1. Blood Spatter Analysis
Presented by
Patricia Nolan Bertino
Bud Bertino

2. Blood Spatter (not splatter)
is the pattern of blood created when blood is deposited on a surface.

3. Blood Detection
Phenolphthalein
Luminol

4. Blood spatter “tells a story”
Where was person located when bleeding?
What direction was blood traveling?
What was the angle of impact?

5. What was the distance between bleeder and the striking surface?
How many events occurred?

6. Is blood spatter evidence consistent with the story told by witness or suspect?

7. Simpson Crime Scene

8. Types of Injury High velocity (gunshot) Medium velocity
(hammer strike)
Low velocity ( drip)

9. Characteristics of a single drop of blood
Spike vs. Satellite

10. Surface variations Smooth (glass)
Slightly raised (floor tiling, varnished wood, fabric)
Rough tile, unvarnished wood

11. Types of Blood Spatter
Passive dripped blood
Transferred hand print
Projected artery bleed
Cast off from a weapon

12. Transferred blood
Footprint Handprint

13. Projected blood
Arterial gush on wall

14. Blood dropped from different heights

15. Patterns of transfer
ceiling
Cast-off from Weapon

16. Direction of travel of blood

17. . 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

18. Point of Convergence 5 ml blood squirted from a
syringe from height of 1 m
Point of Convergence

19. Angle of Impact Origin Height above point of convergence
Distance from point of convergence
Height above point of convergence
Origin
length
width
Angle of impact = arc sin W/L
85
60
45
30

20. Angle of Impact 90 80 70 60 50 40 20 30 10 Path of blood W a
Floor
20
30
10

21. Determine Angle of Impact
Width Length sine arc sine °
14.5° °
Hand-out

22. Point of Convergence

23. Lines of Convergence Draw line through the axis of the main droplet
Start at the end of the blood drop and draw toward the source
Do not draw lines through satellite drops
Draw smallest circle around intersection -marks point of convergence

24. Lines of Convergence
Determine Point of Convergence

25. Don’t over extend the lines!
Draw towards the source of blood

26. Let’s practice!
Floor demo
worksheet

27. Answer Sheet for Lines of Convergence

28. Show Blood animations

29. Practice Paper Blood Droplets
Draw lines of convergence
Determine point of convergence
Measure blood drop width/length
Determine impact angle
Can you determine point of origin?

30. Calculate Point of Origin
Draw lines of convergence
Determine point of convergence
Determine impact angle
Use protractor to determine origin
Floor demo Or
Use Law of Tangents

31. Law of Tangents (TOA)
Opposite Adjacent
Tangent of Angle =
See page 19

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

33. Analyze crime scene pg 21
That’s all folks!