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Blood Spatter Analysis

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1 Blood Spatter Analysis
Serology Blood Spatter Analysis

2 Blood at the Crime Scene
Class evidence: A transfer of blood between victim and suspect or crime scene. Blood typing (A, B, AB, O). Can become individualized by comparing DNA with proper conditions, time and equipment. Courtesy of NYPD

3 Detection of Blood If a substance is discovered at a crime scene that looks like blood, it must first be tested to determine if it is in fact blood. You will then need to determine if the blood is from human or other animal origin. Presumptive test: screening tests to determine the presence of the substance but are not confirmatory.

4 Presumptive Tests - Chemical
Hematest tablets and Hemastix strips: The heme in hemoglobin catalytically breaks down peroxides with the production of oxygen. Oxygen reacts with the benzidine product in the Hematest tablet/Hemastix to turn it blue. False positives: dry bleach residues and some plastics.

5 Hemoglobin Oxygen carrier that gives red blood cells their color. Composed of four globin (protein) chains, each with a heme group.

6 Presumptive Test - Chemical
Kastle-Meyer test: Basted on the catalytic breakdown of peroxides by hemoglobin. Contact of reduced phenolphthalein reagent and hydrogen peroxide with a bloodstain produces a deep pink color. False positives: potatoes and horseradish.

7 Presemptive Test - Chemical
Luminol Test: Very sensitive. Can detect dried and even washed out blood. Makes old blood stains chemiluminesce/glow (emission of light from a chemical reaction). Chemiluminescence reaction A + B [I]* products + light [I]* is an excited state False positives: metals (Cu, Fe, Co), bleach, and sometimes plaster walls.

8 Human vs. Animal Once the stain has been determined as blood, it must then be determined if the blood is from human or other animal origin. Precipitin test: standard method of testing. Extremely sensitive. Used on very diluted or very old blood. Uses an animal serum that contains antibodies specific to human antigens. This causes agglutination with human blood.

9 How it Works – Precipitin Test
A rabbit is injected with human blood. Antibodies are produced to fight the foreign invader. The rabbit serum containing these antibodies is used in the precipitin test. This results in agglutinations. This is similar to a chemical precipitation.

10 Antibodies, Antigens and Antiserum
Antibodies: proteins in the blood or secretory fluids that tag, destroy or neutralize bacteria, viruses, or other harmful toxins, producing an immune response. Antigens: foreign substances in the body that are capable of causing disease. The presence of antigens triggers an immune response, usually the production of antibodies. Antiserum: human or animal serum containing antibodies that are specific for one or more antigens.

11 Serum and Agglutination
Serum: a liquid that separates from clotted blood. Agglutinations: A type of allergic reaction where red blood cells clump together, usually in response to a particular antibody.


13 Serology The laboratory study of body fluids using specific antigen and serum antibody reactions. Karl Landsteiner – Father of Serology 1901 Worked out the ABO blood typing system. 1940 he discovered the rhesus factor (Rh) in blood.

14 Serology - Blood The make up of blood. 1/12 of the body is blood.
Blood is suspended in a liquid called plasma (makes up 55% of blood). Composed of 90% water and 10% metabolites and waste, salts and ions (Na+, Cl-, HCO3-). Solid portion of blood Erythrocytes: red blood cells. Contains hemoglobin; carries O2 from lungs to cells and then CO2 back to lungs. Leukocytes: White blood cells. Primary cells for immunity; produce antibodies. Platelets: create clots by initiating the formation of fibrin. If the clot is removed a pale-yellow, watery fluid is present known as serum.

15 Serology - ABO Characterization
Inexpensive and easy to perform compared to DNA testing. 80% of populations is a secretor (person who’s blood type antigens are found in other body fluids).

16 Serology – ABO Characterization Antigens
Millions of characteristic chemical structures are found on the surface of RBCs. There are two antigens for the ABO system; A&B. Antigens A RBC have A antigens B RBC have B antigens AB RBC have both A & B antigens O RBC have neither.

