Wednesday, August 19, 2009

DNA – no longer the fail-safe blueprint of crime scene investigations?

This is truly troubling. The fact that DNA evidence can be fabricated for crime scenes takes away the one guaranteed test we had in order to establish criminality (or non-criminality), however infrequently it may be used and followed through even in cases where DNA is available.

Researchers at Nucleix, a lifescience company based in Tel-Aviv, manufactured fake DNA that could potentially be planted at a crime scene. They extracted the DNA to be planted from a small sample tissue, such as a strand of hair or a drop of saliva. They then separated out DNA-free blood cells from donor blood by centrifugation to remove all traces of the donor’s original DNA, and added the "fake" DNA to it. By using DNA profiles from databases, they managed to replicate the double helix, which resembled the structure of DNA from the original hair/saliva sample.

Considering the number of people who are wrongly convicted and spend time behind bars for no reason---apparently there is no consensus on that number---but we can all agree that that number, no matter how small, is unjust and cruel when you are talking about an individual's wasted life. And this is not just in the case of life sentences or death row inmates, since even innocent people who find themselves exonerated after years in prison have a very hard time making a life for themselves in the real world once the stigma of a conviction is attached to them.

This has mostly to do with the lack of standardized compensation policies across the country, including no compensation statutes in 28 states.

To date, 241 innocent people have been exonerated on the basis of DNA evidence thanks to the efforts of the Innocence Project. The judicial system by itself is so unreliable that it does not naturally allow a convicted person rights to DNA testing even if he were to seek it.

However, this is not to say that DNA evidence is absolute, and as some would argue, it cannot---like any other type of evidence---stand alone in a criminal case. Questions have been raised about how unique genetic profiles really are. Moreover, DNA from years-old cases can be damaged, or contaminated.

But DNA evidence is still the most scientifically valid method we have to date to establish proof beyond doubt.

As if to reinforce this, and somewhat comfortingly, the Tel-Aviv lab was able to discern differences between natural and man-made DNA evidence based on the methyl groups that are added to DNA during the natural process of replication.

Thankfully, we haven’t beaten Nature yet. So, let's hope we can use it.