Blood Spatter

Becky DeJesus

20 Facts

1. Bloodstain Pattern Analysis (BPA) can determine the direction of a blood droplet, minimum number of blows, and type of object used in an attack. (and more)


2. Blood drops that free fall have a sphere shape.


3. A well formed stain is in the shape of an ellipse.


4. The type of surface the blood strikes affects the amount of resulting spatter including the size and appearance of the blood drops.


5. Passive bloodstains are created when gravity is the force acting upon it.


6. A cast off pattern is a bloodstain pattern created when blood is released or thrown from the blood-bearing object in motion.


7. A swipe pattern is the transfer of blood from a moving source onto an unstained surface. Direction of the travel may be determined by the feathered edge.


8. A transfer pattern is a recognizable image of all or a portion of the original surface may be observed in the pattern.


9. High velocity impact can be caused by a gunshot or explosion and result in 1mm size or smaller.


10. Medium velocity impact can be caused by stabbing or blunt force and result in 1-4mm size.


11. A drip pattern results from blood dripping into blood.


12. When blood falls on glass, it results in little or no distortion around the edge.


13. When blood falls on linoleum flooring, scalloping appears on the edge.


14. The point of convergence is the intersection of two different bloodstain paths.


15. The area of convergence is the box formed by the intersection of several stains from opposite sides of the impact pattern.


16. Point (area) of origin is the common point in three dimensional space to which the trajectories of several blood drops can be retraced.


17. BPA provides strong evidence.


18. Bloodstain patterns can be affected by texture of a surface, object used, and direction in which the force is coming from.


19. Projected bloodstains occur when some form of energy has been transferred to a blood source.


20. A flow pattern is a change in the shape and direction of a bloodstain due to the influence of gravity or movement of the object.