1. Chapter 10 Blood “There will be blood tonight!” —Inigo Montoya, in The Princess Bride

2. Chapter 101 Blood @ the Crime Scene  Location, distribution, pattern of blood, and blood stains can help reconstruct the crime  Can be used as class or individual evidence

3. Chapter 102 Serology Serology – examination and analysis of body fluids A forensic serologist may analyze a variety of body fluids including saliva, semen, urine, and blood

4. Chapter 103 Blood Characteristics  Plasma is the fluid portion of the blood (55%)  Cells (45%)  Erythrocytes = RBCs; responsible for oxygen distribution  Leukocytes = WBCs; responsible for fighting infection  Thrombocytes = platelets; responsible for blood clotting

5. Chapter 104 Human Blood  RBCs are most numerous; 5 to 6 million per mm 3  WBCs are larger and less numerous; 5 to 10,000 per mm 3  Platelets are tiny, cellular fragments; 150,000 to 350,000 per mm 3

6. Chapter 10 Antibody-Antigen Connection  WBCs manufacture proteins called antibodies  Antibodies fight foreign substances; attack antigens  Antigens – invaders (i.e. bacteria, viruses, foreign substances)  Antibody binds to antigen  WBCs destroy the antibody-coated antigen 5

7. Chapter 106 Historical Perspective of Blood Typing Around 1900, Karl Landsteiner discovered blood types:  Blood type – determined by the type of antigen present on surface of RBCs  ABO blood groups—based on having an A, B, both or no antigens on red blood cells

8. Chapter 107 Historical Perspective of Blood Typing In 1940, Landsteiner and Weiner discovered the Rh factor in the blood of the Rhesus monkey  Rh factor – antigen sometimes present on surface of RBCs  Have it = Rh-positive (Rh + )  Don’t have it = Rh-negative (Rh - )

9. Chapter 10 Blood Terminology  Agglutination—clumping of red blood cells  Results when different blood types are mixed together

10. Chapter 10Kendall/Hunt Publishing Company9 Blood Groups Type Antigen Antibody Can Give Blood To Can Get Blood From A B AB O A B A and B Neither A nor B B A Neither A nor B A and B A, ABO, A B, ABO, B AB A, B, O, AB O

11. Chapter 1010 Population Distribution of Blood Types in the U.S. TypePercent O A B AB 45 40 11 4

12. Chapter 1011 Unknown Stain at a Scene Questions to be answered:  Is it blood?  Is it human blood?

13. Chapter 1012 Tests for Blood  Kastle-Meyer color test—a mixture of phenolphthalein and hydrogen peroxide; 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. Chapter 1013 Human vs Animal Blood  Microscopic observation  Precipitin test:  Human blood injected into rabbit  Rabbit forms antibodies against human blood  Rabbit’s blood extracted and placed on blood sample  Sample will react if human blood is present

15. Chapter 1014 Animal Blood Larger nucleic RBCs Frog Blood

16. Chapter 1015 Unknown Stain at a Scene If blood is human:  Whose is it?  Determine blood type, alcohol content, drugs present  Determine the method(s) in which blood may have been deposited

17. Chapter 1016 Blood Pattern Reconstruction Scene Pattern Reconstruction 1. Stain condition 2. Pattern 3. Distribution 4. Location 5. Directionality Lab Results Reconstruction 1. Genetic marker typing 2. Age Determination 3. Source Determination 4. Race Determination 5. Sex Determination

18. Chapter 10 Blood Spatter Evidence  Deals with the physical properties of blood and the patterns produced under different conditions  Blood, as a fluid, follows the laws of physics

19. Chapter 1018 Blood Droplet Characteristics  A blood droplet will remain spherical in space until it collides with a surface  On impact, a bloodstain is formed  A droplet falling from the same height, hitting the same surface at the same angle, will produce a stain with the same basic shape

20. Chapter 1019 Conditions Affecting Shape of Blood Droplet  Size of the droplet  Angle of impact  Velocity at which the blood droplet left its origin  Height  Texture of the target surface  On clean glass or plastic—droplet will have smooth outside edges  On a rough surface—will produce scalloping on the edges

21. Chapter 1020 Blood Spatter Interpretation  The distance between the target surface and the origin of blood  The point(s) of origin of the blood  Movement and direction of a person or an object  The number of blows, shots, etc. causing the bloodshed and/or the dispersal of blood.

22. Chapter 1021 Blood Spatter Interpretation  Type and direction of impact that produced the bloodshed  The position of the victim and/or object during bloodshed  Movement of the victim and/or object after bloodshed

23. Chapter 1022 Bloodstain Terminology  Angle of impact—angle at which blood strikes a target surface  Bloodstain transfer—when a bloody object comes into contact with a surface and leaves a patterned blood image on the surface  Backspatter—blood that is directed back toward the source of energy  Cast-off—blood that is thrown from an object in motion

24. Chapter 1023 Bloodstain Terminology  Contact stain—blood deposited from direct contact b/w 2 surfaces (1 of which is bloody)  Transfer—a bloodstain pattern is created when a wet, bloody surface comes in contact with a 2 nd surface (creating a recognizable image)  Swipe—wet blood is transferred to a surface which did not have blood on it  Wipe—a non-blood bearing object moves through a wet bloodstain, altering the appearance of the original stain

25. Chapter 1024

26. Chapter 1025 Bloodstain Terminology  Directionality—relates to the direction a drop of blood traveled in space from its point of origin  Terminal velocity—the greatest speed to which a free falling drop of blood can accelerate in air High velocity—usually 100 feet per second; gives a fine mist appearance Medium velocity—5 to 25 feet per second Low velocity—5 feet per second or less

27. Chapter 1026

28. Chapter 1027 Bloodstain Patterns The shape of a blood drop:  Round—if it falls straight down at a 90 degree angle  Elliptical—blood droplets elongate as the angle decreases from 90 to 0 degrees

29. Chapter 1028 Patterns  Measure width and length of drop  Sine = width = 9mm length 18mm 9 divided by 18 = 0.500  Sin -1 0.500 = 30 degree angle of impact

30. Chapter 1029 Impact  The more acute (smaller) the angle of impact, the more elongated the stain  90 degree angles are perfectly round drops  80 degree angles take on a more elliptical shape  At about 30 degrees the stain will begin to produce a tail

31. Chapter 10 Wave Cast-off. Parent drop wave cast-off Tail of wave cast-off points back to parent drop Tail of elongated stain points in direction of travel

32. Chapter 1031 Bloodstain Patterns  Hard surface = less the blood drop will break apart  Soft surface = more a blood drop will break apart  The pointed end of the blood stain faces away from the point of origin

33. Chapter 1032 Area of Intersection and Convergence Draw lines from various blood droplets to point where they intersect (converge) Point of origin – where the “blow” occurred

34. Chapter 1033 Blood Evidence  Blood stain patterns = circumstantial evidence in court  Arguable points:  Direction of travel  Height of the perpetrator  Position of the victim  Left/right hand  Whether the body was moved