1. Lesson 6 Blood Spatter Analysis

2. Activity 6.1 Seeing red blood spatters
(Crime Scene Forensics, LLC, New York)

3. Blood spatter 1
Blood spatter 2
What are the differences between the boundaries of the two blood spatters?
What may be the causes of the differences?

4. Activity 6.1 Seeing red blood spatters

5. Activity 6.1 Seeing red blood spatters
Results:
a) Plastic CD case
b) Table cloth
c) Glass plate
d) Sponge

6. Activity 6.1 Seeing red blood spatters
Results:
e) Heat proof mat
f) Bandage
g) Cardboard
h) Newspaper

7. Activity 6.1 Seeing red blood spatters
Interpretation and Deduction:
Shape of Blood Spatter
Description of shape and boundary:
Materials you have used:
Heat proof mat, Table cloth,

8. Activity 6.1 Seeing red blood spatters
Interpretation and Deduction: 1.
Shape of Blood Spatter
Description of shape and boundary:
Round shape,
Smooth and regular boundary
Description of shape and boundary:
Round shape
Jagged & irregular boundary
Materials you have used:
Plastic CD, Glass plate,
Card board
Materials you have used:
Heat proof mat, Table cloth,
Sponge, Bandage,
Newspaper

9. Activity 6.1 Seeing red blood spatters
2. Deduce how the materials of the surface influence the shapes and boundaries of the blood spatters?
A non-porous smooth surface gives a blood spatter with smooth and regular boundary.
A porous rough surface gives a blood spatter with jagged and irregular boundary.
All of the blood spatters are nearly round-shaped. The materials of contact surface do not have a direct influence on the shape of the blood spatter.

10. Activity 6.1 Seeing red blood spatters
3. Based on your classification and deduction, predict what kind of boundaries the blood spatter will have if blood is dropped onto the following surfaces:
Cotton
b) sandy beach
c) the hood of a car
d) floor tile
jagged and irregular boundary
jagged and irregular boundary
smooth and regular boundary
smooth and regular boundary

11. Activity 6.1 Seeing red blood spatters
Conclusion:
Write a few sentences to conclude your findings in this experiment.
Free-falling blood drops tend to form circular blood spatters. The materials of contact surfaces do not influence the shape of the blood spatters.
A non-porous smooth surface gives a blood spatter with smooth and regular boundary.
A porous rough surface gives a blood spatter with jagged and irregular boundary.

12. Activity 6.2 Directionality of Impact
1. To which direction did the blood move? Draw an arrow in the diagram to show its directionality of impact. ?
Source:
(Crime Scene Forensics, LLC, New York)

13. Activity 6.2 Directionality of Impact
Which direction did the blood move? Draw an arrow in the diagram to show its directionality of impact.
Direction of motion
Long axis
Short axis
Satellite spatter
Source:
(Crime Scene Forensics, LLC, New York)

15. Source:http://science. howstuffworks. com/bloodstain-pattern-analysis3
Source: (HowStuffWorks, Inc.)
Notes:
Scallop pattern - bloodstain produced by a single blood droplet characterised by a wave-like, scalloped edge.
Satellite spatters - small droplets of blood projected around a drop of blood upon impact with a surface.
Spines – pointed edge characteristics that radiate away from the centre of a bloodstain; dependent on impact velocity and surface texture.
(Reference:

16. Activity 6.2 Directionality of Impact
2. Identifying the features of blood spatters
Write the names of features in the spaces provided.
Spine
Satellite Spatter
Scallop Pattern

17. Angle of Impact = arcsin (width/length)
(HowStuffWorks, Inc.)

18. Angle of Impact = arcsin (width/length)

20. Activity 6.3 Angle of Impact
1. Mathematical formula of angle of impact
b) Find the angle of impact for the blood spatter in figure 2
sin q = =
q = 30o
Figure 2
Source:
(Crime Scene Forensics, LLC, New York)

21. Activity 6.3 Angle of Impact
2. Finding the angle of impact of a blood spatter
Part I. Making a spatter

22. Activity 6.3 Angle of Impact
2. Finding the angle of impact of a blood spatter Which measurement is correct?
q = 8o
q = 13o

23. Activity 6.3 Angle of Impact
2. Finding the angle of impact of a blood spatter
Part II. Calculating the angle of impact
sin q =
Long axis
Short axis
Blood spatter
Blood spatter
Step 1
Step 1
Step 1
Step 2
Step 2
Step 2
Step 2
Step 3
Step 3
Step 3
Step 3

24. Activity 6.3 Angle of Impact
2. Finding the angle of impact of a blood spatter
Part II. Calculating the angle of impact
Using a venire caliper
Linear match between small scale and main scale at 0.35 mm
Lies between 6 to 7 mm

25. Activity 6.3 Angle of Impact
2. Finding the angle of impact of a blood spatter
Result
Group number 1 2 3 4
Length of short axis / cm
0.52
1.035
1.190
1.570
Length of long axis / cm
3.25
2.140
1.900
1.590
Angle of impact
9.20o
28.92o
38.70o
80.90o
Sketch of spatter

26. Activity 6.4 Case Reconstruction
1. Finding the Point of Origin
If you are given a blood spatter pattern, how can you determine the point of origin?
How far is the point of origin from the target surface?
Source:
(Crime Scene Forensics, LLC, New York)

27. Activity 6.4 Case Reconstruction

28. Activity 6.4 Case Reconstruction

29. Activity 6.4 Case Reconstruction

30. Area of convergence

31. Activity 6.4 Case Reconstruction
1. Finding the Point of Origin
Part I. Making a blood spatter
Video: Preparing bloody sponge
Video: Dropping hammer

