1. Bloodstain Pattern Analysis

2. Summary What is Blood? Determining Distance of Blood
Determining Direction of Blood
Types of Blood Stain Patterns

3. What is Blood?

4. Introduction to Blood

5. Blood Spatter (or splatter)
Blood drops form different shapes and sizes
Blood spatter analysis uses the shapes and sizes to reconstruct the crime scene.

6. Blood drops fall as small spheres
Blood Spatter > Distance
Determining Distance Blood Falls
Blood drops fall as small spheres

7. Determining Distance Blood Falls
Blood Spatter > Distance
Determining Distance Blood Falls
Drops form circle when hitting surface
Size depends on speed of blood drop

8. Determining Distance Blood Falls
Blood Spatter > Distance
Determining Distance Blood Falls
Faster drop = larger diameter (size)
Higher distance = larger diameter
Due to air resistance, speed maxes out at distances above about 7 feet

9. Determining Distance Blood Falls
Blood Spatter > Distance
Determining Distance Blood Falls
However, size of drop also depends on the volume of the drop.
Volume depends on the object blood originated from (needle = small; bat = large).

10. The distance a drop has fallen cannot be measured.
Blood Spatter > Distance
Determining Distance Blood Falls
Since the volume of blood is unknown…
The distance a drop has fallen cannot be measured.

11. Effect of Surface Smooth surface = smooth sphere
Blood Spatter
Effect of Surface
Smooth surface = smooth sphere
Rough surface may cause some splatter

12. Determining Direction of Blood
Blood Spatter > Direction
Determining Direction of Blood
Narrow end of a blood drop will point in the direction of travel.

13. Determining Direction of Blood
Blood Spatter > Direction
Determining Direction of Blood
If more than one drop (from spatter) results, the point of origin can be determined

14. Determining Direction of Blood
Blood Spatter > Direction
Determining Direction of Blood
If more than one drop (from spatter) results, the point of origin can be determined

15. Determining Direction of Blood
Blood Spatter > Direction
Determining Direction of Blood
This is a 2-dimensional point of origin.
It is possible to determine the 3-D point of origin

16. Determining Direction of Blood
Blood Spatter > Direction
Determining Direction of Blood
The angle can be determined mathematically.
Width/Length, then take the inverse sin (sin-1).
This number is the impact angle (90 = perpendicular to surface; <10 at a sharp angle)

17. Blood Spatter > Direction
For each blood drop, a string can be guided back to the point of origin.

18. Blood Spatter
Types of Spatter
Spattered Blood = random distribution of bloodstains that vary in size
Amount of blood and amount of force affect the size of blood spatter.
Can result from gunshot, stabbing, beating

19. Blood Spatter
Spattered Blood can:
Help determine the location of the origin of the blood source.
Help determine the mechanism which created the pattern.

20. Blood Spatter
Spattered Blood
In general, for higher impacts, the pattern is more spread out and the individual stains are smaller.
Low impact = beating
High impact = gunshot

21. Blood Spatter
Types of Spatter
Gunshot Spatter = can result in a mist-like spatter that indicates a gunshot.
Not all gunshots will result in misting.
If misting is present, it is most likely a gunshot.

22. Blood Spatter
Gunshot Spatter
Gunshots result in back spatter (where bullet enters) and forward spatter (where bullet exits).

23. Blood Spatter
Types of Spatter
Beating and Stabbing Spatter = larger individual stains
First blow usually doesn’t result in spatter since there is not yet any exposed blood.

24. Blood Spatter
Types of Spatter
Satellite Spatter = free falling drops of blood that fall onto a spatter pattern.
These drips are usually much larger than impact spatter.
However, blood dripping into blood can create a spatter.

25. Types of Spatter Castoff Pattern = Blood flung off of swinging object.
Blood Spatter
Types of Spatter
Castoff Pattern = Blood flung off of swinging object.
Can reconstruct where assailant and victim were positioned.

26. Blood Spatter
Types of Spatter
Expirated Bloodstain Pattern = Blood can accumulate in lungs, sinuses, and airway. Forcibly exhaled.
Can appear like beating or gunshot pattern.
May be mixed with saliva or nasal secretions.

27. Alteration of bloodstain over time
Blood Spatter
Alteration of bloodstain over time
Blood dries and clots over time.
Difficult to estimate the time the blood exited the body.
Clotted smears can indicate time of movement.