News that scientists have demonstrated the possibility of fabricating DNA is bound to be fodder for the conspiracy theorists among us. “You can just engineer a crime scene,” said the lead author of the new study.
Oh, swell!
Ars Technica has previously reported that there’s not a lot of science to the rest of forensic science. Thankfully, their read of this study suggests all is not lost:
Fortunately, in identifying the problem, the researchers have come up with a solution. DNA inside human cells picks up a chemical modification called methylation; DNA amplified in a test tube doesn’t. It’s possible to determine whether or not a given stretch of DNA has been methylated using standard lab techniques, although these are a bit laborious and time-consuming, and it’s the sort of technique that hasn’t made its way into forensic training yet. Still, testing for methylation in a DNA sample should provide an important quality control on the sample—at least until biologists figure out how to apply methylation in a controlled manner.
It would be tempting to view this as an arms race between the sophistication of fabrication and forensic techniques, but the fact is that your garden variety criminal is unlikely to have the skills and equipment needed to pull a fake off. What it may do is undermine the general confidence in the use of DNA evidence. There’s simply no way of knowing a priori which cases might have a molecular biologist with a vested interest, and therefore which samples need to be tested for tampering. It appears that we’ll need to start testing methylation patterns in every case in order to retain confidence in the general techniques.
In the meantime, the most immediate effect of the paper is that it’s almost certainly set off a spasm of scriptwriting among those responsible for TV whodunnits.
CBS’s Andrew Cohen agrees it’s good for the TV writers. As for our criminal justice system:
“This is potentially huge news in the world of criminal justice, which hasn’t yet even fully had the time to embrace DNA for all of its uses,” said CBS News legal analyst Andrew Cohen. “And I suspect it won’t be long before defense attorneys are using this study to undercut DNA analysis and conclusions in cases all over the country.”
“This is potentially terrible news for prosecutors and police and the military and all sorts of industries that use DNA testing to confirm or find information,” Cohen adds. “As the paper’s author says, ‘You can now just engineer a crime scene.’ Good news for crime dramas on television but not so much to the criminal justice system.”
“It’ll be interesting to see how the legal world reacts to it and whether this study will be embraced or scorned by DNA experts here in the States,” Cohen said. “But you can be sure that before too long DNA evidence in criminal cases all over will be challenged based upon these findings.”