Blood Groups
Chapter 10
Antibody Can Give
Can Get
Blood From
O, A
A and B
A nor B
A, B, O, AB
A nor B
A and B
A, B, O, AB
Blood To
Population Distribution
of Blood Types in the U.S.
Chapter 10
Let's say a piece of fabric is found with a
bloodstain on it.
 A small piece of the fabric is cut off
 The fabric is then put in a small container of normal
saline (a water solution with the same salt concentration
as the human body), and a few drops of anti-A and antiB antibodies are added.
Chapter 10
Chapter 10
The fabric is then removed and washed with normal saline,
removing any antibodies not attached to the bloodstained
It is then placed in a container of fresh saline and heated to a
temperature of 54°C for about 5 min.
This temperature is high enough to break the antibody-antigen
bonds, and the antibodies are released into the saline solution.
Blood type can be determined
Go over punnett square and paternity
Chapter 10
Based on the premise that all bloodstains and
bloodstain patterns
are characteristic of the forces that have created
Blood Spatter Investigation
The success or failure of any criminal investigation often
depends on the recognition of physical evidence left at a
crime scene and the proper analysis of that evidence.
Crime scenes that involve bloodshed often contain a
wealth of information in the form of bloodstains. The
pattern, size, shape, and the location of such stains may
be very useful in the reconstruction of the events that
Bloodstain Pattern Analysis:
The examination of the shapes, locations, and
distribution patterns of bloodstains, in order to
provide an interpretation of the physical events
which gave rise to their origin.
Blood Pattern Reconstruction
Scene Pattern
Lab Results
1. Stain condition
1. Genetic marker typing
2. Pattern
2. Age Determination
3. Distribution
3. Source Determination
4. Location
4. Race Determination
5. Directionality
5. Sex Determination
—From “Cracking Cases” by Dr. Henry C. Lee
Chapter 10
Blood Spatter Evidence
A field of forensic investigation which deals
with the physical properties of blood and
and the patterns produced under different
conditions as a result of various forces
being applied to the blood. Blood, as a
fluid, follows the laws of physics.
Chapter 10
Blood Droplet Characteristics
 A blood droplet will remain spherical in space
until it collides with a surface
 Once a blood droplet impacts a surface, a
bloodstain is formed.
 A droplet falling from the same height, hitting
the same surface at the same angle, will
produce a stain with the same basic shape.
 How will the shape change as the height is
increased or decreased?
Chapter 10
Blood Droplet Volume
 A droplet contains approximately 0.05 cc
of fluid
 Is not the same for all blood droplets, but
is generally from 0.03 cc to 0.15 cc
 Is directly dependent upon the surface or
orifice from which it originates
 The impact area is called the target.
Chapter 10
Conditions Affecting
Shape of Blood Droplet
Size of the droplet
Angle of impact
Velocity at which the blood droplet left its origin
Texture of the target surface
 On clean glass or plastic—droplet will have smooth
outside edges
 On a rough surface—will produce scalloping on the edges
Chapter 10
Questions Answered by
Blood Spatter Interpretation
 The distance between the target surface and the origin
of blood
 The point(s) of origin of the blood
 Movement and direction of a person or an object
 The number of blows, shots, etc. causing the bloodshed
and/or the dispersal of blood.
 Type and direction of impact that produced the
 The position of the victim and/or object during bloodshed
 Movement of the victim and/or object after bloodshed
Chapter 10
Bloodstain Terminology
 Angle of impact—angle at which blood strikes a
target surface.
 Bloodstain transfer—when a bloody object
comes into contact with a surface and leaves a
patterned blood image on the surface
 Backspatter—blood that is directed back toward
the source of energy
 Cast-off—blood that is thrown from an object in
Chapter 10
Bloodstain Terminology
 Contact stain—bloodstains caused by contact
between a wet blood-bearing surface and a second
surface which may or may not have blood on it
 Transfer—an image is recognizable and may be
identifiable with a particular object
 Swipe—wet blood is transferred to a surface which
did not have blood on it
 Wipe—a non-blood bearing object moves through a
wet bloodstain, altering the appearance of the
original stain
Chapter 10
Bloodstain Terminology
 Directionality—relates to the direction a drop of
blood traveled in space from its point of origin
 Terminal velocity—the greatest speed to which a
free falling drop of blood can accelerate in air. It is
dependent upon the acceleration of gravity and the
friction of the air against the blood—approximately
25.1 feet/second.
