Hugh Pickens writes writes "Thanks to fast-paced television crime shows such as CSI: Crime Scene Investigation, we have come to regard DNA evidence as uncontestable. But BBC reports that David Butler has every right to be cynical about the use of DNA evidence by the police. Butler spent eight months in prison, on remand, facing murder charges after his DNA was allegedly found on the victim. ""I think in the current climate [DNA] has made police lazy," says Butler. "It doesn't matter how many times someone like me writes to them, imploring they look at the evidence... they put every hope they had in the DNA result."" The police had accused Butler of murdering a woman, Anne Marie Foy, in 2005 — his DNA sample was on record after he had willingly given it to them as part of an investigation into a burglary at his mother's home some years earlier. But Butler has a rare skin condition, which means he sheds flakes of skin, leaving behind much larger traces of DNA than the average person and Butler worked as a taxi driver, and so it was possible for his DNA to be transferred from his taxi via money or another person, onto the murder victim. The case eventually went to trial and Butler was acquitted after CCTV evidence allegedly placing Butler in the area where the murder took place was disproved. Professor Allan Jamieson, head of the Glasgow-based Forensic Institute, has become a familiar thorn in the side of prosecutors seeking to rely on DNA evidence and has appeared as an expert witness for the defense in several important DNA-centered trials, most notably that of Sean Hoey, who was cleared of carrying out the 1998 Omagh bombing which killed 29 people. Jamieson’s main concern about the growing use of DNA in court cases is that a number of important factors -human error, contamination, simple accident — can suggest guilt where there is none. “Does anyone realize how easy it is to leave a couple of cells of your DNA somewhere?” says Jamieson. “You could shake my hand and I could put that hand down hundreds of miles away and leave your cells behind. In many cases, the question is not ‘Is it my DNA?’, but ‘How did it get there?’”"