31 August 2012 Last updated at 03:45 ET By Hannah Barnes BBC Radio 4's The Report

Scientists, lawyers and politicians have raised new concerns over the quality of forensic evidence testing - so is the criminal justice system too reliant on lab tests without realising their limitations?

"There was a knock at the door, in the early hours of the morning, saying I was being arrested for murder. I asked, 'what evidence have you got?' and they said they thought it was my DNA.

"I thought 'I'll prove I'm not a suspect' but it didn't pan out that way. DNA has become the magic bullet for the police... they thought it was my DNA, ergo it must be me."

David Butler has every right to be cynical about the use of DNA evidence by the police. He 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

"That was when Alice fell down the hole. Everything went upside down. My whole life changed overnight," he told Radio 4's The Report.

"It was hard. The loneliness was the worst, not speaking to your family. I've led a good life, I've been a good man, and this to me was an absolute horror story."

The police had accused Mr 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.

The DNA sample was only a partial match, of poor quality, and experts at the time said they could neither say that he was guilty nor rule him out.

Original post:
DNA test jailed innocent man for murder