Blood Stain Pattern Analysis:
Blood stain pattern analysis is a form of forensic science that examines blood at crime scenes. From analyzing blood at the crime scene analysts can determine many different things about the crime scene. Some of which include: Where the blood came from
What caused the wounds?
From what direction was the victim wounded?
How were the victim(s) and perpetrator(s) positioned? What movements were made after the bloodshed?
How many potential perpetrators were present?
Does the bloodstain evidence support or refute witness statements?
Because blood behaves according to certain scientific principles, trained bloodstain pattern analysts can examine the blood evidence left behind and draw conclusions as to how the blood may have been shed. From what may appear to be a random distribution of bloodstains at a crime scene, analysts can categorize the stains by gathering information from spatter patterns, transfers, voids and other marks that assist investigators in recreating the sequence of events that occurred after bloodshed. This form of physical evidence requires the analyst to recognize and interpret patterns to determine how those patterns were created. Analysts must obtain a four year degree in forensic science or a Bachelor of Science degree before becoming an analyst. Often elastic string is stretched from blood droplets on the angle that of impact to determine where the blood originated from. Blood splatter can tell the police if the attacker was right or left handed, and how an altercation could have unfolded.

Case Study:
In July 2008 in Chicago Richard Lyons told police that his 9-year old daughter was dead stabbed multiple times in overgrown weeds behind his house. Nearly 2 years later authorities charged it was Lyons himself who killed his daughter Mya. According to law enforcement sources, the case turned on blood-spatter evidence that experts contend proves Mya was stabbed inside her father's van, not in the alley where he said he discovered her body. Lyons had told police that he and his uncle used the van to rush his dying daughter to the hospital. A forensic expert who viewed crime-scene photographs found that Lyons' story to police was "inconsistent with the physical evidence." Found. Blood-spatter evidence was found on the van's back seat, the rear of the front seats as well inside vents, suggesting Mya was struck "from inside the van,'' according to the documents. The dashboard also appeared to have been wiped clean, and blood-spatter was also detected on the shoes worn by Lyons.