LONDON (Reuters) - The family of James Hanratty, one of the last men hanged in Britain, plan a fresh bid to overturn his 1962 conviction for a notorious roadside murder and rape.
Doubts about Hanratty's conviction arose soon after his execution and played a significant role in Britain's abolition of the death penalty three years later.
His relatives believe DNA evidence that undermined an appeal eight years ago was contaminated and want judges to revisit the case.
"We are talking about a crime scene sample being in the same folder as all Jimmy's fibres, blood samples, hairs -- all in the same folder," Hanratty's brother Michael told BBC radio.
Hanratty, 25, a small-time thief, protested until his hanging that he was not guilty of one of Britain's most infamous crimes and urged his family to clear his name.
"The day before the execution, his last words were 'Mick, I am completely innocent. Look after Mum and Dad. Keep your eye on the newspapers -- this in years to come will come out'," his brother added.
Hanratty was hanged on April 4, 1962, for what became known as the "A6 Murder" after a road in Bedfordshire by the side of which 36-year-old scientist Michael Gregsten was shot dead.
His 22-year-old mistress, Valerie Storie, was raped, shot and left paralysed for life.
The case was re-examined in 2002 but the Appeal Court refused to clear Hanratty, saying DNA samples taken from his exhumed remains confirmed his guilt.
Lawyer Geoffrey Bindman told the Daily Mail that Hanratty's family now wanted to send the case for another appeal.
"Since all the other evidence against Hanratty had been discredited, the only basis on which the Court of Appeal rejected the appeal was the DNA evidence, so if we can discredit that then Hanratty should be exonerated," Bindman said.
A request for a fresh appeal would be sent to the Criminal Cases Review Commission early in the new year, the BBC reported.
During Hanratty's 21-day trial -- then the longest murder trial in British history -- the prosecution alleged he had surprised the lovers in a cornfield before forcing them to drive to Deadman's Hill, and shooting them.
But at the 2002 Appeal Court hearing it was argued Hanratty's conviction was "fatally flawed" due to "extensive and inexcusable non-disclosure" by police handling the case and "malpractice on a substantial scale" of a detective.
However, Appeal Court judge Lord Chief Justice Woolf said there was no dispute that DNA from Hanratty was found on a fragment from Storey's underwear. She had identified Hanratty as the man who shot her and killed Gregsten.
Editing by Steve Addison