Wednesday, April 1, 2009

What if DNA evidence from a crime scene could tell us what the perpetrator looked like?

That question is the taken from a new post over at the Criminal Justice blog. The post is inspired by an article in the Wall Street Journal, that explains how researchers at Pennsylvania State University performed a study attempting to link specific genes to "phenotypes," or their physical expressions. What this means, then, is that scientists might be able to tell, roughly speaking, a person's physical characteristics by examining their DNA.

As Matt Kelley, the author of the post points out, there is much reason for alarm here. As he says, and as we have noted before, there is cause for concern over "the propensity of criminal justice agencies to use scientific methods before they're ready." He adds, "The U.K. and the Netherlands are already using some form of these tests, as are some U.S. states. Germany has outlawed the practice, along with Indiana, Wyoming and Rhode Island."


The WSJ reports that researchers are able to predict eye color 70-90% of the time and skin color 46% of the time. These numbers aren't strong enough to rely on. Wrongful convictions happen - and real perpetrators get away - when faulty or limited science puts police on the wrong track in those crucial first few days after a crime. I agree that these tests could be helpful in some cases to confirm other evidence, but can we guarantee that genetic composite sketches won't be become simply another form of unreliable forensic science?
The question is when and whether this will become more accurate than other methods of identification, and whether this technique can be used without any illusions of its accuracy. The worry is that juries might hear DNA evidence and assume the practice is close to 100% accurate, rather than the more pitiful, but more truthful, measure of its accuracy.

1 comment:

1American4Justice said...

First let me say your labels always give me a laugh. I read that article too, but "several" genes, that could prove to be very dangerous statistics for wrongful convictions to even remotely put into the hands of the wrong techies, one gene says he is a white person, another gene says with brown eyes..hum narrows down the field of suspects doesn't it?
And from that we have a picture of the average american citizen.

And yes that is me over on Twitter. :o) Green, not Irish, just Olive!