Bloodstain pattern analysis is defined as the examination of shapes, locations and distribution patterns of bloodstains, in order to provide an interpretation of the physical events which gave rise to their origin. Bloodstain patterns can help investigators understand the actions and motions of the victim and the suspect throughout the crime scene. The patterns may indicate that a crime first thought of as a suicide was in fact a homicide. The analysis of bloodstain patterns is a complicated discipline and requires much experience with many different situations to learn to do an accurate reading. The bloodstain pattern analysis plays a very important role in the reconstruction of many crime scenes. .
The various types of bloodstains account for how the blood was projected from the body. Blood may be dripped out of the body, sprayed from an artery, oozed out through a large wound or flung off a weapon that has struck another person. Through bloodstain pattern analysis, analysts can determine, among other things, the type of injuries received, the order in which the injuries were received, whose blood is present at the scene, the types of weapons used in the crime, whether or not the victim was in motion at the time the injury was inflicted, and how far the blood droplets fell before hitting the surface upon which they were found. The shape of drops of blood can reveal all sorts of significant information. Some experienced analysts are even able to use some of the bloodstains to recreate the event. .
Three main categories of bloodstain patterns are transfer, passive and projected bloodstains. Transfer bloodstains are when wet bloody surfaces come into contact with another source, such as a bloody handprint or shoe print. Subcategories of transfer bloodstains would be contact bleeding, swipe or smear, wipe and smudge. Passive bloodstains are only drops of blood created by gravity acting alone.
