Sean Hoy, 42, forced his way into a flat in Granton Crescent, Edinburgh, and struck Edward Lenyatsa repeatedly with a rolling pin and a knife.
Hoy admitted assaulting Mr Lenyatsa to the danger of his life on 20 April, and was remanded in custody to be sentenced next month at the High Court in Edinburgh.
In 1995, Hoy was jailed for life after being found guilty of murdering David Sproule, 29, in a brawl outside a pub in West Granton Road, Edinburgh.
The victim was stabbed nine times in the neck and suffered 20 blows to the head from punching, kicking and stamping. A second man was convicted of assault.
The Court of Criminal Appeal ruled Hoy had suffered a miscarriage of justice and allowed a retrial. At the second trial, he was again convicted and given a life sentence. Again, he won an appeal and the Crown wanted to stage a third trial but this time the appeal judges refused to sanction a fresh prosecution, and Hoy and was freed.