The Firkins have always denied any involvement in the murders
Two brothers jailed for the murder of a couple at their home and petrol station business in Cornwall have begun a appeal against their convictions.
Robert and Lee Firkins, from Weston-super-Mare, were jailed for life in 2005 for killing Graham Fisher, 60, and his wife Carol, 53, in November 2003.
The Fishers were repeatedly shot and beaten to death with a sledgehammer at the Perch Garage in Wadebridge.
The appeal hearing in London is due to last for three days.
Mr and Mrs Fisher were killed on Bonfire Night 2003 in their bungalow next to the garage.
During their trial the judge, Mr Justice Owen, said Robert Firkins, 35, and Lee, 33, were "extremely violent and dangerous men" who had "brutally extinguished" the lives of the Fishers.
A central plank of the prosecution case was a former jail cellmate's testimony that Robert Firkins had confessed.
Carol and Graham Fisher were killed on Bonfire Night
But the brothers have consistently denied their involvement in the murders, claiming they were seeing relatives and had visited a local pub.
They were granted an appeal against their conviction at the Court of Appeal in February.