Blood and Blood Spatter

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Blood and Blood Spatter
Serology
Blood Spatter Analysis
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Serology
What is serology?
Serology is the study of serums.

• Examples
• Blood
• Saliva
• Sweat
• Etc.

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Ludwig Tessnow Case
Germany 1901.
Ludwig Tessnow was accused of murdering two
children. He claimed red stains on his clothes
were wood dyes.
Paul Uhlenhuth discovered how to test for blood
and to distinguish between human and animal blood.

• Tessnows clothes were tested. The results
  showed the stains were not dyes, but blood. As a
  result Ludwig was convicted of murder and
  executed in 1904.

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Blood Typing
In 1901 Karl Landsteiner discovered the human
blood groups.
The difference in blood groups are due to the
presence or absence of certain protein molecules
called antigens and antibodies.
Blood Type Antigen Antibody
A A B 42
B B A 10
AB A B None 4
O None A B 44
Landsteiner broke the groups into the familiar A,
B, AB, and O.
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Blood Typing
Besides A, B, AB, and O there are over 100 blood
factors that can be used to identify a person.
Example RH factor
Until the 1990s scientists used these factors to
identify someone.

• Today we use

DNA
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How much blood do we have?

• You have about 10 pints of blood pumping through
  your body.
• Plasma is the liquid portion of blood and it is
  55 of the blood volume.
• Red blood cells transport oxygen from the lungs
  and carbon dioxide to the lungs for removal.
• Antigens on the surface of the RBC give them
  their blood characteristics.
• White blood cells produce antibodies to disable
  and/or destroy invaders.
• Platelets help to clot blood. The protein fribrin
  catches red blood cells.

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Secretors
What is a secretor?
A secretor is defined as a person who secretes
their blood type antigens into body fluids and
secretions like the saliva in your mouth, sweat,
etc.

• As a general rule, in the U.S. 80 of the
  population are classified as secretors.

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Blood at the Crime Scene
Is it blood?
We use presumptive tests to answer this question.
Hemastix reacts with the hemoglobin in blood.

• Hemastix will turn from yellow to dark green if
  blood is present.

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Blood at the Crime Scene

• Presumptive Tests (continued)
• Kastle-Meyer Test
• A drop of phenolphthalin reagent is added to the
  sample, and after a few seconds, a drop of
  hydrogen peroxide is applied to the swab. If the
  swab turns pink rapidly, it is said to test
  presumptive positive for blood.

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Blood at the Crime Scene
Presumptive Tests (continued)
Luminol reacts with iron present in blood and a
chemical reaction that leads to luminescence
revealing the location of the blood.
Picks up blood even if diluted up to 10,000 times.
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Blood at the Crime Scene
From what species?
Precipitin or Gel Diffusion Blood from mummies
4,000 5,000 years old still give positive
results!
If its human blood, whose is it?

• ABO Testing
• DNA Fingerprinting

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Interpreting Blood Spatter

• Blood spatter can tell us the following
• Direction blood droplet was moving
• Where the blood droplet came from (area of
  origin)
• Type of weapon used in the crime (number or
  blows)
• Position of victim, suspects, and objects
• Sequence of events

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Interpreting Blood Spatter
How to tell the direction that blood droplet was
moving.
Here is a picture of some blood spatter which hit
a surface.

• The pointed part of the blood spatter give you
  the direction the blood was traveling at the
  point of impact.

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Interpreting Blood Spatter

• Working with multiple droplets can tell where the
  victim was located when the crime was committed.

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Angle of Impact

• The angle of impact is useful in determining
  where blood spatter originated from.
• To find the angle of impact
• Sin (angle) Width / Length

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Types of Blood Spatter
Passive blood spatter is created by the force of
gravity.
Height determines diameter of blood spatter.

• Irregular spatter pattern indicate higher fall.

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Types of Blood Spatter

• Projected blood spatter occurs when energy has
  been transferred to the blood source. The higher
  the velocity, the smaller the drops
• Low, Medium High Velocity
• Falling blood drops
• Gunshot wounds
• Arterial Spurting
• Cutting of an artery
• Expiratory
• Blood from mouth or nose

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Types of Blood Spatter

• Contact or Transfer blood spatter occurs when an
  object with blood on it comes into contact with
  other objects.
• Wipe
• Swipe

Surfaces and weapons can affect the blood
spatter, therefore, testing of different
variables is often done in a case.