The debate about DNA rages on with Victoria, Australia, temporarily halting the use of DNA in criminal cases because of a problem with interpretation of results after new technology was brought online in September. As a result of the new technology more detailed information was obtained from DNA samples but the statistical models used to interpret the data are now inadequate (Police put ban on DNA evidence). Victoria’s Police Forensics Lab is having a rough time of it lately, with staff refusing to attend court and then being threatened with legal action, a rape case falling over because DNA evidence was contaminated and other issues having a deleterious effect on how the laboratory is running.

Happily, DNA evidence in England now seems to be fairing much better after the suspension of Low Copy Number DNA evidence in 2008 following the spectacular collapse of a major trial against a man charged with one of Northern Ireland’s worse bombings – the Omagh bomb in 1998 (DNA test halted after Omagh case). A man was recently cleared of rape (after he’d been sentenced in 2002 to six years’ imprisonment) as the result of DNA evidence that showed he had not penetrated the victim but that there was evidence of the DNA of three other males on the swabs from the Complainant (Man given six years for rape cleared by new DNA evidence) and another man was convicted after a random “hit” on the DNA database. To me it shows that DNA is one of those areas of forensic science where you can never take your eye off the ball.

Just to throw some petrol on the fire of debate about how long to keep DNA samples on the DNA database if someone hasn’t been charged with a crime, here is an article from the BBC that shows cold case reviews and random hits on the DNA database do occur: Rape conviction ‘backs DNA case’. The Defendant, and now convicted rapist, was arrested in 2001 following an assault for which he was never charged. His DNA profile was uploaded to the UK National DNA Database in 2007 (because of advances in technology) where it scored a hit against an unsolved, outstanding rape case from 1990.

Some will say this is an excellent example of why DNA samples should be retained – what price does society put on solving a rape? On the other hand, some will say that the small number of successful random hits like this are far outweighed by the number of people who consider their civil liberties and human rights are violated by having their DNA retained on a database when they haven’t been proved to have do anything criminal.