1. Chapter 8 Blood and Blood Splatter By the end of this chapter you will be able to:
Explain the composition of blood
Describe the function of blood cells
Determine the blood type of a blood sample
Conduct a blood splatter analysis
Examine wounds and describe the nature of the weapon
Find and process blood evidence

2. Introduction and History
Blood typing provides class evidence
DNA profiling provides individual evidence
A blood splatter pattern provides information
the truthfulness of an account by a witness or a suspect
the origin of the blood
the angle and velocity of impact
the type of weapon used

3. Blood History – studied for thousands of years!
Date
Who
Contribution
1628
Sir William Harvey
Noted continuous circulation within the body
1874
Sir William Osler
Discovered platelets
1901
Karl Landsteiner
Discovered types: A, B, O
1940
Discovered Rh protein
1959
Dr. Max Perutz
Described structure of hemoglobin
1971
Dr. Blumberg
Developed method of antibody detection
Various
Blood screening tests for infectious diseases

4. Composition of Blood Blood is a circulating tissue consisting of:
Red blood cells (Erthrocytes)—carries oxygen to the body’s cells and carbon dioxide away
White blood cells (Leukocytes)—fights disease and foreign invaders and, alone, contain cell nuclei
Platelets (Thrombocytes)-aids in blood clotting and the repair of damaged blood vessels
Plasma—a liquid suspending other blood components

5. Composition of Blood

6. Cellular Components of Blood
The immune system functions to protect our bodies by identifying cells or molecules that are foreign, such as viruses, bacteria, and other parasites.
White blood cells secrete proteins, antibodies that assist in the immune response.

7. Blood Typing—Proteins
1982 white blood cells were used as a source of DNA by Dr. Alec Jeffreys to produce the first DNA profile
Discovered in 1900 by Karl Landsteiner – blood cannot be freely mixed with anothers blood
Identifies the presence or absence of particular proteins embedded in the cell
Quicker and less expensive than DNA profiling
Produces class evidence but can still link a suspect to a crime scene or exclude a suspect

8. Blood Enzymes
Enzymes are complex proteins that catalyze different biochemical reactions
Many enzymes and proteins have been found in the blood that are important for identification purposes
The more enzymes available for testing, the easier it will be to identify a person.
Examples: Phosphoglucomutase (PGM)
Adenylate kinase (AK)
Adenosine deaminase (ADA)
Esterase D (EsD)
Glucose-6-phosphate dehydrogenase (G-6-PD)
Haptoglobins (Hp)

9. Blood Typing—Antibodies
Agglutination – clumping occurs when one arm of the Y shaped antibody attaches to the red blood cell, the second arm attaches to another red blood cell.
Blood Typing—Antibodies
Antibodies are Y-shaped proteins secreted by white blood cells that attach to antigens to destroy them
Antigens are foreign molecules or cells that react to antibodies
Ex. Viruses, bacteria, red blood cells from another person
**There are more than 300 know blood group proteins and more than 1
million different protein binding sites on each red blood cell.

10. Blood Typing—Proteins
42% 12% 3% 43%
of the population in the United States
If a person contains only protein A = A blood
If a person contains only protein B = B blood type
If the person’s blood has both the A and the B proteins, then he or she
has type AB blood.

11. Rh Factor
85% of the population has a protein called RH factor on their blood cells
People with Rh+ can get Rh+ and Rh-
Rh- can only get Rh-

12. Blood Typing
Blood Typing

13. Blood typing!

14. Blood Typing
The Blood Typing Game

15. Blood Typing Antibodies fight antibodies Donor Receiver 0 0 A A B B
A A
B B
AB AB
Blood group A A antigens on the surface of your red blood cells and B antibodies in your blood plasma.
Blood group B B antigens on the surface of your red blood cells and A antibodies in your blood plasma.
Blood group AB A and B antigens on the surface of your red blood cells and no A or B antibodies at all in your blood plasma.
Blood group 0
neither A or B antigens on the surface of your red blood cells, have both A and B antibodies in your blood plasma.

16. Blood Typing —Probability and Blood Types
The probability of a blood type equals the product of probabilities for each protein group
If Type A = 42% and Rh Factor = 85%
Then A+ = .42 x .85 = .357 (35.7%)
Knowing additional proteins and enzymes in the blood sample
Narrows the population group
Increases the probability of identifying a suspect
A %
B %
AB 3%
O %
MM 30%
MN 48%
NN %
Rh %
Rh %
Hp %
PGM-2 6%

17. Probabilities What percentage of the population has A+
.42 X .85 = % Therefore about 36 out of every 100 people
What percentage has O- ,MN
.43 X .15 X .48 = % of the population!
What percentage has A,NN,Hp-1,Rh-,PGM-2
.42 X .22 X .14 X .15 X .06 = % of the population
Again, by testing for more blood-type proteins, the probability for uniqueness continues to increase, and the number of other people with the same combination as our suspect decreases.

18. Blood Spatter

19. Blood Splatter 1939—splatter patterns first analyzed
Today, blood spatter evidence is used to explain events at a violent scene
Blood may splatter when a wound is inflicted
Blood splatter pattern—a grouping of blood stains
Patterns help to reconstruct the events surrounding a shooting, stabbing, or beating

20. Blood Splatter Analysis
Analysis of a splatter pattern can aid in determining the:
direction blood traveled
angle of impact
point of origin of the blood
velocity of the blood
manner of death

21. Blood Splatter Analysis
Natural cohesiveness of blood

22. Blood Splatter Analysis
Satellite droplets—
When blood falls from a height, or at a high velocity,
It overcomes its natural cohesiveness, and
separates from the main droplet
Spiking patterns—
Form around the droplet edges when blood falls onto a less-than-smooth surface

23. Blood Splatter Analysis —Six Patterns
Describe each of these:
Passive drops - dropped at 90 degrees
Arterial gushes - walls or ceilings cause by pumping
Splashes - exclamation point
Smears – bleeding victim leaving blood as they brush against something Ex. wall
Trails - bleeding victim moving locations
Pools – bleeding heavily and remaining in one place

24. Blood Descriptions Round – dropped at 900
Tails or satellites – determine directionbb
Spatter – type of pattern
>3mm Low velocity
1-3mm Medium Velocity
<1mm High Velocity
fine mist – high velocity impact EX. Gunshot
Cast off –lower velocity EX. Hit with bat
Voids – person was moved

25. Blood Splatter Analysis —Impact
Patterns can help investigators determine the type of weapon used
What kind of a pattern is produced by a gun shot?
What kind of a pattern is produced by a hammer blow?

26. Blood Splatter Analysis —Directionality
Adhesion – force between two unlike surfaces
Surface tension -elastic characteristic along the outer edge of a liquid caused by the attraction of like molecules
The shape of an individual drop of blood provides clues to the direction from where the blood originated.
How will the point of impact compare with the rest of a blood pattern?

27. Blood Splatter Analysis
Lines of convergence—two or more blood splatters can pinpoint the location of the blood source

28. Crime Scene Investigation of Blood
Search for blood evidence
Determine
Is the evidence blood?
Is the blood human?
What is the blood type?
Interpret the findings:
Does the blood type match a suspect’s blood?
If not, exclude that suspect
If yes, decide if DNA profiling is necessary

29. Summary
Blood consists of cellular components and plasma.
The various human blood types are caused by the presence or absence of A and/or B proteins on the surface of red blood cells.
Blood splatter evidence can be used to recreate a crime scene.
Investigators endeavor to (a) locate, (b) identify, and (c) interpret blood splatter patterns at crime scenes.