1. Body fluids and the stains they leave at crime scenes
Serology
Body fluids and the stains they leave at crime scenes
2009©Forensic Science Today

2. Common Types of Serology
Commonly found rape cases are:
Blood
Hair
Sperm
2009©Forensic Science Today

3. History of Blood Typing
1901- Karl Landsteiner, recognized differences in human blood
Received Nobel Prize in 1929
Critical in blood transfusions
A-B-O classification system
Rh factor in blood was demonstrated in 1937
More than 100 different blood factors are known today.
2009©Forensic Science Today

4. 2009©Forensic Science Today
True or False
No two individuals, except for identical twins, could be expected to have the same combination of blood factors.
2009©Forensic Science Today

5. 2009©Forensic Science Today
Prior to 1990, A-B-O system provided the best means for forensic scientists to link blood to an individual.
What changed in 1990?
2009©Forensic Science Today

6. 2009©Forensic Science Today
Components of Blood
Cellular-Solid materials suspended in plasma that makes up 45% of “blood”
Red Blood Cells (RBC)-erythrocytes
White Blood Cells (WBC)-leukocytes
Platelets
Plasma – 55%- fluid portion of unclotted blood-mostly water
Antibodies
Enzymes
Proteins
Serum= liquid that separates from the blood when a
clot is formed
2009©Forensic Science Today

7. Blood Stains on Victim’s Jeans
Sections removed & initialed for testing
2009©Forensic Science Today

8. Forensic Characterization of Bloodstains
Is it blood?
From what species did it originate?
If the blood is of human origin, how closely can it be associated to a particular individual?
2009©Forensic Science Today

9. Species Identification
Prior to 1990, double immuno-diffusion plate was used for species identification of blood stains.
Today scientists simply test using DNA techniques
2009©Forensic Science Today

10. Techniques to Visualize
Kastle-Meyer – uses H2O2 + phenolphthalein to produce a bright pink color in the detection of peroxidase activity in blood
Leucomalachite green. Leucomalacite green is dropped on the suspect stain. A positive blood result will immediately turn the swab greenish-blue.
2009©Forensic Science Today

11. 2009©Forensic Science Today
More Visualization
Tetramethylbenzidine- test by placing drops on a suspect stain. A positive reaction is indicated by an intense blue color.  
Luminol- Luminol is also a field test that you may have seen on one of the forensic investigation television shows. It involves spraying the chemical onto the suspected bloodstain and viewing it in total darkness. If blood is present, it will begin to luminesce (glow a whitish-blue) within 5 seconds.
2009©Forensic Science Today

12. 2009©Forensic Science Today
Luminol Test
Extremely Sensitive- capable of detecting bloodstains diluted up to 300,000 times
Large areas are sprayed and viewed in darkened areas for emission of light
Does not interfere with subsequent DNA testing
Figure 12-5 p. 337 Saferstein Criminalistics, 2004
2009©Forensic Science Today

13. A Bloody Knife from a Homicide Scene.
Here a forensic serologist will sample areas she believes may contain blood and test them for the presence of blood using the Kastle-meyer, or other visualization techniques. If the results of the test are positive the stain will be collected with a swab and placed in storage (refrigerated at -80F) for DNA testing.
2009©Forensic Science Today

14. From what species did it originate?
Preciptin Test
>Very sensitive
>Requires only a small sample
>Even dried bloodstains from years ago can be tested.
>Positive test results even in diluted
samples
Gel diffusion
See pp Saferstein, Criminalistics, 2004.
2009©Forensic Science Today

15. Applications of Genotyping Blood Factors
No direct relevance to Criminal Investigations
Paternity Testing
Blood type may clear
a suspect
Example: Child is type AB
Mother is type AB
Suspected Father is type O
Draw the Punnett Square.
2009©Forensic Science Today

16. 2009©Forensic Science Today
Rape Statistics
2009©Forensic Science Today

17. Forensic Characterization of Semen
Locate the stain and screen for semen with the acid phosphatase color test
Acid phosphatase is an enzyme present in high concentrations in semen
Suspect stain is transferred to filter paper; reagent is added. If semen is present, sample will fluoresce under UV light within 30 seconds.
2009©Forensic Science Today

18. Microscopic Examination
Semen can be identified by the presence of 400x magnification
2009©Forensic Science Today

19. Challenges for the Microscopist
Sample collection: Sperm bind tightly to cloth materials, are extremely brittle when dry, and disintegrate if the stain is washed or rubbed against another object
Oligospermia – abnormally low sperm count
(prefix Oligo means “just a few or scant”
Aspermia- absence of sperm or sterility (partly due to growing popularity of vasectomies)
2009©Forensic Science Today

20. p30 or Prostate Specific Antigen
Protein discovered in 1970’s
Unique to seminal plasma
See Criminalistics pp. 351 & 352 Figure 12-6 and Figure for PSA testing by precipitation and electrophoresis
If semen is present, DNA testing is used to link seminal material to an individual. More later
2009©Forensic Science Today

21. Collection of Rape Evidence
Forceful physical contact between victim and assailant may result in the transfer of hair, fibers, blood, and semen (Locard’s Exchange Principle)
Carefully package all outer garments and undergarments separately in PAPER bags.
Victim should stand on paper while undressing so that any loose fibers can be collected for analysis.
Collect bedding, if appropriate
2009©Forensic Science Today

22. Collection of Rape Evidence
Disposable latex gloves are essential for handling evidence!
DNA may be transferred
through perspiration.
Investigators must avoid direct personal contact with evidence.
2009©Forensic Science Today

23. Victim needs a medical exam ASAP! Evidence collection kit includes
Pubic combings & standard/reference samples
External genital skin areas
Vaginal swabs & smear
Cervix swabs
Rectal swabs & smear
Oral swabs & smear
Head hairs
Blood sample
Fingernail scrapings
All clothing
Urine specimen (for drug testing e.g. Rohypnol, GHB)
Swab of any area that may have assailant’s saliva for DNA testing
See Saferstein, Criminalistics, 2004, p. 353
2009©Forensic Science Today

24. Evidence from Suspect, if apprehended
All clothing
Pubic Hair combings
Pulled head and pubic hair standard/reference samples
Penile swab taken within 24 hours after assault
Blood sample or buccal swab for DNA testing
2009©Forensic Science Today

25. 2009©Forensic Science Today
DNA Testing
Extremely sensitive- characterization possible with only 1 billionth of a gram of sample
2009©Forensic Science Today

26. 2009©Forensic Science Today
Timing
Sperm can survive up to 4-6 hours in the vaginal cavity of a living female.
Time of sexual attack may be determined.
Nonmotile sperm may be found up to 3 days after intercourse.
Acid phosphatase can be detected in the vaginal cavity for up to 48 hours after intercourse. p30 can be detected for 24 hours.
2009©Forensic Science Today

27. 2009©Forensic Science Today