1. FORENSIC SCIENCE

3. WHAT IS FORENSIC SCIENCE?

4. WHAT IS FORENSIC SCIENCE?
Forensic scientists collect, preserve, and analyse scientific evidence during the course of an investigation. While some forensic scientists travel to the scene to collect the evidence themselves, others occupy a purely laboratory role, performing analysis on objects

5. FORENSIC SCIENTISTS INVESTIGATE THE DETAILS OF A CRIME SCENE

7. BLOOD SPATTER A FEW FACTS ABOUT BLOOD…
What are the components of blood?
Why is blood so important?
What can blood tell us about a crime scene?

8. WHAT ARE THE COMPONENTS OF BLOOD?
FYI: An average body contains 0.2 mg of gold, which is in our blood

9. 1. RED BLOOD CELLS RBC AKA: Erythrocytes 45% of the volume
Hemoglobin: protein that carries oxygen to all tissues of the body and carbon dioxide away from tissue and back to the lungs (RESPIRATION)
It takes about 30 seconds for a RBC to make a complete trip around your body

10. 2. WHITE BLOOD CELLS WBC AKA: Leukocytes 1 WBC to every 700 RBC
Defend against infections by surrounding and engulfing (eating) the bacteria

11. 3. PLATELETS AKA: Thrombocytes 1 platelet to every 20 RBC
bleeding site and clump together to seal off a wound
3. PLATELETS

12. 4. PLASMA “watery” liquid part of the blood
The RBC, WBC, and platelets are floating in this
Makes up 55% of the total volume
Made of water, salt (electrolytes), and protein
FYI: Coconut water can be used (in extreme emergencies) as a substitute for blood plasma

13. FUN BLOOD FACTS:
The average human body holds about 1.25 gallons of blood (if you weigh 160 lbs)
The heart pumps 2,000 gallons of blood through it every day (recycled of course)
It would take 1.2 million female mosquitos all sucking at once to drain the body of blood. Male mosquitos are vegetarian.

14. THE GENETICS OF BLOOD THERE ARE THREE ALLELES FOR BLOOD TYPE: A, B, O
THERE IS A SEPARATE ALLELE FOR THE RH FACTOR, OR RHESUS FACTOR (RH +/-)
YOU INHERIT THESE ALLELES FROM YOUR PARENTS, ONE FROM EACH (2 TOTAL)
TYPE A AND B ARE CODOMINANT AND O IS RECESSIVE TO A AND B
BLOOD TYPING IS A QUICK AND EASY WAY TO RULE-OUT SUSPECTS OF A CRIME

17. it makes no surface molecules at all. NO antigen.
There are antigens on your RBC!
An antigen is a molecule capable of inducing an immune response
The A allele codes for an enzyme that makes the A antigen, The B allele codes for an enzyme that makes the B antigen. The O allele codes for a protein that is not functional;
it makes no surface molecules at all. NO antigen.
Antigens are like the sprinkles on a donut...except they are A or B antigens on a RBC. There are no sprinkles on the RBC if you have type O blood.

18. The Rhesus Factor AKA: Rh factor
This is an antigen that exists on the surface of red blood cells in most people. People who have the Rhesus factor are considered to have a positive (+) blood type, such as A+ or B+. Those who don't are considered to have a negative (-) blood type, such as O- or AB-
Universal donor = can donate to every other type of blood

19. There are two antigens, A and B.
A antigen on the RBC = Type A blood
B antigen on the RBC = Type B blood
Both A and B antigens are present = Type AB blood
Neither antigen present = Type O blood
A + O =
B + O =
A + B =
O + O =

20. NOW, WE GET TO EXPERIMENT ON TYPING BLOOD!

21. What does blood type have to do with forensic science?

24. What do your results infer?
What should investigators do next?

25. Day 2: Forensic Science of Blood Spatter

26. ANALYZING BLOOD SPATTERS
What does the shape of the drop tell us?

28. 3 Types of Blood Evidence
Drip/Passive
Gravity pulls it down
Round and flat...no tails
Transferred
Smeared from a hand or other object
Spatter
High, medium, low velocity

33. EXPERIMENT WITH MAKING DIFFERENT BLOOD SPATTERS