• High velocity—greater than 25 feet per second, usually 100
feet per second; gives a fine mist appearance
• Medium velocity—5 to 25 feet per second
• Low velocity—5 feet per second or less
Chapter 10
Bloodstain Patterns
The shape of a blood drop:
 Round—if it falls straight down at a 90 degree
 Elliptical—blood droplets elongate as the angle
decreases from 90 to 0 degrees; the angle can
be determined by the following formula:
Chapter 10
 The more acute the angle of
impact, the more elongated the
 90 degree angles are perfectly
round drops with 80 degree
angles taking on a more
elliptical shape.
 At about 30 degrees the stain
will begin to produce a tail.
 The more acute the angle, the
easier it is to determine the
direction of travel.
Chapter 10
Bloodstain Patterns
 The harder and less porous
the surface, the less the
blood drop will break apart.
 The softer and more porous
the surface, the more a blood
drop will break apart.
 The pointed end of the blood
stain faces the direction of
Chapter 10
Area of Intersection
and Convergence
The location of the blood source
can be determined by drawing lines
from the various blood droplets to
the point where they intersect.
The area of convergence is the
point of origin; the spot where the
“blow” occurred. It may be
established at the scene with
measurement of angles by use of
Chapter 10
Blood Evidence
 Class evidence for blood would include blood type.
If you can determine the DNA you would have
individual evidence.
 Blood stain patterns are considered circumstantial
evidence in a court room. Experts could argue
many points including direction of travel, height of
the perpetrator, position of the victim, left/right
hand, whether the body was moved, etc.
Chapter 10
80% of the population are secretors.
Their blood-type antigens are found in
high concentration in their body fluids
such as saliva, semen, vaginal
secretions and gastric juice.
Chapter 10
Bloodstain Pattern Analysis:
The determinations made from bloodstain patterns at the scene or from the
of principals in a case can be used to:
Confirm or refute assumptions concerning events and their sequence:
Confirm or refute statements made by principals in the case:
Position of victim. (standing, sitting, lying)
Evidence of a struggle. (blood smears, blood trails)
Are stain patterns on a suspects clothing consistent with his reported
Are stain patterns on a victim or at a scene consistent with accounts given
by witnesses or the suspect?
Categories of Bloodstains
A transfer bloodstain is created
when a wet, bloody surface
comes in contact with a
secondary surface.
A recognizable image of all or a
portion of the original surface
may be observed in the
as in the case of a bloody hand
or footwear
Projected bloodstains are
created when an exposed
blood source is subjected to an
action or force, greater than
the force of gravity.)
The size, shape, and number of
resulting stains will depend,
primarily, on the amount of
force utilized to strike the
blood source
This category can be further subdivided to
Arterial Spurt / Gush
Bloodstain pattern(s)
resulting from blood
exiting the body under
pressure from a breached
Cast Off Stains
Blood released or thrown from a bloodbearing object in motion
Cast-off Stains
Impact Spatter
Blood stain patterns created when a blood source
receives a blow or force resulting in the random
dispersion of smaller drops of blood.
This category can be further
subdivided into
Low Velocity
Gravitational pull up to 5
Relatively large stains 4mm in
size and greater
Usually result of blood dripping
from person standing still,
walking/running, or castoff
Usually around 90 degree angle
Medium Velocity
Force of 5 to 25 feet/sec.
 Preponderant stain size 1
to 4mm in size
 Often caused by blunt or
sharp-force trauma ( knife,
hatchet, club, fist, artery spurt
High Velocity
Force of 100 feet/sec. and
Preponderant stain size
1mm in size and smaller
Mist like appearance
Ex gunshot, coughing,
sneezing or explosives
When a droplet of blood strikes a surface perpendicular
(90 degrees) the resulting bloodstain will be circular.
That being the length and width of the stain will be equal.
 Blood that strikes a surface at an angle less than 90
degrees will be elongated or have a tear drop shape.
Directionality is usually obvious as the pointed end of the
bloodstain ( tail ) will always
point in the direction
ANGLE of IMPACT is the acute angle formed
between the direction of the blood drop
and the plane of the surface it strikes
By utilizing trigonometric
functions its possible to
determine the impact
angle for any given blood
Sin = length(mm)
Width (mm)
Saliva :
Saliva is becoming more and more useful
as physical evidence. In the past, it was
mostly used to determine blood type.
 saliva from a secretor can be used to
determine their blood type.
