1. SEROLOGY Science involving the identification & characterization of
blood, semen, and other body fluids usually found in dried
form on items of physical evidence

2. Topics in This Unit What is blood? Blood typing
Determining presence of blood
Blood spatter

3. The Functions of Blood Blood functions include:
Transport of cells and compounds
Regulate pH and electrolytes of interstitial fluids
Limit blood loss through damaged vessels
Defend against pathogens, toxins
Absorb, distribute heat as part of temperature regulation
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4. The Nature of blood Adult human has 4-6 liters; transports oxygen
Plasma: 55% of blood; fluid part made mostly of water
Red Blood Cells: contain hemoglobin
White Blood Cells: fight infection; used in DNA testing
Platelets: essential for clotting

5. The Composition of Whole Blood
Figure 11-1(c)

6. The Composition of Blood
Blood Collection and Analysis
Whole blood can be fractionated into:
Plasma (liquid component)
Formed elements (cellular components)
Red blood cells (RBCs)
White blood cells (WBCs)
Platelets
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7. Formed Elements Red Blood Cells Also called, erythrocytes or RBCs
Make up about 45% of whole blood volume
Make up 99.9% of the formed elements
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8. Formed Elements
Key Note
Red blood cells (RBCs) are the most numerous cells in the body. They circulate for about four months before being recycled; millions are produced each second. The hemoglobin inside transports oxygen from the lungs to peripheral tissues and carbon dioxide from the tissues to the lungs.
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9. BACKGROUND
ABO blood typing: Karl Landsteiner looking for way to make blood
transfusions more successful
not used forensically until 1915
MNS System of typing: M - 30% of population
N - 22%
S - 48%
Rh factor: Alexander Weiner
work with Rhesus monkeys
also called D antigen
+ 85% of population
- 15%
Other Systems: > 100 different blood factors ---> 15 different systems
theoretically: can individualize by identifying all factors
realistically: some factors are destroyed as blood dries

10. Blood Type
Determined by presence or absence of specific antigens (agglutinogens) on outside surface of RBC
Antigens are called A, B, and Rh
Antibodies (agglutinins) in plasma react with foreign antigens on RBCs
RBCs clump and break open
Anti-Rh antibody made after exposure to Rh-positive blood cells
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11. Blood Types and Cross-Reactions
Figure 11-7(a)

12. Surface antigens Figure 11-7(b) 2 of 5
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13. + + Surface antigens Opposing antibodies Figure 11-7(b) 3 of 5
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14. + + Surface antigens Opposing antibodies Agglutination (clumping)
Figure 11-7(b)
4 of 5
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15. Agglutination (clumping) and hemolysis+
Surface
antigens
Opposing
antibodies +
Agglutination (clumping) and hemolysis
Figure 11-7(b)
5 of 5
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16. Genetics of ABO Blood Type
Human blood type is determined by co-dominant alleles.
There are three different alleles for human blood type:
Blood types
For simplicity, we call these IA A IB B i O

17. Blood types of offspring
ABO Genotypes
Each of us has two ABO blood type alleles, because we each inherit one blood type allele from our biological mother and one from our biological father. A description of the pair of alleles in our DNA is called the genotype.
Allele from Parent 1
Allele from Parent 2
Genotype of offspring
Blood types of offspring IA
IA IA A IB
IA IB AB i
IA i
IBIB B
IBi ii O

18. At the crime scene Searching the scene: does the suspect have a wound?
did the suspect attempt to clean up?
Preservation and Collection: time is a factor
preserve in dry state; use paper bags/envelopes; scrape dried stains

19. Basic questions for lab analysis
Is it blood?
Use Presumptive/Screening color tests: test for hemoglobin
A. Kastle-Meyer: phenolphthalein and H2O2
some vegetables test positive
color change to deep pink color

20. Hematest tablet/hemastix strip: color change to green
Luminol: results in production of light
can detect bloodstains diluted up to 10,000X
use in darkened room; luminesces iron oxides of blood
false positive with bronze, brass, Cu, some vegetables

21. Is it HUMAN blood?
Precipitin test: human antiserum obtained by injecting rabbits
WHOSE blood is it? How closely associated to a particular individual?
Use blood typing/ Use DNA
Typing: based on rxns between antigen(found on surface of RBC)
and antibody(found in plasma/serum)
% Type Antigens Antibodies Can Give To Can Receive
A A anti-B A, AB O, A
B B anti-A B, AB O, B
AB A, B none AB O, A, B, AB
43 O none both O, A, B, AB O

22. Secretors: 80% of population
antigens of ABO system found
in high concentration in most body
fluids - saliva, semen, gastric
juice, vaginal secretions, sweat
Probability
Example 1: AB, +, M
3/100 X 85/100 X 30/100 = 7650/1,000, of 131
Example 2: B, -, N
12/100 X 15/100 X 22/100 = 3960/1,000, of 253

23. Blood typing
Positive test results in coagulation
between antigen and antibody

24. How, why, when did the fluids get deposited on items associated with
the scene?
NOTE: see handout
Other questions:
Determine alcohol content of the blood
Determine drugs present in the blood