West Belfast man Tony 'TC' Catney first came to public attention at the tender age of 16 when his murder of another teenager was described by a judge as "cold-blooded".
Student Maurice Knowles (17) from Rathcoole had been duck hunting on the shores of Belfast Lough when he was confronted by Catney who demanded his shotgun.
The young man refused and was shot dead.
Catney was arrested two days later and subsequently convicted of murder.
He served almost two decades in prison and got involved in both the dirty protest and hunger strikes while in the republican wing of the Maze.
Catney was released in 1990 and continued his activity as an IRA man.
In 1994 he opposed the IRA ceasefire.
However, he stayed within the Sinn Fein family and went on to become a key strategist with the political party during one of their biggest electoral rises.
He later fell out with the mainstream republican movement.
In recent years Catney became involved with the Republican Network for Unity, and also campaigned on behalf of dissident republican prisoners including Brendan McConville and John Paul Wootton who were convicted of the 2009 murder of PSNI Constable Steven Carroll in Craigavon.
He denied claims that he was the leader of the Real IRA in Belfast and challenged the PSNI to arrest him if they believed it.
He said: "This is all rubbish. I have my ear to the ground and as far as I am aware the Real IRA doesn't even exist in Belfast apart from one person," said Catney.
"The time is not right for a military campaign, the conditions don't exist. Why then would I involve myself with the Real IRA? It is nonsensical."
In his last interview given in January 2013, Catney described the 2009 murder of Sappers Mark Quinsey and Patrick Azimkar at Massereene Barracks as "executions", as well as describing this and the shooting of David Black and a car bomb that killed PSNI Constable Ronan Kerr as "successful operations".