FORENSIC SCIENCE Serology

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FORENSIC SCIENCESerology
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What is Serology?

• Serology is the study of serums such as blood,
  saliva, semen and sweat.
• A forensic serologist applies this information to
  criminal activity and the law.

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What is Blood?

• Blood is a very complex mixture of cells,
  enzymes, proteins and inorganic substances.
• The fluid portion is the plasma.
• Solids are suspended in the plasma.

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Characteristics of Blood

• Blood plasma is made primarily of water and
  accounts for 55 of the total amount of blood
  content.
• Three different types of cells are suspended in
  the plasma. These cells are
• Erythrocytes are the red blood cells and are
  responsible for carrying oxygen.
• Leukocytes are the white blood cells and are
  responsible for cleaning the system of foreign
  invaders.
• Thrombocytes are the platelets and are
  responsible for blood clotting.
• Blood serum is the liquid that separates from the
  blood when a clot is formed.

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Blood Questions

• When blood is found at a crime scene, several
  questions must be answered
• 1. Is it blood?
• 2. If so, is it human or animal?
• 3. If human, what type of blood is it?
• 4. How did the blood fall or spatter?

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1st Question Is it blood?

• A crime scene investigator cannot presume that
  every red stain or liquid is blood.
• Ketchup, spaghetti sauce and red jello may all be
  mistaken for blood.
• The investigator will perform presumptive tests
  at the scene to determine if the substance is
  blood.

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The Presumptive Blood Tests

• Two of the common Presumptive Tests are color
  tests.
• Kastle-Meyer -phenolophthalein and hydrogen
  peroxide are mixed together and the bloods
  hemoglobin will cause the formation of a deep
  pink color. Several household items will yield a
  false positive for a color test. For example,
  potatoes and horseradish yield a false positive.
  However, since these are unusual in a crime scene
  setting the Kastle-Meyer is a reasonable
  indication of blood.

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The Presumptive Blood Tests

• 2. Hemastix the strip is moistened with
  distilled water and then dipped into the
  substance. A green color indicates blood.
• A third option is luminol.
• 3. Luminol reacts with blood to produce light
  instead of color. Luminol detects blood even if
  the area has been cleaned.

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It is blood, but is it human blood?

• At the lab, the technician will need to determine
  if the blood is human or animal.
• First, the technician will complete a microscopic
  examination.
• The red blood cells of mammals do not have a
  nucleus. This is an important distinction.

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Non-Mammalian Animal Blood

• Frog Blood
• Larger nucleic red blood cells that undergo cell
  division
• No platelets

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Human Blood

• Numerous non-nucleic red blood cells--5 to 6
  million per mm3
• Larger but less numerous white blood cells 5 to
  10,000 per mm3
• Tiny, cellular fragments 350 to 500,00 per mm3
  called platelets

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It is blood, but is it human blood?

• The next test that the technician will conduct is
  the precipitin test.
• In this test, the blood is injected into a
  rabbit antibodies are formed rabbits blood is
  extracted as an antiserum the antiserum is
  placed on sample blood. It will negatively react
  with human proteins.
• This test is very sensitive and requires only a
  small amount of blood.

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It is human blood, but what type?

• Around 1900, Karl Landsteiner discovered that
  there are four different kinds 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 Type Terminology

• ABO blood groups--based on having an A, B, both
  or none of the factors on the red blood cell
• Rh factor--may be present on the red blood cell
  positive if present and negative if not
• Antigen--a substance found on a red blood cell
• 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 Genetic Terminology

• Genotype--letters that represent the traits ie,
  AA, AO, BO, BB, AB and OO
• Phenotype--words that describe the traits
• Heterozygous--different alleles for the same
  trait ie AO, BO, AB
• Homozygous--the same alleles for the trait ie
  AA, BB, OO

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Blood Typing

• A blood type has antigen A and will agglutinate
  with B.
• B blood type has antigen B and will agglutinate
  with A.
• AB blood type has antigen A and B and will not
  agglutinate with either A or B.
• O blood type has neither antigen A or B and will
  agglutinate with either.

