Bloodstain patterns present on clothing, weapons and at scenes of crime can yield valuable information
Advances in DNA profiling and the acceptance of DNA evidence can lead to new questions - not just whose blood is it, but how did it get there? Blood pattern analysis (BPA) can help with this. BPA looks at the location, size, shape and distribution of bloodstain patterns in association with the underpinning sciences to provide information on the event that resulted in the deposition of these bloodstains. The bloodstain patterns present on clothing, weapons and at scenes of crime can yield valuable information concerning the events that led to the deposition.
Cellmark's BPA scientists use their extensive experience to determine information from BPA which can significantly impact on a case, for example, identifying blood spatter patterns at a scene that would indicate where an individual was attacked, a drip trail to track movements of individuals or a characteristic pattern on a shoe that was caused by kicking. In some cases the absence of blood can also be significant. Our scientists regularly attend court to present the findings and have experience in a wide range of case types from burglary through to complex multiple murder investigations. BPA can be carried out at a crime scene by our specialist scene scientists, or in our laboratories where we also have facilities to reconstruct scenarios and carry out experiments to simulate possible explanations for the blood patterns found.
Our scientists also have expertise in revealing non-visible blood staining using chemical enhancement techniques, for example, where there has been an attempt to clean up a scene or wash clothing. These techniques can also enhance marks in blood, for example footwear marks, wipe marks and drag marks.
Analysis of blood patterns can provide information in a number of ways:
- The bloodstain's point of origin
- The type of 'weapon' used that resulted in the bloodstain
- Was there a single blow or multiple blows?
- The position of victim and/or assailant at a scene when blood was shed
- The likelihood of blood being deposited on an offender
- The reconstruction of the sequence of events to determine whether this supports or contradicts statements given by suspect(s), victim(s) or any witness(es).
- To aid the selection of stains for DNA analysis eg identifying likely blood from the offender amongst the blood of a victim.
Cellmark holds ISO accreditation for BPA at scenes and in the laboratory, for chemical enhancement and provide training services for the Police and other organisations in BPA awareness.