1. Blood & Blood Spatter Catalyst - Tuesday, 01.06.2009
List the types of evidence blood can be classified as and WHY.

2. 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
All Rights Reserved South-Western / Cengage Learning © 2009
Forensic Science: Fundamentals & Investigations, Chapter 8

3. Introduction and History
Blood typing can provide class evidence; whereas DNA profiling can provide individual evidence.
A blood splatter pattern can give information about the truthfulness of an account by a witness or a suspect.
It also can provide information about the origin of the blood, the angle and velocity of impact, and type of weapon used.
Our understanding of blood began in ancient times and continues to grow today.
Forensic Science: Fundamentals & Investigations, Chapter 8

4. (brief) History of Blood
2500 BCE – Egypt – bloodletting to “cure” disease
1659 – Leeuwenhoek viewed blood cells w/ microscrope
1901 – Landsteiner – three major blood types (A,B, O)
Forensic Science: Fundamentals & Investigations, Chapter 8

5. Blood Function
Transport of substances (O2, CO2, nutrients, waste, heat, hormones)
Regulation (pH, temperature, hydration)
Defense (blood loss, microbes, toxins)
Forensic Science: Fundamentals & Investigations, Chapter 8

6. Composition of Blood
Whole blood carries cells and plasma—the fluid with hormones, clotting factors, and nutrients.
Shown above respectively:
Red blood cells (RBC / erythrocytes) carry oxygen to the body’s cells and carbon dioxide away.
White blood cells (WBC / leukocytes) fight disease and foreign invaders and, alone, contain cell nuclei.
Platelets aid in blood clotting and the repair of damaged blood vessels.

7. How scientists know…
Forensic Science: Fundamentals & Investigations, Chapter 8

8. These % are important for later on.
Blood Typing
42% % 3% %
of the population in the United States
(of which 85% is Rh+)
Cell surface proteins (proteins on cell/plasma membrane) determine blood types
Other proteins can distinguish blood (Rh, MN, etc.)
Blood typing quicker / cheaper than DNA profiling.

9. Blood Typing
Antibodies are proteins secreted by WBCs that attach to antigens to destroy them.
Antigens are molecules or cells attached to RBC that react to antibodies.
Blood Type
Antigens
Antibodies A B AB
A, B O
none
Forensic Science: Fundamentals & Investigations, Chapter 8

10. Blood Typing
Antibodies are proteins secreted by WBCs that attach to antigens to destroy them.
Antigens are molecules or cells attached to RBC that react to antibodies.
Blood Type
Antigens
Antibodies A B AB
A, B
none O
Forensic Science: Fundamentals & Investigations, Chapter 8

11. Blood Typing If you mix A blood & B blood, what will happen?
Forensic Science: Fundamentals & Investigations, Chapter 8

12. Blood Typing
Agglutination – clumping of RBCs - Foreign blood type reacts w/ regular blood type & an immune response occurs (agglutination)
Forensic Science: Fundamentals & Investigations, Chapter 8

13. Blood typing
How could you use agglutination to help you blood type accurately?
Brain storm with your groups.
Forensic Science: Fundamentals & Investigations, Chapter 8

14. Blood typing
Place unknown blood on a surface with different antibodies (Anti-A, Anti-B, and Anti-D) - Anti-D is to test the Rh factor (+/-)
Blood Type
Anti-A
Anti-B
Anti-D
Control
Forensic Science: Fundamentals & Investigations, Chapter 8

15. Blood Typing Homework (Tues)
Read pp
In your notebooks, draw what the blood typing test would look like for each of the following blood types:
A-, B+, B-, AB+, AB-, O+, O-, and an invalid test.
Blood Type
Anti-A
Anti-B
Anti-D
Control
Forensic Science: Fundamentals & Investigations, Chapter 8

16. Blood Analysis – Catalyst – 01.07.2009
Take out your blood typing Homework problems!
In your notebook, answer the following questions: 1. What is the probability of throwing dice and getting two sixes? 2. What percentage of the population should have A+ blood? (Look at your notes for actual %s)
Forensic Science: Fundamentals & Investigations, Chapter 8

17. Bloodtyping HW Answers
Forensic Science: Fundamentals & Investigations, Chapter 8

18. Blood Typing—Probability and Blood Types
Given the frequency of different genes within a population, it is possible to determine the probability that a particular blood type will appear in a particular population.
To determine the probability of two separate events, it is necessary to multiply their individual probabilities.
By identifying the additional proteins in the blood evidence sample, investigators can limit the size of a suspect population and help identify a suspect.
Forensic Science: Fundamentals & Investigations, Chapter 8

19. Blood Analysis – Catalyst – 01.07.2009
1. What is the probability of throwing dice and getting two sixes?
2. What percentage of the population should have A+ blood?
Forensic Science: Fundamentals & Investigations, Chapter 8