 Evidence such as cigarette butts, chewing
gum, bite marks, envelopes, and stamps
should be packaged in clean paper or a
paper bag. If the evidence is damp, it
should be air-dried before packaging.
Saliva residues can be removed from
immovable objects using a moistened
cotton swab.
In the case of sexual crimes one of the most
important pieces of physical evidence for the
investigator to discover is the presence of seminal
fluid (semen)..
 When the scene of a sexual crime is searched, it is
customary to first try to locate any seminal stains.
This can be accomplished using ultraviolet (UV) light since
seminal stains fluoresce under UV light.
 Suspected stains can be tested using a piece of filter
paper moistened with a solution of sodium naphthol
phosphate or Fast Blue B. Both these chemicals change
color on reacting with the acid phosphatase present in
Chapter 5:
“For three days after death, hair and
fingernails continue to grow but
phone calls taper off.”
—Johnny Carson
Comedian and television host
 Human hair is one of the most frequently
found pieces of evidence at the scene of a
violent crime. It can provide a link between
the criminal and the crime.
 From hair one can determine:
If the source is human or animal
Race (sometimes)
Origin of the location on the source’s body
Whether the hair was forcibly removed
If the hair has been treated with chemicals
If drugs have been ingested
Skin Structure
‡ Hair is composed mostly of protein produced from
the hair follicle.
‡ The follicle is fed by tiny blood vessels
‡ Hair can be used for drug analysis because
anything present in the bloodstream is also
incorporated into the hair.
‡ The protein of the hair is keratinized, which makes
it very strong.
Components of Hair
 Human
hair has 3 layers called the cuticle, cortex
and medulla.
 The cuticle is the outermost layer of hair.
 The cuticles of different species display different
 Forensic scientist can analyze the cuticle pattern
of any hairs left at the crime scene to determine
Hair Shaft
Composed of:
 Cuticle—outside covering, made
of overlapping scales
 Cortex—inner layer made of
keratin and imbedded with
pigment; also contains air sacs
called cortical fusi
 Medulla—inside layer running
down the center of the cortex
Basic Structure of Hair
The Cuticle
The cuticle is the outermost layer of hair which is
covered with scales. The scales point toward the tip of
the hair. Scales differ between species of animals and
are named based on their appearance. The three
basic patterns are:
 Coronal
 Spinous
 Imbricate
three basic scale structures that make up the
imbricate (flattened)
spinous (petal-like)
coronal (crown-like)
Human Scales
In order to visualize the
 paint clear fingernail
polish on a glass slide
 when the polish begins
to dry, place a hair on
the polish
 when almost dry, lift off
the hair and observe
the scale imprints
What pattern is seen in
this slide?
The Cortex
The cortex gives the hair its shape.
It has two major characteristics:
 Melanin—pigment granules that give hair its
 Cortical fusi—air spaces, usually found
near the root but may be found throughout
the hair shaft
The Medulla
The medulla is the hair core that is not
always visible. The medulla comes in
different types and patterns.
 Intermittent or interrupted
Absent—not present
Human Medulla
Human medulla may be continuous,
fragmented or absent.
Medullary Index
Determined by
measuring the diameter
of the medulla and
dividing it by the diameter
of the hair.
 Medullary Index for human
hair is generally less than 1/3.
 For animal hair, it is usually
greater than 1/2.
Hair Shape
Can be straight, curly or kinky depending on the
cross-section, which may be round, oval or
Crescent moon
Hair Growth
 Anagen—hair that is actively growing; lasting up to 5 years
 Catagen—hair is not growing; a resting phase
 Telogen—hair that is dying and ready to fall out; lasting two to six months
Length—about 0.5 mm per day or 1 centimeter per
month; approximately one half inch per month
The Root
Human roots look different based on
whether they have been forcibly removed
or if they are telogen hairs and have fallen
out. Animal roots will vary, but in general
have a spear shape.