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Blood Reactions to Antiserum
REACTION
Anti-A Serum
Anti-B Serum
BLOOD TYPE
No agglutination Agglutination Agglutination No
agglutination
Agglutination No agglutination Agglutination No
agglutination
Type A Type B Type AB Type O
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Blood Typing
Reactions to Anti-Serum
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Blood Groups
Only certain blood types can donate or receive
blood from other blood types. If the wrong blood
is transfused, the person may die.
Can Give Blood To
Can Get Blood From
Type
Antigen
Antibody
A
A
B
A, AB
O, A
B, AB
O , B
B
B
A
Neither A nor B
AB
A and B
AB
A, B, O, AB
Neither A nor B
A, B, O, AB
O
A and B
O
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Population Distribution of Blood Types in the U.
S.
Type
Percent
O
45
A
39
B
12
AB
4
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Typing of Dried Blood Stains

• Absorption-elution technique
• Antiserum is placed on the blood stain.
  Antibodies combine with the specific antigens.
• Unreacted serum is washed off the bloodstain.
• Stained material is heated to 56 degrees C,
  breaking the antibody-antigen bond. This process
  is known as elution.
• Known red blood cells are added. Agglutination
  will occur if antigens present on the added RBCs
  were also originally on the stained material.

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Differentiating Within Blood Types

• The determination that the blood type is O
  eliminates 55 of the population. In order to
  narrow down the possibilities within a specific
  blood type, the blood is tested for certain
  enzymes.
• Enzymes are proteins that speed up or slow down
  chemical reactions. Enzymes that exist in
  different forms are called polymorphic and can be
  broken down into their separate proteins called
  iso-enzymes.

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Commonly Used Blood Enzymes and Proteins

• Adenosine deaminase AD
• Adenylate kinase AK
• Carbonic anhydrase II CA II
• Erythrocyte acid phosphatase EAP
• Esterase D EsD
• Glucose-6-Phosphate dehydrogenase G6PD
• Glyoxylase U GLO I
• Group-specific component Ge
• Haptoglobin Hp
• Peptidase A Pep A
• Phosphoglucomutase PGM
• 6-Phosphogluconate dehydrogenase 6PGD
• Transferrin Tf

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• PGM--phenotypes
• Electrophoresis can separate the protein
  components into these 10 iso-enzymes.

-

1- 1 2- 2 2-1- 21- 2-1
21 22- 11-
Three of these are most common PGM 1, PGM 2-1
and PGM 2
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• EAP--phenotypes
• Determined by the intensity of the fluorescence.
  The darker the band the more it fluoresced.

B C A
A BA B
CB C CA
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The final question, how did the blood fall or
spatter?

• A group of blood spatter specialists deal with
  the physical properties of blood and the patterns
  produced under different conditions as a result
  of various forces being applied to the blood.

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The final question, how did the blood fall or
spatter?

• Blood, as a fluid, follows the laws of physics.
  It is not influenced nor affected by race,
  gender, or age of the one bleeding.

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BLOOD DROPLETCharacteristics

• A blood droplet will remain spherical in space
  until it drops onto 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.

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BLOOD DROPLETVolume

• Is approximately 0.05 cc
• Is not the same for all blood droplets--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 EFFECTINGBLOODSTAIN SHAPE

• Height of the droplet
• Size of the droplet
• Angle of impact
• Velocity at which the blood droplet left the
  original surface
• 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 at the time of blood shed
• 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.

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Questions Answered by Blood Spatter
Interpretation

• 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

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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.
• Backspatter--blood that is directed back toward
  its source of energy.
• Cast-off--blood that is thrown from an object in
  motion

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Bloodstain Terminology

• Contact stain--general term referring to
  bloodstains caused by contact between a wet,
  blood-bearing surface and a second surface which
  may or may not have blood on it
• Transfer--image is recognizable and may be
  identifiable with a particular object
• Swipe--wet blood is transferred to a surface
  which did not first 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 feet/second.
• High velocity--greater than 100 feet/second
  gives a fine mist appearance
• Low velocity--5 feet/second or less
• Medium velocity--5 to 25 feet/second.

