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Chapter 10
Blood
(this evidence goes way back!)
“Out damned spot!
Out, I say.
Here’s the smell of the blood still,
All the perfume of Arabia will not
Sweeten this little hand.
Oh, Oh, Oh!”
—William Shakespeare’s Lady Macbeth, in Macbeth
I mean, waaaay, waaaaay back!
IN THE BEGINNING…Cain quarreled with Abel his
brother: and it came to pass, when they were in the field,
that Cain rose up against Abel his brother, and slew him.
And the Lord said unto Cain, Where is Abel, thy brother?
And he said, I know not: Am I my brother’s keeper? And
the Lord said, What hast thou done? The voice of thy
brother’s blood crieth unto me from the ground. And now
art thou cursed from the earth, which hath opened her
mouth to receive thy brother’s blood from thy hand.
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Blood
Students will learn:
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That an antibody and
an antigen of different
types will agglutinate,
or clump, when mixed
together.
That the significance of
the evidence depends
on a characteristic’s
relative occurrence in
the population.
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Blood
Students will be able to:
Explore bloodstain
patterns as a function
of velocity, direction,
and height of fall.
Use technology and
mathematics to
improve investigations
.
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Serology
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 labs. However, with
limited funds and the time required for DNA testing,
most labs still use many of the basic serology testing
procedures.
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Blood Characteristics
Chapter 10
.
Plasma is the fluid portion of the
blood (55%)
Cells (45%)
Erythrocytes are red blood
cells. They are responsible for
oxygen distribution.
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
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Unknown Stain at a Scene
Questions to be answered:
Is it blood?
Is it human blood?
Whose blood is it?
Determine blood type, alcohol
content, drugs present
Determine the method(s) in
which blood may have been
deposited
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Presumptive Tests for
Blood Determination
Presumptive tests are sensitive but not specific
Phenolphthalein 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/TMB—reacts with the heme
group in blood causing a blue-green color
Luminol test—reaction with blood to produce light
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CHEMILUMINESCENCE
Luminol is oxidized by peroxide. The product is in
an excited state. It releases energy as a photon which
we see as a blue glow.
The iron in hemoglobin catalyzes the
reaction…makes it happen much more quickly
without being consumed in the reaction.
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Luminol
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Other presumptive tests
Other presumptive tests work on the same
principle
Instead of a blue glow, a colorless
compound turns a vivid color
All presumptive tests are sensitive,
relatively inexpensive, and quick, but not
specific
Presumptive tests are good for screening
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Animal/Human Blood
Animal: Larger nucleic red
blood cells
Human: smaller cells, red (no
nuclei), white (large), platelets
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Human vs. Animal Blood
Microscopic observation
Precipitin test—is based on the reaction of an
antibody specific to human blood with antigens in
the blood. Human 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 antiserum will react
with human proteins, if human blood is present.
This test is very sensitive and requires only a
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Precipitin Test
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Inject rabbit with human
proteins
Rabbit’s immune system
makes antibodies to fight
foreign proteins
Rabbit’s serum is collected
and used to test questioned
blood
It will react with human
protein.
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Historical Perspective
of Blood Typing
Around 1900, Karl Landsteiner discovered that there are
four different types of human blood based on the
presence or absence of specific antigens found on the
surface of the red blood cells.
In 1940, Landsteiner and Weiner reported the discovery
of the Rh factor by studying the blood of the Rhesus
monkey. 85% of Caucasians, 94% of Black Americans
and 99% of all Asians are Rh positive.
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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
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Blood Typing
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
type A, B, AB, or O blood.
Blood type O has neither antigen A or B and
will agglutinate with A, B, or AB blood
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Blood Groups
Antibody Can Give
Can Get
Blood From
Type
Antigen
A
A
B
A, AB
O, A
B
B
A
B, AB
O,B
AB
A and B
Neither
A nor B
AB
A, B, O, AB
O
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Blood To
Neither
A and B A, B, O, AB
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O
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Population Distribution
of Blood Types in the U.S.
Type
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Percent
O
45
A
40
B
11
AB
4
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Secretors
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.
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Rh Factor
Another antigen found in the blood of
about 85% of the human population
Also found in the rhesus monkey
An Rh negative mother can develop
antibodies against her Rh positive fetus.
Not a modern problem because the body’s
immune system is easily tricked to prevent
this and help ensure future healthy babies.
Blood Typing Game
http://nobelprize.org/educational_games/medi
cine/landsteiner/readmore.html
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Other Uses of Immune Reactions
Principle:
Uses an immune reaction [Antigen – Antibody
reaction] to estimate many substances
This is extension and application of the
concept ...the substances tested are not
always “antigens.” They are substances for
which scientists created “antibodies.”