Fallen out
Forcibly removed
Hair Comparison
Distribution, shape and
color intensity of pigment
 Dyed hair has color in
cuticle and cortex
 Bleaching removes pigment
and gives a yellow tint
 Scale types
 Presence or
absence of
 Medullary type
 Medullary pattern
 Medullary index
DNA from Hair
 The root contains nuclear DNA. If the hair has been
forcibly removed, some folicular tissue may be attached
containing DNA.
 The hair shaft contains abundant mitochondrial DNA,
inherited only from the mother. It can be typed by
comparing relatives if no DNA from the body is
available. This process is more difficult and costly than
using nuclear DNA.
Collection of Hair
 Questioned hairs must be accompanied by an
adequate number of control samples.
 from victim
 from possible suspects
 from others who may have deposited hair at the scene
 Control Sample
 50 full-length hairs from all areas of scalp
 24 full-length pubic hairs
Hair Toxicology
 Napoleon died in exile in
1821. By analyzing his
hair, some investigators
suggest he was
poisoned by the
deliberate administration
of arsenic; others
suggest that it was
vapors from the dyes in
the wallpaper that did
him in.
Caucasian Hair
This is a human head
hair of Caucasian origin.
Caucasian hairs come in
the widest variety of
colors, can be of fine to
medium coarseness and
are generally straight or
In addition, the shafts vary
from round to oval in cross
section. Finally, color
pigments are fine- to
medium-sized and are
evenly distributed
throughout the shaft
Caucasian hair
Photomicrograph of
Caucasian Head Hair
Photomicrograph of
Beard Hair Medulla
African American
This is a human head hair
of Afro-Caribbean origin.
Such hairs are generally
curly or kinky, and have a
flattened cross section.
Larger than those of other
racial groups, its pigment
particles are grouped in
clumps of different sizes
and shapes and may be so
dense that they render the
hair opaque.
Furthermore, the hair
shaft may vary — or seem
to vary — in diameter
because of its flattened
nature and the way it
settles on the microscope
Top right photo is hair with lice eggs, Bottom photo of recently cut hair(Left) and
of a hair sample with split ends (
Artificial treatment
Bleaching removes
pigment from the hair and
can give the hair a
characteristic yellow cast
dyed hairs possess an
unnatural cast or color. In
addition, the cuticle will
take on the color of the
This is a human head hair of
Asian origin.
Such hair is generally coarse,
straight and circular in cross
section. Its diameter is wider
than the hair of other racial
groups, and the outer layer of
the hair, the cuticle, is usually
significantly thicker.
The medulla, or inner layer of
cells, is continuous and wide.
In addition, the hair shaft
contains pigment particles
that are generally larger than
those of Caucasian hairs, and
often appear to be grouped in
patchy areas.
Finally, the hair may have a
reddish appearance, a product
of its pigment
Animal vs Human hair samples
Humans have a very fine cuticle pattern, called imbricate,
with overlapping shingles of cuticles always point toward
the tip.
 Animal hair often has much rougher cuticles, such as
spinous or coronal.
 Spinous cuticle patterns are found on the hair of cats,
minks, seal but not on humans.
 Coronal cuticle patterns are found on the hair of rodents
and bats
Spinous or petal-like scales
Spinous or petal-like scales
are found at the proximal
region of mink hairs and
on the fur hairs of seals,
cats, and some other
left is mink, below
is seal
coronal (crown-like),
 Coronal
scales are commonly found in the hairs of
small rodents and bats but rarely in human hairs.
Imbricate Scales
The imbricate or flattened
scales type consists of
overlapping scales with
narrow margins.
They are commonly found
in human hairs and many
animal hairs
Lion Hair
Deer hair
This is a deer hair. Unlike
that of any other animal,
the root of deer hair has a
wine-glass shape: a
narrow root that gradually
In addition, the medulla,
or inner layer of cells,
consists of spherical cells
that take up the whole
width of the hair in a
repeating pattern of
different shapes, such as a
hexagonal shape,
depending on what
member of the deer family
the subject belongs to
Cat Hair
This is a cat hair.
 Cat hair has
fibrous roots and
its pigment
particles do not run
down to the root.
 In addition, its
medulla, or inner
layer of cells, is
thicker than that of
dog hair
Dog Hair
This is a dog hair.
Dog hair has spadelike roots and its
pigmentation runs
down throughout the
shaft to the root.
Its medulla, or inner
layer of cells, is
thinner, too, than that
of cat hair
Muskrat hair

similar documents