[1] Forbes was found guilty of murder in 1958 after a robbery at a fish factory in Edinburgh in which he killed night watchman Allan Fisher.
Forbes was originally sentenced to the death penalty but it was reduced to life imprisonment.
Only weeks after being released Forbes committed murder again, this time in a pub during a brawl.
He went on to serve 10 years in the Barlinnie special unit with notorious killers such as Jimmy Boyle.
At the age of 68 Forbes was arrested for preparing large quantities of cocaine and cannabis for sale.