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

7. 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

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. 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.

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

11. Forensic Science Lab Activity
Bloodstain Science
Forensic Science Lab Activity
Warning: Some material in this presentation and related videos may be too graphic for some people.
T. Trimpe

12. How does a blood droplet form? Click the image for an animation.
What does the abbreviation BPA represent? Bloodstain Pattern Analysis
What can an investigator learn from the analysis of a blood spatter?
 Type and velocity of weapon
 Number of blows
 Handedness of assailant (right or left-handed)
 Position and movements of the victim and assailant during and after the attack
 Which wounds were inflicted first
 Type of injuries
 How long ago the crime was committed
 Whether death was immediate or delayed
Source:
How does a blood droplet form? Click the image for an animation.

13. 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.
Kastle-Meyer Test
Video
HemaStix

14. 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.

15. 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

16. Types of Bloodstain Patterns
Blood Spatter Movie
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.
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