32. Activity 6.4 Case Reconstruction
1. Finding the Point of Origin
Part I. Making a blood spatter

33. Activity 6.4 Case Reconstruction
1. Finding the Point of Origin
Part I. Making a blood spatter
Identify some isolated blood spatters with clear edges

34. Activity 6.4 Case Reconstruction
1. Finding the Point of Origin
Part II. Stringing method-Step 1
Draw a long arrow to indicate the direction of origin (opposite to the direction of impact) and mark the angle of impact at each spatter

35. Activity 6.4 Case Reconstruction
1. Finding the Point of Origin
Part II. Stringing method-Step 2

36. Activity 6.4 Case Reconstruction
1. Finding the Point of Origin
Part II. Stringing method-Step 3
Cut off the edge of a protractor below its centre

37. Activity 6.4 Case Reconstruction
1. Finding the Point of Origin
Part II. Stringing method-Step 4
Imagine an oval that encloses the blood spatter
The distance between the pin and the tailing edge of oval is equal to the radius of the pin
The distance between the pin and the front edge of oval is equal to the diameter of the pin
Measure the radius of
the pin

38. Activity 6.4 Case Reconstruction
1. Finding the Point of Origin
Part II. Stringing method-Step 5
The starting point of string is located at the tailing edge of the imaginary oval

39. Activity 6.4 Case Reconstruction
1. Finding the Point of Origin
Part II. Stringing method-Step 6
The centre of protractor aligns with starting point of string
The plane of protractor lies along with the direction of impact
The string is suspended at the angle of impact (54o)

40. Activity 6.4 Case Reconstruction
1. Finding the Point of Origin
Part II. Stringing method-Step 7
Fix the other end of the string on polystyrene board with another thumb pin or adhesive tape

41. Activity 6.4 Case Reconstruction
1. Finding the Point of Origin
Part II. Stringing method-Step 8
Suspend strings from all the blood spatters

42. Activity 6.4 Case Reconstruction
1. Finding the Point of Origin
Part II. Stringing method-Step 9
Locate the point of origin at a position where many strings cross over each other

43. Activity 6.4 Case Reconstruction
1. Finding the Point of Origin
Part II. Stringing method-Step 10 7 10 1 2 3 8 4 9 5 6
Distance of A from vertical surface:
Y = 16 cm
Distance of B from vertical surface:
Y = 9 cm
Height: Z = 14.5 cm
Height: Z = 7.5 cm
Measure the distance of the origin from the vertical and horizontal surfaces

44. Activity 6.4 Case Reconstruction7 10 1 2 3 8 4 9 5 6
Distance from surface: 16 cm
Distance from surface: 9 cm
Height: 14.5 cm
Height: 7.5 cm
1. Finding the Point of Origin
Part II. Stringing method-Step 10
Location of Origin: Two origins were found.
Location of Origin A:
Perpendicular distance from vertical surface: 16 cm
Height: 7.5 cm (the actual position of sponge is 15 cm from the paper)
Location of Origin B:
Perpendicular distance from vertical surface: 9 cm
Height: 14.5 cm

45. Activity 6.4 Case Reconstruction
1. Finding the Point of Origin
Part II. Stringing method-Step 10 7 10 1 2 3 8 4 9 5 6
Distance from surface: 16 cm
Distance from surface: 9 cm
Height: 14.5 cm
Height: 7.5 cm
Explanation:
When hammer hit the sponge, a primary origin was produced to form the blood spatters at labels 4, 5, 6, 8, 9.
The hammer might swing in air to produce a second origin to form the blood spatters at labels 1, 2, 3, 7, 10

46. Activity 6.4 Case Reconstruction7 10 1 2 3 8 4 9 5 6
Distance from surface: 16 cm
Distance from surface: 9 cm
Height: 14.5 cm
Height: 7.5 cm
1. Finding the Point of Origin
Part II. Stringing method-Step 10
Conclusion:
The point of origin of a blood spatter
had been found by using stringing technique.
The directionality and angle of impact of each blood spatter were determined. Then a string was suspended from each spatter according to the calculated information.
The position where most strings were crossing each other indicated the position of the origin.
In this experiment, two origins were found. The first origin was the primary source of impact. The second origin would be caused by swinging of hammer in air.

47. Activity 6.4 Case Reconstruction7 10 1 2 3 8 4 9 5 6
Distance from surface: 16 cm
Distance from surface: 9 cm
Height: 14.5 cm
Height: 7.5 cm
1. Finding the Point of Origin
Part II. Reflection
What kinds of human qualities or attributes are essential for successful achievement of case
reconstruction?
Knowledgeable in forensic science and other fields of science
Adopt interdisciplinary thinking
Objective, evidence-based
Well-organized, systematic
Attentive, patient, having keen observation
Logical, flexible and creative minded
Frequently reviewing and checking for mistakes
Ready for challenges and failures

48.
Source: HemoSpat

49. Activity 6.4 Case Reconstruction
2. Using computer programs
HemoSpat Demo

50. Activity 6.4 Case Reconstruction
2. Using computer programs
HemoSpat Demo

51. Activity 6.4 Case Reconstruction
2. Using computer programs
HemoSpat Demo

52. Activity 6.4 Case Reconstruction
2. Using computer programs
HemoSpat Demo

53. Activity 6.4 Case Reconstruction
2. Using computer programs
HemoSpat Demo

54. Activity 6.4 Case Reconstruction
2. Using computer programs
HemoSpat Demo