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Bloodstain Pattern

• Terminal Velocity
• Directionality
• Angle of Impact

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Blood Stain Patterns

• The shape of a blood stain
• Round--if it falls straight down at a 90 degree
  angle.
• Elliptical--Blood droplet elongates as the angle
  decreases from 90 to 0 degrees. The angle can be
  determined by the following formula
• width sine of the impact angle
• length

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IMPACT

• The more acute the angle of impact, the more
  elongated the stain.
• 90 degree angles are perfectly round 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.
• The greater the height the drop falls the larger
  the spatter.

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Height of the Droplet and Spatter Size
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Angle of Impact and Spatter Shape
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Blood Stains

• 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 the stain is traveling.

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Area of Intersection

• The location of the blood source can be
  determined by drawing lines the various blood
  droplets to the point where they intersect. This
  is the bloods origin.

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Area of Convergence

• The area of convergence is the point of origin
  the spot where the blow occurred.
• It is determined by drawing a line from the
  area of intersection straight up to where to
  where the angle of impact would intersect

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CRIME SCENE
What evidence can you see in this crime scene?
What story does the scene tell?
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Bring In The Dogs!
The dog locates human scent. A closer look shows
that the ashes have human remains and clothing.
In addition, look closely at the rocks on the
next slide.
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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
  stains, height of the perpetrator, position of
  the victim, left/right hand, whether the body was
  moved, etc.

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Another Body Fluid - Sperm

• Among the smallest and most highly specialized
  cells in the human body.
• Has a head and a tail
• Contains 23 chromosomes with the genetic material
  found in the head
• Males release 2.5 to 6 milliliters of seminal
  fluid per ejaculation with approximately 100
  million sperm per milliliter.

Magnified 400X
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Semen

• Determination of Seminal Fluid
• - Suspect stain may have stiff, crusty
  appearance
• - Acid phosphatase color test- presumptive
  test
• the presence of acid phosphatase, the enzyme
  secreted by the prostate gland into the seminal
  fluid, will turn purple when sodium alpha
  naphthylphosphate and Fast Blue B solution are
  placed on it.
• It will also fluoresce under UV light when it
  comes in contact with 4-methyl umbelliferyl
  phosphate.

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Detection and Collection of Semen Sample
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Semen (cont.)

• Determination of Seminal Fluid
• Prostate Specific Antigen (PSA) or P30--unique to
  seminal plasma
• P30 is isolated and injected into a rabbit where
  antibodies are produced (anti-P30)
• The stain extract is placed in one well of an
  electrophoresis plate and the anti-P30 in the
  opposite well. The electric is applied and the
  antigens and antibodies move toward each other.
  The formation of a precipitation line between the
  wells shows the presence of P30 in the sample
  stain. It must be seminal fluid.

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Microscopic Examination of Sperm

• A microscopic examination will also determine if
  the sample is semen
• The presence of spermatozoa confirms that the
  sample is semen

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No spermatozoa?

• The male could have oligospermia a low sperm
  count
• The male could have aspermia no sperm due to a
  vasectomy

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Collection of Rape Evidence

• The Medical Examination Collection of Physical
  EvidenceThe following types of physical evidence
  should be collected during the medical
  examination for laboratory analysis
• HAIR (both pubic and head hair)
• Cannot individually identify a person unless the
  root is present
• Does provide strong collaborative evidence
  individual was at the crime scene
• Can be distinguished between human and animal
• May be able to determine race and
• May be able to establish the part of the body
  from which the hair came.

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Collection of Rape Evidence (cont)

• FIBERS
• Limited value due to mass production of clothing
  and
• In rare cases, can be used to deduce individual
  identification with a high degree of certainty.
• BLOOD
• Can be distinguished as to human or animal and
• DNA analysis can provide individual
  identification.
• FINGERNAIL SCRAPINGS
• Used to collect DNA evidence for individual
  analysis and identification.
• VAGINAL, RECTAL AND ORAL SWABS AND SMEAR
• Used to collect DNA evidence for individual
  analysis and identification

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Secretors

• 80 of people are considered secretors. Their
  blood-type antigens are found in high
  concentration in their body fluids such as
  saliva, semen, vaginal secretions and gastric
  juice. If you are a secretor, you will have a
  higher concentration of A and B antigens than
  does your blood!!
• With the advent of DNA, the secretor evidence is
  not as important as it once was.