1. YouTube - The Sam Sheppard case
Forensic Serology
YouTube - The Sam Sheppard case

2. Introduction
1901- Karl Landsteiner recognized that human blood was distinguishable by its group or type
Bloodstains are often found at crime scenes (homicides, assaults, rapes, etc.)
Blood Factors (like A-B-O, Rh factor, and others) have been used to link a crime to a suspect or a victim.
Since the early 1990’s, DNA technology has completely changed the way in which bloodstains and other biological evidence is individualized.

3. The Nature of Blood Blood is composed of :
Plasma- the fluid portion of unclotted blood
Red Blood Cells (erythrocytes)
White blood cells (leukocytes)
Platelets
Serum-yellowish liquid that separates from blood when a clot has formed.

4. Antigens and Antibodies
Antigens-substances, usually proteins, found on the surface of red blood cells that give the cells specific characteristics
Antibodies-proteins found in blood serum that destroy or inactivate a specific antigen by binding to it.
Agglutination-clumping together of red blood cells cause by an antigen/antibody interaction
Serology-the study of antigen-antibody reactions

5. Blood Typing Serology – the study of antigen-antibody reactions.
Distribution of blood types in the U.S.: O A B AB
43%
42 %
12 %
3 %

6. Neither anti-A nor Anti-B
Blood Types
Blood Type
Antigens on Red Blood Cells
Antibodies in Serum A
Anti-B B
Anti-A AB
Neither anti-A nor Anti-B O
Neither A nor B
Both anti-A and Anti-B

7. Forensic Characterization of Bloodstains
Bloodstains must be analyzed to determine:
Is it blood?
From what species did the blood originate?
How closely can it be associated with a particular individual?

8. Forensic Characterization of Bloodstains
Color Tests-Kastle-Meyer test-oxidation of hemoglobin in blood produces a deep pink color.
Luminol-reaction with blood produces light; faint blue glow known as luminescence; very sensitive technique
Immunoassays-Antigen-antibody reactions are used to identify blood and also detect drugs in blood

9. Forensic Characterization of Bloodstains
Microcyrstalline tests-Takayama and Teichmann tests; substances form crystals when they come in contact with hemoglobin; less sensitive than color tests
Precipitin test-used to detect human blood
Gel diffusion-another method for detecting human blood.