The public have been warned not to approach a robber on the run who once beat a man to death with a hammer.
James Casey, 50, failed to return to Castle Huntly open prison near Dundeefollowing a period of day release on Thursday.
He was nearing the end of a 14-year sentence for robbing a West Lothian Post Office in 2002.
That offence came just months after he had been released from prison after receiving a life sentence for the brutal murder of an Invergordon social club boss in 1990.
Ian MacBeth, 37, was attacked outside the Invergordon Social and Recreational Club in September 1990.
Casey and his accomplice George McNairn lay in wait for the father-of-two for four nights before launching their attack.
Wearing stocking masks and heavy woollen socks over their shoes to cover the sound of their approach, they struck him with a mason’s hammer and stole £1,260 in takings.
They then bundled Mr Macbeth into his own car and drove to Tulloch Wood near Kindacre.
There he was attacked again, this time with a wooden sign.
The final blow broke Mr MacBeth’s neck. It was later discovered he had suffered three skull fractures during the frenzied assault.
The robbers then handcuffed their victim to a tree, gagged him with his own socks and left the scene.
From there they got a lift to Inverness and took the train to London.
When the men were caught they each blamed the other for the murder.
The jury believed McNairn, who was cleared of murder and jailed for 18 months for robbery in 1991.
Casey was given a life sentence and told he must service 11 years.
He was jailed again in 2002, just months after his release, for robbing the post office.
Casey denied the murder for 20 years but the Court of Criminal Appeal in Edinburgh threw out his claim that he had only played a minor part in the attack in 2011.
He claimed improved DNA tests would show McNairn was the killer.
Police Scotland said they believed Casey may have returned to the Inverness area after absconding this week.
He is described as being 5ft 8in with receding hair and brown eyes.
When last seen he was wearing a blue coat, black hooded top, blue jeans and brown walking boots.
Anyone with information on his whereabouts should contact Police Scotland on 101 or call Crimestoppers anonymously on 0800 555 111.