1. Study of bodily fluids using antigen-antibody reactions
Serology
Study of bodily fluids using antigen-antibody reactions

2. Blood Components RBC – Erythrocytes WBC – Leukocytes
Platelets – Contains fibrin which clots blood
Plasma – Fluid portion of the un-clotted blood
Serum – Fluid that is separated from clotted blood

4. Antigen – Antibody Reactions
Antigens- proteins on surface of cells
Antibodies- proteins that are produced in response to the presence of foreign antigens (Found in the serum of blood)
Agglutination- reaction that occurs when specific antibodies attach to antigen sites and cause RBC to clump together
>15 blood antigen systems have been identified, including A-B-O and Rh systems
( Saferstein, 2004, pg 330)

5. What Makes Blood Different?

6. Agglutination

7. ABO System Blood Type Antigens/RBC Antibodies/Serum A Anti-B B Anti-A
Neither anti-A or B O
Neither A nor B
Both anti-A and B

8. Blood Typing Anti-A serum + blood Anti-B Serum + blood Antigen Present
Blood Type + _

9. Immunoassay Techniques
Antigen-Antibody reactions used for the detection of Drugs in blood, urine and semen
EMIT : Enzyme-Multiplied Immunoassay Technique – are not totally specific
Monoclonal Antibody Tests: antibodies are produced to react to ONE specific antigen
Currently found in newest forensic test kits (pg )

11. Standard Analysis of Blood
Questions about crime scene blood:
Is the substance blood?
Is the blood human?
Can the blood be associated with a particular individual?

12. Is the substance blood? Kastle-Meyer Color Test
Phenolphthalein, hydrogen peroxide, and suspected blood stain are mixed; positive reaction indicated by a deep pink color
Based upon observation that hemoglobin possesses peroxidase activity
This test is a presumptive or preliminary test for blood.
Substances other than blood may produce false positive results (pg 336)

13. Is the substance blood? Con’t
Hemastix Color Test
Hemastix—has been found to be very useful by field investigators—a dipstick moistened with distilled water is placed in contact with the suspect blood—a green color change indicates a positive result (pg 336)

14. Is the substance blood? Con’t
Luminol Test
A test that produces light when it reacts with blood rather than color
Large areas can be quickly screened for blood, by spraying luminol reagent
“Luminol test is extremely sensitive—it is capable of detecting blood stains that have been diluted up to 300,000 times.”
Does not interfere with subsequent DNA testing! (pgs )

15. Is the blood human? Precipitin Test
If you inject an animal with human blood, the animal will create antibodies that can then be recovered and used to test for various human antigens including human blood antigens
The recovered antibodies are called human antiserum
To test for human blood, human antiserum and an unknown blood are put together—if the blood is human a precipitate will form.
(p338)

16. Can the blood be associated with a particular individual?
A-B-O types and enzymes
Used until the mid 1990’s, characterization of bloodstains included determining A-B-O types and polymorphic enzyme markers such as PGM (phosphoglucomutase)
These tests added statistical information with which to reduce the number of possible sources of the bloodstain
Because antigens, and enzymes occur independently of one another, the probability of a dried blood stain having a particular combination of these factors is determined by the product of their distribution in the population (pg 339)

17. Can the blood be associated with a particular individual? Con’t
Statistical Example:
Blood stain found to be of type A— corresponds to 42% percent of population
Stain contains PGM-1—corresponds to 58% of population
The combined effect of just these two factors, using the product rule is 42% x 58% or 24 %
Clearly the more factors, the smaller the frequency of occurrence in the population

18. Can the blood be associated with a particular individual? Cont….
DNA Analysis
Since the 1990’s DNA analysis has replaced forensic reliance on blood factors for the routine characterization of bloodstains
DNA analysis gives extremely accurate individualization results.

19. Stain Patterns of Blood
The location, distribution and appearance of bloodstains and spatters can be used to interpret and reconstruct the events that must have occurred to produce the bleeding. (pg. 342)

20. Stain Pattern Analysis General Conclusions
Surface texture: The harder and less porous the surface, the less spatter results.
Direction of Travel: The direction of travel of blood can be discerned by the stain’s shape — the pointed end always faces its direction of travel (pg 342)

21. Stain Pattern Analysis General Conclusions Cont…
Impact Angle: A drop of blood striking a surface at a right angle gives rise to a nearly circular stain; as the angle decreases, the stain becomes more elongated in shape
Origin of Blood Spatter: Can be determined by establishing lines through the long axis of several individual blood stains. The intersection of the lines represents the point from which the blood emanated. (pg 342)

