Firkin brothers' murder convictions questioned after witness jailed
The conviction of Robert and Lee Firkins for one of Cornwall's most notorious murders has been cast into doubt, the BBC has learned.
A key witness in the case of the killings of Graham and Carole Fisher has been convicted of working as a hitman and carrying out a murder.
Lawyers for the brothers say that discredits his evidence, and they plan to challenge the convictions.
Mr and Mrs Fisher were shot and beaten to death near Wadebridge in 2003.
Following a lengthy trial at Exeter Crown Court, the Firkins, from Weston-super-Mare, were convicted of the killings and sentenced to life in prison.
The evidence against the brothers - by the admission of senior detectives who investigated the murders - was not strong.
The testimony of a witness who shared a cell with Robert Firkins, and told the police Firkins had confessed to the crime, was central to the trial.
The law forbids the naming of the man - known as Witness Z - to protect him from reprisals. But he told the court Robert Firkins said to him, "Watch Crimewatch and you'll see my work". The BBC programme featured the murder of the Fishers.
Witness Z's evidence was the subject of heated legal argument at the trial, with the defence contending he could not be trusted. But the judge decided it could be put before the jury.
Now the BBC has learned of a court case in which Witness Z was convicted of being hired as a hitman and carrying out a murder.
Lawyers for the Firkins say that undermines his integrity to such an extent his testimony in the trial of the brothers cannot be considered safe and reliable.
They now plan to try to overturn the brothers' convictions.
As the case has already been heard at the Court of Appeal, the lawyers say they will go to the Criminal Cases Review Commission, which investigates alleged miscarriages of justice. It has the power to reinvestigate a case and send it back to the Court of Appeal.
The Firkins have always denied the murders, saying they were seeing relatives and visiting a pub at the time.