17 Serology – ABO Characterization Antigens

18 Serology – ABO Characterization Antibodies
Protein manufactured by WBCs which are found in serum. Produced to attack invaders (antigens) that enter the bloodstream. This is the basis for vaccines. If Type A receives blood from type B, antibodies will form to destroy the B antigen. This is done through agglutination.

19 Serology – ABO Characterization Antibodies

20 Serology – ABO Characterization Donor vs. Recipient
If the wrong blood is given it could be fatal.

21 Serology – Rh Factor Sometimes referred to as the D antigen.
Carriers are Rh+ (85% of population) Noncarriers are Rh-

22 Serology – Blood Typing
For unknown blood to be “typed” a drop of blood is added to serum containing known antibodies. Whether there is agglutination determines the blood type in the ABO system.

23 Blood Spatter Analysis
The way in which blood falls, smears, projects and its directionality can help recreate the crime. Also used to prove or disprove the suspects account of what happened.

24 Blood Spatter Analysis Words to Know
Angle of impact Arterial spurting pattern Back spatter Blood spatter analysis Bloodstain Cast-off pattern Contact stain Direction of flight Directionality Directionality angle Draw-back effect Drip pattern Expirated blood Flight path Flow pattern Forward spatter High-velocity impact spatter Impact pattern

25 Blood Spatter Analysis Words to Know
Impact site Low-velocity impact spatter Misting Parent drop Passive drop (bleeding) Point (area) of convergence Point (area) of origin Projected blood pattern Satellite spatter Spatter Spine Swipe pattern Target Transfer or contact pattern Void Wipe pattern

26 Bloodstain Evidence May reveal:
1 Bloodstain Evidence May reveal: Origin(s) of bloodstain Distance of bloodstain from target Direction from which blood impacted Speed with which blood left its source Position of victim & assailant Movement of victim & assailant Number of blows/shots

27 Liquid Blood Physical properties Behaves as a projectile in motion
2 Liquid Blood Physical properties viscosity surface tension specific gravity Behaves as a projectile in motion biology, physics, maths

28 Surface Tension Resistance to penetration & separation
3 Surface Tension Resistance to penetration & separation Surface acts to reduce surface area Smallest SA (surface area) to Volume ratio is offered by sphere

29 Dripping Blood 4 Blood trickles downwards
Blood drop grows until Wt (G) > Surface tension Single drop breaks free (teardrop shape) Surface tension pulls in vertically And horizontally Shape settles into sphere (0.05 ml) Does not break up until impact

30 . . . Drop size 5 Standard drop size 50ul (0.05ml)
Rapid bleeding gives slightly larger drop Shaking/movement casts off smaller drops . . .

31 Free Falling Blood Droplets
8 Free Falling Blood Droplets 0.06 ul 1.1 mm 0.5 to 0.65 m . 2.2 m/s 0.12 ul 1.32 mm 0.84 to 1 m . 3.3 m/s 0.5 ul 2.12 mm 2.4 to 3 m . 4.6 m/s . 50 ul 4.6 mm 7.5 m/s 4.2 to 5.4 m

32 Shape & Size of Bloodspot
9 Shape & Size of Bloodspot Depends mostly on nature of target surface texture (rough or smooth) porous or non porous Size is related to distance fallen, provided: standard 50 ul drop of blood There is little change in spot diameter beyond a fall distance of 1.2 m

33 Height Fallen 10 Single drops of blood falling from fingertip onto smooth cardboard from various heights. No change in diameter beyond 7 ft. Adapted from Introduction to Forensic Sciences, W. Eckert, CRC, 1997

34 Effect of Target Surface
11 Effect of Target Surface . . . Spreads out smoothly ST of spreading edge is broken by irregular surface

35 Experiments with Falling Blood Droplets
12 blood dropper ruler Height Target Surface Fabric (theatre green) rough paper towel paper whiteboard Terazzo floor

36 Single drop of blood falling from various heights (m) onto various surfaces
13 0.5 1 2 3 0.5 1 2 3 Height/Surface smooth floor paper towel fabric