22. Principles of Heredity
The gene is the basic unit of heredity. They found on chromosomes. All human cells contain 46 chromosomes (23 pairs). Only exception: reproductive cells
During fertilization, a sperm and egg combine so each contributes chromosomes to form the new cell (zygote)

23. Principles of Heredity Cont..
Inheritance Rules
A gene pair of two similar genes—is homozygous—no problem determining a person’s outward characteristics
A gene pair of two different genes—is heterozygous—one gene is dominant, the other recessive—person’s outward characteristics depend on the dominant gene

24. Paternity Testing
Many cases of disputed paternity can be resolved when suspected parents and offspring are related according to their blood group systems
Type O blood is considered a recessive gene so……

25. Paternity Example O O A AO AO B BO BO Father’s Genotype Mother’s
If the Child in question is type AB would the suspect father be cleared?

26. Paternity Testing Con’t
Routine paternity testing involves characterizing many blood factors other than A-B-O. Using these other factors the probability of establishing paternity becomes better than 90%. Once DNA analysis is done the odds become better than 99%. (pg 348)

27. Forensic Characterization of Semen
A large number of cases involve sexual offenses, making it necessary to examine exhibits for the presence of seminal stains.
The forensic examination of semen is a two-step process:
Semen must be located
Tests must be performed to prove its identity—it may even be tested for blood type
Note: Semen is checked for blood type because many individuals are secretors

28. Secretors 80% of individuals are classified as secretors
This means that their blood-type antigens are also found in high concentrations in most body fluids
Ex- Saliva, semen, vaginal secretions, and gastric juices
**Saliva & semen have higher concentrations of A & B antigens than blood!!

29. Semen Location and Identification
There are two methods of locating semen:
Semen is often readily visible on a fabric because it has a stiff crusty appearance- unreliable
The acid phosphatase color test can locate and at the same time identify semen.

30. Acid Phosphatase Color Test
Acid phosphatase is an enzyme secreted by the prostate gland into seminal fluid that is in far greater concentrations than those found in any other body fluids.
Its presence can be detected using different tests:
1. Contact with a special acidic solution and Fast Blue B dye shows a purple change
2. Contact with a solution of MUP fluoresces under UV light. (p.349)

31. Acid Phosphatase Test, Con’t
Large areas or fabrics can be quickly searched by moistening filter paper with the detector solutions and rubbing over the suspect area
Some substances will give a false-positive result (fruit juice, contraceptive creams, etc), but none of these substances will react with the speed of seminal fluid.
Note: A reaction of less than 30 seconds is a strong indication of semen. (p 349)

32. Microscopic Examination of Semen
Rapid stirring of a fabric-stain-water mixture will transfer a small amount of sperm into the water. A drop is then taken, dried, stained and looked at under the microscope.
The presence of sperm indicates the presence of semen.

33. Microscopic Problems
Locating sperm with the microscope is not that easy for three reasons:
1. Sperm are very brittle when dried and easily disintegrate. They are also hard to remove from cloth material.
2. Sexual crimes may involve males who have an abnormally low sperm count, condition called oligospermia.
3. Males who have no sperm in their seminal fluid, condition called aspermia—often due to increasing numbers of vasectomies.

34. Detecting Semen, Cont…
A positive result for acid phosphatase and a negative result for semen give ambiguous results—In this case, p-30 or Prostate Specific Antigen (PSA) is used to detect seminal plasma – Immunoassay tests

35. p30 Prostate Specific Antigen Test
Formation of a visible line between the wells of anti p-30 and semen extract–proves the stain is seminal

36. Collection of Rape Evidence Victim
Outer and undergarments are placed in separate paper bags, while victim stands on a piece of paper. The paper is then folded and collected.
Bedding or the object upon which assault took place should be submitted to the lab.
Rape victim must be subjected to a medical examination Collected items include pubic hairs, vaginal swabs, blood, fingernail scrapings, clothing and urine (p 352)

37. Rape Suspect
Suspect must also undergo an exam. Routine items collected include clothing, hairs, penile swab and blood samples

38. Timeline
Living or motile sperm may survive 4 to six hours in the vagina of a living person.
Non-motile sperm may be found in a living female for up to three days and occasionally up to six days
Intact sperm (sperm with tails) are not normally found 16 hours but have been found as late as 72 hours after intercourse.

39. Important Considerations Based Upon Timeline
How long ago was the person raped?
When did voluntary sexual activity last occur prior to the sexual assault?
Blood is taken from any consensual partner having sex with the victim within 72 hours of the assault.

40. What are these?