1. Identification Using Bodily Fluids
Forensic Serology
Identification Using
Bodily Fluids
STEM

2. Forensic Serology
Serology – term used to describe a broad range of laboratory tests using reactions of blood serum and body fluid

5. Forensic Serology characterization of unknown blood
The serology section of a forensic laboratory deals with the following:
blood typing
characterization of unknown blood
stain patterns for crime reconstruction
paternity testing
DNA identification techniques

6. The Composition of Blood
Blood is a mixture of many components:
cells
inorganic substances (salts)
enzymes
water
proteins

7. The Composition of Blood
55 % of blood content is plasma – mostly water and substances dissolved in it
Most of the solid materials are cells
- red blood cells, RBCs (erythrocytes)
- white blood cells, WBCs (leukocytes)

8. Blood – Physical Characteristics
Adult ♂ contains 5-6L - Adult ♀ contains 4-5L
Temp is about 100.4 F
higher or lower than normal body T?
5 times as viscous as water
more or less resistant to flow than water?
what accounts for its viscosity?
pH ranges from 7.35 – 7.45 (slightly alkaline)
Color ranges from scarlet (oxygenated blood) to a deep red (deoxygenated blood).

9. Three questions that must be answered by the forensic investigator:
1) Is it blood?
Benzidine Test
Kastle-Meyer Test
Hemastix (o-tolidine, TMB)
Luminol Test
2) Is it human blood?
Precipitin Test
3) Can it be associated with an individual?

12. Luminol Luminol reacts with iron and becomes visible under UV light
Red blood cells contain hemoglobin (Hb) – for transporting oxygen, which is made of iron
Luminol reacts with iron and becomes visible under UV light
Luminol

13. Luminol

14. Blood Antigens
On the surface of red blood cells are chemical structures (proteins) called antigens
Antigens allow a living system to recognize foreign substances
Antigens also have characteristics and can be used to identify individuals
Human red blood cells have more than 15 different antigen types, but we’ll focus on two

15. Blood Typing
Blood typing involves determination of the antigens present on an individual’s RBCs

16. Blood Typing
The two most common blood typing systems are the A-B-O and the Rh methods
type A blood – contain “A” antigen on RBCs
type B blood – contain “B” antigen on RBCs
type AB blood – contains A & B antigens
type O blood – contain no A or B antigens
Rh+ blood – contains Rh antigen
Rh- blood – no Rh antigen

17. Blood Typing
When blood encounters free oxygen (like in a cut), the blood clots, or agglutinates
The clots can then be removed by the host system

18. Blood Typing
Human serum containing specific antibodies can be purchased
Separately mix a drop of unknown blood sample with drop of each anti-serum
Reaction between blood and anti-serum
No reaction between blood and anti-serum

19. Blood Stain Patterns

20. Dexter Blood Stain Pattern Video Clip

21. Catching Killers - Blood Stains 101 -Video Clip

22. Blood Stain Pattern Analysis
Categories of Bloodstains:
Passive (dripping)
Transfer (smearing)
Projected
Projected Bloodstains occur in shootings, trauma from blunt weapons, hacking, or slashing attacks.

23. Projected Bloodstain Analysis
Two Important Determinations:
a. direction of spatter
b. angle of impact with surface
sin  = (width drop / length drop)

24. Forensic Characterization of Saliva
Saliva is a mixture of many components:
99% water
Mucin (protein helps in swallowing)
Amylase (enzyme to digest carbos)
Cheek cells (good for DNA)
Adults produce liters of saliva/day and it is not uncommon at crime scenes (especially involving bite marks).

25. Forensic Characterization of Saliva
A simple test for saliva involves mixing starch, iodine, and a sample of the presumed saliva together.
Starch and iodine are a deep blue color when mixed together. The amylase breaks down starch, however, and the color fades
(takes about oC).