Blood spatter evidence has become a well-known part of forensic science and criminal prosecution, especially in homicide cases in Connecticut and across the country. Analysts examine the pattern and formation of blood spatters, spots and drops left behind at the scene of a crime in order to reconstruct the incident. These techniques were pioneered in the late 1900s in Europe and elsewhere although modern technology has enhanced their potential. In some cases, however, questionable use of blood spatter evidence has led to the wrongful conviction and imprisonment of innocent suspects.
Blood evidence, including the direction and size of drops found on the ground, the walls or a person’s clothes, is used to reconstruct the placement of people at a crime scene. While it is commonly used in homicide cases, a 2009 report cast doubt on some of the conclusions drawn by spatter analysts. The report, issued by the National Academy of Science, said that many uses of forensic analysis fail to uphold scientific rigor. In addition, there is no clear credentialing or accreditation mechanism, which can allow doubtful analysts to be cited as experts repeatedly in court. In some cases, rather than working backward from the blood to find the truth, it seemed that analysts used the evidence to fit an existing police theory.
Scientists like physicists say there is much that hard science can contribute to blood spatter analysis, such as fluid dynamics and complex mechanics. However, many analysts do not have scientific training, nor do they regularly apply appropriate algorithms or test their results against a scientific standard.
Forensic evidence is often believed to be infallible, but it can have the same biases as any other prosecution evidence. People charged with a crime may work with a criminal defense attorney to challenge dubious forensic assertions and aim to avoid a conviction.