Blood spatter analysis is a forensic science involving the study of bloodstain patterns that criminologists use to reconstruct the events of a suspected crime. Analysts examine subtle factors such as the placement, shape and volume of blood to determine the weapon and amount of force used in an attack.
Analysts gather evidence by taking thorough photos and collecting samples for lab testing. They can also set up detailed reconstructions at the crime scene by tying lines of string to trace the spatter angles back to the areas of convergence, or the areas where each blow was initiated. A successful analysis can yield significant information, such as the positions of the victim and attacker, the approximate time when the crime occurred, the number of blows, and whether the attacker was left- or right-handed.