1. Body Fluids
Forensic Serology

2. How is blood evidence detected at a crime scene?
Light Source
Investigators will first examine the crime scene to look for areas that may contain blood. They may use a high-intensity light or UV lights to help them find traces of blood as well as other bodily fluids that are not visible under normal lighting conditions.
Blood Reagent Tests
These tests, referred to as presumptive tests, are used to detect blood at crime scenes based upon the properties of hemoglobin in the blood. Further tests at the crime lab can determine if it is human blood or not.
Examples:
Phenolphthalein is a chemical that is still utilized today and is usually referred to as the Kastle-Meyer test and produces a pink color when it reacts with hemoglobin.
HemaStix is a strip that has been coated with tetramethylbenzidine (TMB) and will produce a green or blue-green color with the presence of hemoglobin.
HemaStix

3. Fluorescein Reaction in UV Light
Luminol
This chemical is used by crime scene investigators to locate traces of blood, even if it has been cleaned or removed.
Investigators spray a luminol solution is throughout the area under investigation and look for reactions with the iron present in blood, which causes a blue luminescence.
One problem is that other substances also react, such as some metals, paints, cleaning products, and plant materials. Another problem is that the chemical reaction can destroy other evidence in the crime scene.
Luminol Reaction
Fluorescein
This chemical is also capable of detecting latent or old blood, similar to luminol. It is ideal for fine stains or smears found throughout a crime scene. After the solution has been sprayed onto the substance or area suspected to contain blood, a UV light and goggles are used to detect any illuminated areas, which appear greenish-white if blood is present. It may also react to many of the same things as luminol (copper and bleach).
Fluorescein Reaction in UV Light
LCV or Leuco Crystal Violet, is one type of chemical process that is used for blood enhancement. Using this test helps to make the blood evidence more visible so it can be photographed and analyzed.

4. Bloodstain Pattern Analysis Terms
Spatter – Bloodstains created from the application of force to the area where the blood originated.
Origin/Source – The place from where the blood spatter came from or originated.
Angle of Impact – The angle at which a blood droplet strikes a surface.
Parent Drop – The droplet from which a satellite spatter originates.
Satellite Spatters – Small drops of blood that break of from the parent spatter when the blood droplet hits a surface.
Spines – The pointed edges of a stain that radiate out from the spatter; can help determine the direction from which the blood traveled.
Parent Drop
Spines
Satellite Spatters

5. Types of Bloodstain Patterns
Passive Bloodstains
Patterns created from the force of gravity
Drop, series of drops, flow patterns, blood pools, etc.
Projected Bloodstains
Patterns that occur when a force is applied to the source of the blood
Includes low, medium, or high impact spatters, cast-off, arterial spurting, expiratory blood blown out of the nose, mouth, or wound.
Transfer or Contact Bloodstains
These patterns are created when a wet, bloody object comes in contact with a target surface; may be used to identify an object or body part.
A wipe pattern is created from an object moving through a bloodstain, while a swipe pattern is created from an object leaving a bloodstain.
Images from

6. Microscopic Views Bird Blood Fish Blood Horse Blood Cat Blood
Dog Blood
Fish Blood
Frog Blood
Snake Blood
Microscopic Views
Human Blood
Horse Blood

7. The Precipitin Test
When human blood is introduced to the animal’s anti- human antibodies it produces a clot called a precipitate clot. This precipitate clot can be formed in a test valve identifying whether or not a blood sample is human or not. This test is called the Precipitin Test. 
1.      Animal is injected with human blood
2.      Animal makes anti-human antibodies
3.      Animal blood is extracted
4.      The extracted animal blood is used to test other blood to identify whether the blood is of human origin

9. Bloodstain Evidence May reveal:
Origin(s) of bloodstain
Distance of bloodstain from target
Direction from which blood impacted
Speed with which blood left its source
Position of victim & assailant
Movement of victim & assailant
Number of blows/shots

10. Liquid Blood Physical properties Behaves as a projectile in motion
Viscosity
Surface tension
Specific gravity (relative density)
Behaves as a projectile in motion
Biology, physics, mathematics…

11. Surface Tension Smallest SA to Volume ratio is offered by sphere
Resistance to penetration & separation
Surface acts to reduce surface area
Smallest SA to Volume ratio is offered by sphere

12. Blood Drips 1. Blood trickles downwards
2. Blood drop grows until Wt (G) > S.T.
Single drop breaks free (teardrop shape)
3. Surface tension pulls in vertically
4. And horizontally
5. Shape settles into sphere (0.05 ml)
Does not break up until impact

13. . . . Drop size Standard drop size 50ul (0.05ml) Rapid bleeding gives
slightly larger drop
Shaking/movement
casts off smaller drops . . .

14. Free Falling Blood Droplets
0.06 ul
1.1 mm
0.5 to
0.65 m .
2.2 m/s
0.12 ul
1.32 mm
0.84
to 1 m .
3.3 m/s
0.5 ul
2.12 mm
2.4 to
3 m .
4.6 m/s .
50 ul
4.6 mm
7.5 m/s
4.2 to
5.4 m

15. Shape & Size of Bloodspot
The size of a blood spot depends on distance fallen and surface type.

16. Shape & Size of Bloodspot
Depends mostly on nature of target surface
texture (rough or smooth)
porous or non porous
Size is related to distance fallen, provided:
standard 50 ul drop of blood
There is little change in spot diameter beyond a fall distance of 1.2 m

17. Effect of Target Surface. .
Smooth Surface Rough Surface .
Spreads out smoothly
ST of spreading edge is
broken by irregular surface

18. Single drop of blood falling from various heights (m) onto various surfaces
0.5 1 2 3
0.5 1 2 3
Height/Surface
smooth
floor
paper
towel
fabric

19. Height Fallen
Single drops of blood falling from fingertip onto smooth cardboard from various heights.
No change in diameter beyond 7 ft.
Adapted from
Introduction to Forensic Sciences,
W. Eckert, CRC, 1997

20. Experiments with Falling Blood Droplets
dropper
ruler
Height
Target Surface
Fabric (theatre green)
rough paper towel
paper
whiteboard
Terazzo floor

21. Angle of Impact Gravitational dense zone at lower edge 90 80 70 60
50
40
Gravitational dense zone
at lower edge
20
30
10
Adapted from
Introduction to Forensic Sciences,
W. Eckert, CRC, 1997

22. At 90°, blood stains will be almost circular
At 90°, blood stains will be almost circular. Below 75°, spines become more prominent on the side of the spatter opposite the angle of impact. At very low angles, a second, satellite spatter may break off, forming a distinctive “exclamation point” stain pattern.

23. . Wave Cast-off Tail of elongated stain points in direction of travel
Tail of wave cast-off points
back to parent drop
Parent drop
wave cast-off