Evidence has emerged which suggests that a key witness in the Arlene Fraser murder trial lied.
Nat Fraser was jailed for life for the murder of his wife Arlene
Elgin farmer Hector Dick gave evidence against Mrs Fraser's husband Nat, who was found guilty, after his own murder charge was dropped.
BBC Scotland's Frontline team has found papers which it said show key witness Mr Dick lied in court about the disposal of a car used in the killing.
The disclosure has cast doubt on the safety of Nat Fraser's conviction.
Nat Fraser has been appealing against his conviction for the 1998 murder. His wife's body has never been found.
Mrs Fraser disappeared from her home in Elgin, shortly after waving her two children off to school.
In 2003, her husband was found guilty of hiring a hitman to kill his wife and dispose of her remains. His two co-accused, one of whom was Hector Dick, walked free.
Giving evidence for the Crown, Mr Dick said he dumped a car he had bought for Nat Fraser, along with a stainless steel tank, at a scrapyard in Elgin soon after Mrs Fraser disappeared.
However, Frontline said the owner of the yard, Douglas Williamson, was adamant that the flattened remains of the car were not discarded at his premises.
Mr Williamson, who was never called as a witness, has also produced receipts which he said proved that the tank was dumped there - two years before the Elgin mother went missing.
Mr Dick disputed that version of events and said he has evidence to back up his story.
At Nat Fraser's trial, Judge Lord Mackay branded him "evil" and ruled he should spend a minimum of 25 years in jail before being considered for release.
However, in May, the Court of Appeal ruled that he had grounds to appeal.
Arlene Fraser Murder Trial: The Missing Evidence will be transmitted on BBC One Scotland at 1900 BST on Wednesday, 19 October.