37 Angle of Impact 90 80 70 60 50 40 20 30 10 14
Gravitational dense zone at lower edge 20 30 10 Adapted from Introduction to Forensic Sciences, W. Eckert, CRC, 1997

38 . Wave Cast-off 15 Tail of elongated stain
David Sadler: 15 Wave Cast-off Tail of elongated stain points in direction of travel . Tail of wave cast-off points back to parent drop Parent drop wave cast-off

39 Point of Convergence 16

40 Point of Convergence 17 5 ml blood squirted from a
syringe from height of 1 m Point of Convergence

41 Point of Origin Angle of impact = arc sin W/L 85 60 45 30 1 18
Distance from point of convergence Height above point of convergence Origin length width Angle of impact = arc sin W/L 85 60 45 30

42 Tracing Origin of Bloodspots
19 Tracing Origin of Bloodspots Point of convergence method 2 dimensional image Point of origin method adds 3rd dimension to image In practice: use of string & protractor at scene use of computer at laboratory

43 Blood Spatter Low velocity (5 f/s, 1.5 m/s)
20 Blood Spatter Low velocity (5 f/s, 1.5 m/s) e.g. free-falling drops, cast off from weapon Medium velocity ( f/s, m/s) e.g. baseball bat blows High velocity (>100 f/s, 30 m/s) e.g. gunshot, machinery

44 Low Velocity Blood Spatter
22 Low Velocity Blood Spatter Blood source subjected to LV impact < 5 f/s (1.5 m/s) Spot diameter: mostly mm some smaller, some larger Free-falling drops (gravity only) Cast off from fist, shoe, weapon Dripping Splashing Arterial spurting

45 Cast-off from Weapon First blow causes bleeding
23 Cast-off from Weapon First blow causes bleeding Subsequent blows contaminate weapon with blood Blood is cast-off tangientially to arc of upswing or backswing Pattern & intensity depends on: type of weapon amount of blood adhering to weapon length of arc

46 25 Cast-off from Weapon ceiling

47 Overhead swing with bloodied metal bar
26 Overhead swing with bloodied metal bar

48 Cast-off & medium velocity spatter

49 Cast-off & medium velocity spatter 2
33 Cast-off & medium velocity spatter 2

50 Cast-off Pattern ? Object
34 Cast-off Pattern ? Object

51 Cast-off Pattern from Hand
35 Cast-off Pattern from Hand

52 Cast-off pattern from bloodied hand swung in front of target
36 6” ruler

53 Drip Pattern 37 Free-falling drops dripping into wet blood Large irregular central stain Small round & oval satellite stains . . . . . . . . . . .

54 38 Drip 1: Blood dripping into itself from height of 1 m (8 drops)

55 Blood dripping into itself from height of 1 m (8 drops)

56 40 Dripping onto steps

57 Splash Pattern Volume > 1 ml
41 Volume > 1 ml Subjected to LV impact Thrown Tipped Large central irregular area surrounded by elongated peripheral spatter pattern

58 42 Splash 1 5 ml blood squirted from a syringe from a height of 1 m

59 5 ml blood squirted from a
syringe from a height of 1 m Splash 2 43

60 5 ml blood squirted from a syringe from a height of 1 m
44 Splash 3

61 Splash onto vertical surface
45 Splash onto vertical surface 10 ml blood thrown 1 m onto a vertical target surface 6” ruler

62 Stamping in blood Close-up of heel area
47 Stamping in blood Close-up of heel area

63 48 Blood pool (10 drops) before stamping Stamp 1

64 49 Blood pool (10 drops) after stamping Stamp 2

65 Arterial Spurt Pattern
50 Arterial Spurt Pattern Blood exiting body under arterial pressure Large stains with downward flow on vertical surfaces wave-form of pulsatile flow may be apparent

