They make it look so easy on television. In nearly every episode of every crime drama, the crack team of forensic investigators arrives at the crime scene, takes some samples, and voila! Mid-way into the episode, they miraculously have a match, despite the fact that this type of science is still developing and that lab results of this kind move at a snail’s pace.
The reality of crime scene investigation and DNA evidence is far, far, far different.
The first job on the scene is to collect all the DNA evidence and analyze it to even determine how many different people contributed to the jumbled up soup of genetic material. Everyone from the actual killer to the guy in line who sneezed on the victim at Starbucks that morning are in there somewhere. Given the fact that heat, light, and other factors can cause a breakdown in DNA evidence also leads to the confusion of figuring out who’s who.
Unfortunately, experts in the forensics and criminal justice realms have been questioning the validity of DNA evidence for some time. There’s almost no such thing as a 100%, without-a-doubt match, and there’s also no such thing as a legal government standard for how much of a match there has to be before it can be used in court. Too often, though, juries only need to hear that there was a probable DNA match to cause them to overlook other really weak forms of evidence.
Now, researchers who collaborated from Rutgers University and MIT have developed two pieces of software that may change a lot of the way we analyze and view DNA evidence. The first is called NOCit, which stands for number of contributors, and just as the name implies it weeds out the sample based on statistical factors to try to figure out how much of a pool investigators are even working with. The second, MATCHit, compares the sample pool to the suspect’s individual sample in order to determine a ratio of how likely it is that he contributed to the overall mixture, and by how much.
What does remain at this point is the need for solid determination of how this type of evidence will be presented in court, something that experts have been requesting for quite some time. Our ability to gather evidence and analyze it is not lining up yet with our ability to make solid determinations of guilt, and that’s what researchers hope to help correct.