1. Blood Basics
Forensic Science
T. Trimpe

2. What makes up our blood?
RED BLOOD CELLS (Erythrocytes) – The most abundant cells in our blood; they are produced in the bone marrow and contain a protein called hemoglobin that carries oxygen to our cells.
WHITE BLOOD CELLS (Leukocytes) – They are part of the immune system and destroy infectious agents called pathogens.
PLASMA – This is the yellowish liquid portion of blood that contains electrolytes, nutrients and vitamins, hormones, clotting factors, and proteins such as antibodies to fight infection.
PLATELETS (Thrombocytes) – The clotting factors that are carried in the plasma; they clot together in a process called coagulation to seal a wound and prevent a loss of blood.

3. Blood Facts
The average adult has about FIVE liters of blood inside of their body, which makes up 7-8% of their body weight.
Blood is living tissue that carries oxygen and nutrients to all parts of the body, and carries carbon dioxide and other waste products back to the lungs, kidneys and liver for disposal. It also fights against infection and helps heal wounds, so we can stay healthy.
There are about one billion red blood cells in two to three drops of blood. For every 600 red blood cells, there are about 40 platelets and one white cell.

4. Genetics of Blood Types
Your blood type is established before you are BORN, by specific GENES inherited from your parents.
You inherit one gene from your MOTHER and one from your FATHER.
These genes determine your blood type by causing proteins called AGGLUTINOGENS to exist on the surface of all of your red blood cells.

5. AA or AO = Type A BB or BO = Type B OO = Type O AB = Type AB
What are blood types?
There are 3 alleles or genes for blood type: A, B, & O. Since we have 2 genes, there are 6 possible combinations.
Blood Types
AA or AO = Type A BB or BO = Type B OO = Type O AB = Type AB

6. Blood Typing
More than 15 blood antigen systems have been identified, but the A-B-O and Rh systems are the most important.
An individual that is type A has A antigens on his/her red blood cells, type B has B antigens, type AB has both A and B antigens, and type O has neither A nor B antigens.
Rh factor is determined by the presence of another antigen, the D antigen.
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7. Blood Typing
People having the D antigen are Rh positive; those not having the D antigen are Rh negative.
For every antigen, there is a specific antibody that will react with it to form clumps known as agglutination.
Thus if serum containing anti-B is added to red blood cells carrying B antigen, they will immediately react.
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8. Rh Factors A+ A- B+ B- AB+ AB- O+ O-
Scientists sometimes study Rhesus monkeys to learn more about the human anatomy because there are certain similarities between the two species. While studying Rhesus monkeys, a certain blood protein was discovered. This protein is also present in the blood of some people. Other people, however, do not have the protein.
The presence of the protein, or lack of it, is referred to as the Rh (for Rhesus) factor.
If your blood does contain the protein, your blood is said to be Rh positive (Rh+). If your blood does not contain the protein, your blood is said to be Rh negative (Rh-).
A+ A- B+ B- AB+ AB- O+ O-

9. How common is your blood type?
46.1%
38.8%
11.1%
3.9%

10. Blood Transfusions O A B AB
A blood transfusion is a procedure in which blood is given to a patient through an intravenous (IV) line in one of the blood vessels. Blood transfusions are done to replace blood lost during surgery or a serious injury. A transfusion also may be done if a person’s body can't make blood properly because of an illness.
Who can give you blood?
People with TYPE O blood are called Universal Donors, because they can give blood to any blood type.
People with TYPE AB blood are called Universal Recipients, because they can receive any blood type.
Rh +  Can receive + or -
Rh -  Can only receive - A B O AB
Universal Donor
Universal Recipient

11. Blood Evidence
Blood samples – Can be analyzed to determine blood type and DNA, which can be matched to possible suspects.
Blood droplets – Can be analyzed to give clues to the location of a crime, movement of a victim, and type of weapon.
Blood spatter – Can be analyzed to determine patterns that give investigators clues to how a crime might have happened.

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

13. Forensics of Blood
The criminalist must be prepared to answer the following questions when examining dried blood:
Is it blood?
From what species did the blood originate?
If the blood is of human origin, how closely can it be associated with a particular individual?
The determination of blood is best made by means of a preliminary color test.
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14. Luminol with false positive (bleach)
Testing for Blood
A positive result from the Kastle- Meyer color test is highly indicative of blood. Hemoglobin causes a deep pink color.
Alternatively, the luminol test is used to search out trace amounts of blood located at crime scenes.
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Luminol with false positive (bleach)

15. Luminol with false positive (bleach)
Testing for Blood
Luminol produces light (luminescence) in a darkened area.
Luminol with false positive (bleach)
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16. Testing for Blood
Microcrystalline tests, such as the Takayama and Teichmann tests, depend on the addition of specific chemicals to the blood so that characteristic crystals will be formed.
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17. Testing for Blood
Once the stain has been characterized as blood, the precipitin test will determine whether the stain is of human or animal origin.
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18. Testing for Blood
The precipitin test uses antisera normally derived from rabbits that have been injected with the blood of a known animal to determine the species origin of a questioned bloodstain.
Once it has been determined that the bloodstain is of human origin, an effort must be made to associate or dissociate the stain with a particular individual.
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19. Testing for Blood
DNA analysis has allowed forensic scientists to associate blood with a single individual.
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20. A-B-O vs. DNA
Prior to the advent of DNA typing, bloodstains were linked to a source by A-B-O typing and the characterization of polymorphic blood enzymes and proteins.
This approach has now been supplanted by the newer DNA technology.
DNA analysis has allowed forensic scientists to associate blood and semen stains with a single individual.
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21. Heredity and Paternity
The transmission of hereditary material is accomplished by means of microscopic units called genes, located on chromosomes.
Alternative forms of genes that influence a given characteristic (such as eye color or blood type) are known as alleles.
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22. Heredity and Paternity
Paternity testing has historically involved the A-B-O blood typing system along with blood factors other than A-B-O.
Currently, paternity testing has implemented DNA test procedures that can raise the odds of establishing paternity beyond 99 percent.
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23. Testing for Seminal Stains
Many of the cases sent to a forensic laboratory involve sexual offenses, making it necessary to examine exhibits for the presence of seminal stains.
The best way to locate and characterize a seminal stain at the same time is to perform the acid phosphatase (an enzyme secreted into seminal fluid) color test.
A purple color indicates the acid phosphatase enzyme.
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24. Testing for Seminal Stains
Semen can be identified either by the presence of spermatozoa or of p30, a protein unique to seminal plasma.
Forensic scientists can successfully link seminal material to an individual by DNA typing.
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25. Rape Evidence
The rape victim must undergo a medical examination as soon as possible after the assault.
At that time, the appropriate items of physical evidence, including clothing, hairs, and vaginal and rectal swabs, can be collected for subsequent laboratory examination.
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26. Rape Evidence
All outer and undergarments should be carefully removed and packaged separately in paper (not plastic) bags.
Bedding, or the object upon which the assault took place, may also be carefully collected.
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27. Rape Evidence
If a suspect is apprehended within 24 hours of the assault, it may be possible to detect the victim’s DNA on the male’s underwear or on a penile swab of the suspect.
Items routinely collected from the suspect include all clothing, pubic hair, head hair, penile swab, and a blood sample or buccal swab for DNA typing.
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28. Rape Evidence
The forceful physical contact between victim and assailant may result in a transfer of such physical evidence as blood, semen, saliva, hairs, and fibers.
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