1. Blood “Out damned spot! Out, I say
Here’s the smell of the blood still,
All the perfumes of Arabia will not
Sweeten this little hand. Oh, Oh, Oh!”
—William Shakespeare’s Lady Macbeth, in Macbeth

2. Unknown Stains at a Scene
Questions to be answered:
Is it blood?
Is it human blood?
Whose is it?
Determine blood type.
What caused the blood spatter?
Determine the method(s) in which blood may have been deposited.

3. Introduction
Blood typing can provide class evidence; whereas DNA profiling can provide individual evidence.

4. Blood Characteristics
Whole blood carries cells and plasma—the fluid with hormones, clotting factors, and nutrients.
Shown below:
Red (Erythrocyte) blood cells carry oxygen to the body’s cells and carbon dioxide away.
Platelets aid in blood clotting and the repair of damaged blood vessels.
White (Leukocyte) blood cells fight disease and foreign invaders and, alone, contain cell nuclei.
Erythrocyte Platelet Leukocyte

5. Blood Typing What are the four types of blood? A, B, AB, and O
What do we use to identify the blood types?
ABO Blood Typing
What is the population distribution in the US?
Type
Percent O A B AB 45 40 11 4

6. Blood Typing What is the difference between the types?
Antigen – cells are located on the red blood cell.
Antibody—are proteins secreted by white blood cells that attach to antigens to destroy them, located outside the red blood cell.
Agglutination—clumping of red blood cells; will result if blood types with different antigens are mixed

7. Blood Group A
Has A antigens on the surface of red blood cells and B antibodies in blood serum.
The B antibodies will attack and destroy Type B blood cells when they are introduced into the body.
Can give blood to A and AB, can received blood from O and A

8. Blood Group B
Has B antigens on the surface of red blood cells and A antibodies in blood serum.
The A antibodies will attack and destroy Type A blood cells when they are introduced into the body.
Can give blood to B and AB; can receive blood from O and B

9. Blood Group AB
Has both A + B antigens on the surface of red blood cells + NO A or B antibodies in blood serum.
Will not reject or attack any blood types = Universal Recipient
Can give blood to AB, can receive blood from A, B, O, and AB

10. Blood Group O
Has NO A or B antigens on the surface of red blood cells but has BOTH A + B antibodies in blood serum.
Will not “provoke” and attack by any antibodies = Universal Donor
Can give blood to A, B, O, and AB; can receive blood from O

11. Blood Groups Type Antigen Antibody A A B A, AB O, A B, AB O , B B B A
Can Give
Blood To
Can Get
Blood From
Type
Antigen
Antibody A A B
A, AB
O, A
B, AB
O , B B B A
Neither
A nor B AB
A and B AB
A, B, O, AB
Universal Acceptor
Neither
A nor B O
A and B
A, B, O, AB O
Universal Donor

12. * This is why we have positive (O+) and negative (B-) blood types!
Rh Factor
A certain blood protein was discovered while studying Rhesus Monkeys called: Rh
If this protein is present in your blood, you
are: Rh+ (positive).
If your blood lacks this protein, you are:
Rh- (negative).
* This is why we have positive (O+) and negative (B-) blood types!

13. Presumptive Tests for Blood Determination
Kastle-Meyer color test—a mixture of phenolphthalein and hydrogen peroxide; the hemoglobin will cause the formation of a deep pink color if blood is present
Hematest® tablet—reacts with the heme group in blood causing a blue-green color
Luminol test—reaction with blood to produce light

14. Human vs Animal Blood Microscopic observation
RBC in animal has a nucleus
RBC in human no nucleus
Frog Blood
Human Blood

15. Human vs Animal Blood Precipitin test
Blood is injected into a rabbit; antibodies are formed; the rabbit’s blood is extracted as an antiserum; the antiserum is placed on sample blood. The sample will react with human proteins if human blood is present. This test is very sensitive and requires only a small amount of blood.