1. Forensic Serology Chapter 11
Forensic Science
Amy Urling

2. Forensic Serology
Serology: study of bodily fluids

3. Blood
Plasma: liquid portion of blood; 55% of volume; includes dissolved proteins, carbohydrates, fats, salts, minerals, antibodies
Red blood cells (erythrocytes): formed in bone marrow, responsible for transport of oxygen and carbon dioxide, have no nucleus
White blood cells (leukocytes): formed in lymph nodes, protect our bodies against invading pathogens
Platelets: part of blood clotting process

4. Label red blood cells, white blood cells, plasma
Where is the DNA?

5. Is this human blood?

6. Locating Blood
Luminol: undergoes chemiluminescence; causes blood or blood residue to appear blue to yellow-green in the dark
Fluorescein: emits light in contact with blood, can be sprayed on vertical surfaces
Phenolphthalien: turns pink in the presence of a base (or blood)
Teichmann and Takayama Tests: confirm the presence of blood by turning it into crystals

7. ABO Blood Types A B AB O Blood Type Antigens Antibodies % of Pop.
Can Receive
Can Donate To A B AB O

8. Rh Factor + has Rh antigen
- doesn’t have Rh antigen and has Rh antibodies

9. Questions Answered by Blood Spatter Interpretation
Chapter 10
Questions Answered by Blood Spatter Interpretation
The distance between the target surface and the origin of the blood
The point(s) of origin of the blood
Movement and direction of a person or an object
The number of blows, shots, etc., causing the bloodshed and/or the dispersal of blood
Type and direction of impact that produced the bloodshed
The position of the victim and/or object during bloodshed
Movement of the victim and/or object after bloodshed
Kendall/HUnt

10. Blood Spatter: Conditions Affecting Shape of Blood Droplet
Chapter 10
Blood Spatter: Conditions Affecting Shape of Blood Droplet
Size of the droplet
Angle of impact
Velocity at which the blood droplet left its origin
Height
Texture of the target surface
On clean glass or plastic—droplet will have smooth outside edges
On a rough surface—will produce scalloping on the edges
Kendall/HUnt

11. Bloodstain Terminology
Chapter 10
Bloodstain Terminology
Angle of impact—angle at which blood strikes a target surface
Bloodstain transfer—when a bloody object comes into contact with a surface and leaves a patterned blood image on the surface
Backspatter—blood that is directed back toward the source of
energy
Cast-off—blood that is thrown from an object in motion
Kendall/HUnt

12. Bloodstain Terminology, continued
Chapter 10
Bloodstain Terminology, continued
Contact stain—bloodstains caused by contact between a wet blood- bearing surface and a second surface that may or may not have blood on it
Transfer—an image is recognizable and may be identifiable
with a particular object
Swipe—wet blood is transferred to a surface that did not
have blood on it
Wipe—a non-blood-bearing object moves through a wet
bloodstain, altering the appearance of the original stain
Kendall/HUnt

13. Bloodstain Terminology, continued
Chapter 10
Bloodstain Terminology, continued
Directionality—relates to the direction a drop of blood travels in space from its point of origin
Terminal velocity—the greatest speed to which a free-falling drop of blood can accelerate in air. It is dependent upon the acceleration of gravity and the friction of the air against the blood—approximately 25.1 feet/second.
High velocity—greater than 25 feet per second, usually feet per second; gives a fine mist appearance
Medium velocity—5 to 25 feet per second
Low velocity—5 feet per second or less
Kendall/HUnt

14. Impact The shape of a blood drop:
Chapter 10
Impact
The shape of a blood drop:
Round—if it falls straight down at a 90-degree angle
Elliptical—blood droplets elongate as the angle decreases from 90 to 0 degrees; the angle can be determined by the following formula:
The more acute the angle of impact, the more elongated the stain (and easier it is to determine direction of travel)
90-degree angles are perfectly round drops; 80-degree angles take on a more elliptical shape.
At about 30 degrees the stain will begin to produce a tail.
Kendall/HUnt

15. Chapter 10
Bloodstain Patterns
The harder and less porous the surface, the less the blood drop will break apart.
The softer and more porous the surface, the more the blood drop will break apart.
The pointed end of the bloodstain faces the direction of travel.
Kendall/HUnt

16. Area of Intersection and Convergence
Chapter 10
Area of Intersection and Convergence
The location of the blood source can be determined by drawing lines from the various blood droplets to the point where they intersect.
The area of convergence is the point of origin—the spot where the “blow” occurred. It may be established at the scene by measurement of angles with the use of strings.
Kendall/HUnt