Reg Dudley and Robert Maynard, who is still in prison, have always protested their innocence since being convicted in 1977 of the gangland executions of Billy Moseley and Micky Cornwall.
Their convictions, which are already being investigated by the Criminal Cases Review Commission, are seen by their supporters as an appalling miscarriage of justice.
In the absence of any material evidence against them, their imprisonment was secured mainly on the basis of verbal confessions which they denied ever making.
In a Rough Justice television documentary, to be screened tomorrow night on BBC1, Anthony Wild, one of the prosecution witnesses, admits that he fabricated his testimony.
He says that he concocted evidence which included a story that Dudley had boasted about walking into a pub and producing Moseley's head from a plastic bag.
The programme's researchers have also unearthed the other main witness, Sharon Saggs, in whose parents' house Cornwall had been lodging before he was killed. Ms Saggs, who was a young girl at the time, says she has grave doubts about the evidence she gave.
Reg Dudley, who served an extra seven years for protesting his innocence and was released from prison last August, said yesterday: "It is definitely a step forward for us in our attempt to get the case back to the Appeal Court. The two main witnesses are exposed as unreliable and this must make some sort of difference.
"We will always protest our innocence and will never say anything different. We have had the truth drug which shows we were innocent but which the judge didn't allow as evidence. We are willing to take it again at any time, any place, under any conditions. Our one wish is that the police would take it with us at the same time."
Billy Moseley's dismembered remains were washed up along the banks of the river Thames in 1974. A criminal called Ronnie Fright became the main suspect after it was revealed that his wife had been having an affair with Moseley.
When the body of Michael Cornwall, another north London criminal and a close friend of Moseley's, was found buried in woods outside Hatfield with a gunshot wound to his head, police turned their attention to Dudley and Maynard.
The police, led by Commander Bert "Gangbuster" Wickstead, said that the defendants had tortured and killed Moseley because he had called Dudley a "grass", and had later killed Cornwall because he had been having an affair with Dudley's daughter.
The Torso Murders gained further public notoriety after the trial when Moseley's head was discovered in a public lavatory in north London.
Though Maynard is still awaiting parole, Dudley, who now lives in Islington, says that he has reintegrated himself into the community.
He said yesterday: "I have always been a person who can manage in one way or another. I'm lucky in that I can paint and have been selling a few paintings here and there. The council have found me a nice place to live and my friends and family have been unbelievable."
t The Jigsaw Murder will be shown on BBC1 at 10.25pm tomorrow.Reuse content