20. Blood Analysis – Catalyst – 01.07.2009
1. What is the probability of throwing dice and getting two sixes? 1/6 chance for getting a /6 x 1/6 = 1/36 chance for 2 sixes.
2. What percentage of the population should have A+ blood?
Forensic Science: Fundamentals & Investigations, Chapter 8

21. Blood Analysis – Catalyst – 01.07.2009
1. What is the probability of throwing dice and getting two sixes? 1/6 chance for getting a /6 x 1/6 = 1/36 chance for 2 sixes. 2. What percentage of the population should have A+ blood?
A blood = 0.42; Rh+ blood = 0.85
Forensic Science: Fundamentals & Investigations, Chapter 8

22. Blood Analysis – Catalyst – 01.07.2009
1. What is the probability of throwing dice and getting two sixes? 1/6 chance for getting a /6 x 1/6 = 1/36 chance for 2 sixes. 2. What percentage of the population should have A+ blood?
A blood = 0.42; Rh+ blood = 0.85
A+ blood = 0.42 x 0.85 = = 35.7%
Forensic Science: Fundamentals & Investigations, Chapter 8

23. Do not wear light colored clothing tomorrow! Bring old newspapers!
Blood Analysis
1. Find the probabilities of each of the blood types from the blood tests. 2. Find the probabilities of each of the following blood-type proteins (use p.201 to help you with %s): i. Type O+,MN ii. Type A-,MM iii. Type AB+, NN iv. Type B-, MN v. Type O-, MM vi. Type B+, NN 3. Read Activity 8-3 pp and write/draw short summary of the lab.

24. Thursday, 01.08.2009 PUT THE ANSWERS TO THE HOMEWORK HERE.
Forensic Science: Fundamentals & Investigations, Chapter 8

25. Blood Drop Height Lab (01.08.2009)
Prepare references cards for blood spatter from various heights.
Compare and contrast various height blood spatter patterns.
Forensic Science: Fundamentals & Investigations, Chapter 8

26. Blood Drop Height Lab (01.08.2009)
Materials Needed: - Simulated Blood - 12 five-by-eight-inch index cards - Meter Sticks - Smaller rulers - Newspapers
Forensic Science: Fundamentals & Investigations, Chapter 8

27. Blood Drop Height Lab (01.08.2009)
Two trials for each of the following heights: 25cm, 50cm, 100cm, 150cm, 200cm, 250cm
Put your data in a data table like on pp.227
Create a bar graph/histogram comparing average diameter vs. height of blood drop (label the axes appropriately!).
Answer the analysis questions on p.228 – including the further study questions (you may have to look up this information).
Forensic Science: Fundamentals & Investigations, Chapter 8

28. Friday
Catalyst:
What can a blood spatter pattern tell you about a crime scene?
Forensic Science: Fundamentals & Investigations, Chapter 8

29. 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.
Forensic Science: Fundamentals & Investigations, Chapter 8

30. Blood Splatter
In 1939 the meaning of the splatter pattern was first analyzed.
When a wound is inflicted, a blood splatter pattern may be created.
It takes a grouping of blood stains to make a blood splatter pattern.
The pattern can help to reconstruct the events surrounding a shooting, stabbing, or beating.
Forensic Science: Fundamentals & Investigations, Chapter 8

31. Blood Splatter Analysis
When blood falls from a height or at a high velocity, it can overcome its natural cohesiveness and form satellite droplets.
When it falls onto a less-than-smooth surface, it can form spiking patterns around the drops.
Forensic Science: Fundamentals & Investigations, Chapter 8

32. Blood Splatter Analysis—Six Patterns
Describe each of these based on the images above:
a. passive drops
b. arterial gushes
c. splashes
d. smears
e. trails
f. pools
Forensic Science: Fundamentals & Investigations, Chapter 8

33. 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?
Forensic Science: Fundamentals & Investigations, Chapter 8

34. Blood Splatter Analysis—Directionality
The shape of blood drops gives an idea of the direction of impact.
How will the point of impact compare with the rest of a blood pattern?
Forensic Science: Fundamentals & Investigations, Chapter 8

35. Blood Splatter Analysis—Location of the Origin of the Blood
Lines of convergence
Draw straight lines down the axis of the blood splatters.
Where the lines converge, the blood originated.
Forensic Science: Fundamentals & Investigations, Chapter 8

36. Crime Scene Investigation of Blood
Search for blood evidence.
If any is discovered, process it determining:
Whether the evidence is blood.
Whether the blood is human.
The blood type.
Interpret the findings:
See if the blood type matches a suspect.
If it does not, exclude that suspect.
If it does, decide if DNA profiling is needed.
Forensic Science: Fundamentals & Investigations, Chapter 8