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Immunoassays tagged with
radioactivity
Ag : substance to be measured
Ag* radiolactively taagged substance]
Ag + Ag* + Ab AgAb + Ag*Ab + Ag + Ab*
Unbound Ag* and Ag washed out
Radioactivity/enzyme activity of bound residue
measured
Substance concentration is inversely related to
radioactivity
Advantages
Highly specific: Immune reactions are specific
High sensitivity : Immune reactions are sensitive
Disadvantages
Radiation hazards: Uses radioactively-tagged reagents
Requires specially trained persons
Labs require special license to handle radioactive
material
Requires special arrangements for
Requisition, storage of radioactive material
radioactive waste disposal.
Enzyme Linked Immunosorbent
Assay
Principle:
Uses an immune reaction like RIA
Differs from RIA in detection method
Detection based on
Enzyme catalysed reaction OR
Fluorescent probe
NOT radioactivity [great advantage!]
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Advantages
Sensitive: nanogram levels or lower
Reproducible
Minimal reagents
Qualitative & Quantitative
Qualitative HIV testing
quantitative assays Ther. Drug Monitoring
Greater scope
Suitable for automation high speed
NO radiation hazards
Applications of Immunoassays
Analysis of hormones, vitamins,
metabolites, diagnostic markers
ACTH, FSH, T3, T4, Glucagon, Insulin,
Testosterone, vitamin B12, prostaglandins
Therapeutic drug monitoring:
Barbiturates, morphine, digoxin, asthma
medications
Diagnostic procedures for detecting
infection
HIV, Hepatitis A, B etc
Enzyme markers
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Other “stuff” that can be typed
from blood and body fluids
Polymorphic (many forms) Enzymes
– Phosphoglucomutase
• PGM1 - 58%
• PGM2 – 6%
• PGM2-1 – 36%
– Adenosine deaminase
– Haptoglobin
– Transferrin
– And many more
In the “good old days”…
Labs tested up to 10 substances in body
fluids and used product rule to determine
stats.
Results were often limited…1/100-1,000
Sometimes better, my profile came up to
1/1,000,000!
And that’s as good as it got until DNA
Now stats are up to the 1 in billions,
trillions, quadrillions
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Use Probability Rule to Calculate
Statistics
If a person has ABO type O blood and PGM enzyme 2-1
(and they are inherited independently):
Type O 45%
Type PGM 2-1 36%
Use the PRODUCT RULE
of having both is product of the two.
(45/100 x 36/100) x 100% =
16.2% of the population has both
Test different enzymes and keep multiplying percentages
to narrow the field
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Serology
Find body fluid stains
Identify them
Characterize them by
genetic markers
Select and prepare
samples for DNA
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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.
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Blood Spatter Evidence
A field of forensic investigation which deals
with the physical properties of blood 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.
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BLOODSPATTER 101
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Blood Pattern Reconstruction
Lab Results
Reconstruction
Scene Pattern
Reconstruction
1. Genetic marker typing
1. Stain condition
2. Age of stain
determination
2. Pattern
3. Location
3. Source determination
4. Race determination
(limited)
5. Sex determination
—From “Cracking Cases” by Dr. Henry C. Lee
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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?
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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.
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Conditions Affecting
Shape of Blood Droplet
Size of the droplet
Angle of impact
Velocity at which the blood droplet left its origin
Height
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
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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 bloodshed
The position of the victim and/or object during bloodshed
Movement of the victim and/or object after bloodshed
Sequence of events
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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
Back spatter—blood that is directed back toward
the source of energy
Cast-off—blood that is thrown from an object in
motion
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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
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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
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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
strings.
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Bloodstain Patterns
The shape of a blood drop:
Round—if it falls straight down at a 90 degree
angle.
Elliptical—blood droplets elongate as the angle
decreases from 90 to 0 degrees; the angle can
be determined by the following formula:
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sin q = opp/hyp =w/l
So:
inverse sin or arc sin
of w/l = angle
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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
travel.
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Impact
The more acute the angle of
impact, the more elongated the
stain.
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.
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w/l =.56/1.17=.4786
Arc sin .4786=29 0
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Point of Origin
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People of Historical Significance
Paul Kirk (1902-1970) was a professor of
criminalistics and biochemistry at Berkeley in
California. He actively assisted law enforcement
organizations from 1935 to 1967. His book, Crime
Investigations, contained a chapter in which he
discussed the application of blood stain pattern
analysis to criminal investigations. Dr. Kirk analyzed
the blood stain pattern photos from the Sam
Sheppard case and was instrumental in Sheppard’s
release at his second trial. Find out more about the
case at Courttv’s crime library.
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People in the News
Herbert L. MacDonell is considered by many as the
father of modern bloodstain pattern analysis. He is the
director of the Lab of Forensic Science and founder of
the Bloodstain Evidence Institute (1973) in Corning,
NY. His work, Bloodstain Pattern Interpretation,
helped to jump start this discipline. He has consulted
on criminal cases in all 50 states, in addition to
testifying in the O.J. Simpson trial and in the
assassination cases of Sen. Robert F. Kennedy and
Dr. Martin Luther King Jr.
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More about Serology
For additional information about blood
evidence, and famous crimes that involves
serology, check out Court TV’s Crime
Library at:
www.crimelibrary.com/criminal_mind/forensics/serology/1.html
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