Bloodstain analysis is a branch of forensic science which can be used as evidence for cases in the court of law. It is simply the study of the patterns and designs formed by blood, which is found at crime scenes. Blood is one of the most common physical evidence that can be found in crime scenes such as murders, suicides, assaults etc. can help investigators understand the type of weapon or instrument used, the possible force used and the impact and also the order of events during the crime. For example, a blood path could indicate that, even after the injury the victim or even the culprit could move around. The place where the action took place can easily be identified. Voids or empty spaces found in stains could indicate something missing which was present during the event is not present in the scene. That could also indicate that a piece or object had been displaced from its original place and placed in another spot in the scene or yet another location or even destroyed. So, most investigators search for blood stains at crime scenes. But at times, bloodstains will not be found, and thus arises the possibility that they may have been erased. In such cases we can find stains using UV light torches or luminol sprays or other effective methods.
Bloodstain pattern formed at the site of crime also depends on the velocity at with it strikes the surface. Depending on the velocity the shape of the spatter varies. Basically the type of spatter formed can be classified into three, which are- low velocity spatter, medium velocity spatter and high velocity spatter. Apart from velocity, the spatter formed is also dependent on the equipment or instrument used to strike. For example, when using the same gun again two types of spatters are often found- forward spatter and back spatter. The caliber of the bullet and also the distance from the victim to person firing the gun are the factors which influence the size of the spatter formed.
BPA (Bloodstain Pattern Analysis) has a significant role in providing reliable information about what happened and what did not happen in the crime scene. It helps in the reconstruction or hypothesis formation of the crime. Blood stains are constituted of liquid plasma and serum and solids like red blood cells white blood cells platelets and proteins. Blood can leave the human body in many forms depending on the type of injury inflicted. It can flow, spray, spurt, gush or just ooze from the wound. The work of a blood stain analyst is to analyze the stain or pattern found at the crime scene. If proper analysis is done questions like “what could have been the murder weapon used?”, “the possible order of events”, “how many blows could have the victim have had?” etc.
All the observations made by analysts take the case closer to solved. Blood analysis is a very useful and important aspect of forensics as it makes investigation much easier for the inspectors. Blood stain analysts determine the form of blood in which it left a person’s body by using accurate techniques. Bloodstains analysis is a simple yet complicated but indeed very useful. Proper analysis can yield answers and make the case a piece of cake to solve.