Bloodstain Analysis
From Criminal Defense Wiki
A lot of blood is lost during a violent assault. By studying the position, shape and size of the bloodstains, investigators can identify where the attacker stood during the assault, their height, how many times the weapon was used, if the attacker was left/right-handed, and the movements of the victim during the assault. Blood is not easily removed and therefore makes an excellent tool for reconstructing a crime scene.
See Evidence