66 51 spatter Small arterial spurt broken pottery

67 Neck incisions (scene)

68 Neck incisions 53 ‘Hesitation’ injuries Probe in carotid artery
Thyroid cartilage

69 Medium Velocity Blood Spatter
54 Medium Velocity Blood Spatter Blood source subjected to MV impact ( f/s, m/s) Spot diameter: mostly mm Blows with weapon (e.g. baseball bat)

70 55 Medium velocity blood spatter. Point of impact 15 cm in front of vertical target surface 6” ruler

71 High Velocity Blood Spatter
58 High Velocity Blood Spatter Blood source subjected to HV impact > 100 f/s, 30 m/s Fine mist: spot size < 0.1 mm Small mass limits spread to 1 m !Some larger droplets reach further Gunshot back-spatter from entry wound forward spatter from exit wound High speed machinery

72 Gunshot: back& forward spatter
59 Bloodstained foam held just above target surface. Bullet passing L to R just above sheet bullet exits foam Bullet enters foam bullet Back-spatter on entry Forward spatter on exit

73 Gunshot Back Spatter Arises from entrance wound
60 Arises from entrance wound Passes back towards weapon & shooter Seen only at close range of fire Seen on: inside of barrel exterior of weapon hand, arm, chest of shooter

74 Back spatter on steadying hand
61 Back spatter on steadying hand

75 Forward spatter (5 ms after bullet impacted at 1000 f/s)
63 bullet blood soaked target 2.5 cm

76 Gunshot Forward Spatter
62 Gunshot Forward Spatter Arises from exit wound Passes forwards in same direction as shot More copious than back-spatter Can be seen at any range of fire Seen on nearby surfaces, objects, persons especially on wall behind victim

77 Forward spatter (closer view)

78 Forward spatter (closest view)
66 5 mm

79 Wipe Patterns Object moves through a wet bloodstain
67 Wipe Patterns Object moves through a wet bloodstain Feathered edge suggests direction

80 Transfer Patterns Wet, bloodied object contacts a secondary surface
68 Wet, bloodied object contacts a secondary surface Transfer from: hand, fingers shoes, weapon hair Transfer to: walls, ceilings clothing, bedding Produces mirror-image of bloodied object

81 Transfer from hair (hair-swipe) 1

82 Transfer from hair (hair-swipe) 2

83 Flow Patterns Blood flows horizontally & vertically
71 Flow Patterns Blood flows horizontally & vertically Altered by contours, obstacles Often ends in pool

84 Flow pattern 72

85 73 Trapped!

86 Stabbing 1 74

87 Stabbing 2 75

88 76 Blood flow on shirt Horizontally to R side

89 Forward Spatter Contact Stain – footwear Arterial Spurting
Transfer pattern

90 Case Study Sam Sheppard
Early on the morning of July 4th, police received a call from Dr. Sam Sheppard. He reported that his wife, Marilyn, was dead in their bedroom. He explained to police that, the night before, Marilyn had left him on the couch and gone to sleep in the twin bed next to Sam’s. He fell asleep and awoke sometime later, believing he heard his wife calling his name. Going upstairs, he saw Marilyn covered with blood. He checked for her pulse and found none.

91 Sam Sheppard cont’d Sheppard heard a noise below, ran downstairs, and saw someone moving toward the lake. He chased the person across the lawn and down the steps leading to the beach. He struggled with a man 6’3”, middle-aged, with dark bushy hair and a white shirt. Sheppard was choked to unconsciousness. Marilyn had 35 wounds to the head, and blood drenched the walls, door, and bed where she lay. Her face was almost unrecognizable.

92 Sam Sheppard Case Look at the crime scene photos.
Do you believe Sheppard’s story or is he guilty of his wife’s murder?

93 Sam Sheppard Case Sheppard served 10 years in prison before the U.S. Supreme Court ruled that his trial had been tainted. The evidence was reexamined; blood spatters in the bedroom and blood drops throughout the house gave some of the most telling evidence. The expert, Dr. Paul Kirk, concluded that the killer could not have been Sam because the killer was left handed. Dr. Sheppard was right-handed. Video - FSHS

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