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Serology
Body fluids and the stains they leave
at crime scenes
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Common Types of Serology
 Commonly found rape cases are:
 Blood
 Hair
 Sperm
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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.
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True or False
 No two individuals, except for
identical twins, could be expected to
have the same combination of blood
factors.
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Prior to 1990, A-B-O system
provided the best means for
forensic scientists to link blood
to an individual.
What changed in 1990?
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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
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Blood Stains on Victim’s Jeans
Sections removed &
initialed for testing
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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?
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Species Identification
 Prior to 1990,
double immunodiffusion plate was
used for species
identification of
blood stains.
 Today scientists
simply test using
DNA techniques
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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 greenishblue.
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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.
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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
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http://www.flickr.com/photos/jackofspades/4376209354/
Figure 12-5 p. 337 Saferstein Criminalistics, 2004
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A Bloody Knife from a Homicide
Scene.
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From what species did it originate?
 Preciptin Test
>Very sensitive
>Requires only a small sample
>Even dried bloodstains from 10-15
years ago can be tested.
>Positive test results even in diluted
samples
 Gel diffusion
See pp. 338-339 Saferstein, Criminalistics, 2004.
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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.
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Rape Statistics
 http://www.rainn.org/statistics
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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.

http://www.houstonpi.com/sementrace/videos.html
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Microscopic Examination
 Semen can be identified by the
presence of spermatazoa @ 400x
magnification
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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)
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p30 or Prostate Specific Antigen
 Protein discovered in 1970’s
 Unique to seminal plasma
 See Criminalistics pp. 351 & 352
Figure 12-6 and Figure 12-17 for PSA
testing by precipitation and
electrophoresis
 If semen is present, DNA testing is
used to link seminal material to an
individual. More later. . . .
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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
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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.
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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
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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
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DNA Testing
 Extremely sensitive- characterization
possible with only 1 billionth of a
gram of sample
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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.
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