Duffy's history of murder charges
Colin Duffy has been charged with murder three times but on each occasion he has either been cleared or had his conviction quashed.
The 44-year-old was first acquitted of an IRA murder 20 years ago when senior nationalist political figures on both sides of the Irish border rallied to his defence.
But while he publicly declared his innocence at the time, he has been widely seen as a top Provisional IRA man, who left the organisation after it ended violence and cut ties with the Sinn Fein leadership of Gerry Adams and Martin McGuinness, who embraced the peace process.
He was loathed by loyalist paramilitaries who once tried to kill him, hated by Protestants in north Armagh and detested by unionist politicians.
"Many people were scared of him," said one source familiar with the top republican. "He would still be seen as a powerful figure today."
Duffy comes from Lurgan, Co Armagh, a bitterly divided town with Protestants at one end and Catholics at the other, in what was one of the most violent areas at the height of the Troubles.
The Good Friday peace agreement was signed off almost 14 years ago, but the town, only half an hour down the M1 from Belfast, still retains simmering dissident republican resentment to the peace process.
Duffy has been under security force surveillance for virtually all his adult life. As early as 1990 a high-powered video camera carrying Ministry of Defence markings was found trained on his house in Lurgan's Kilwilkie estate.
While Duffy is understood to have briefly continued to back Sinn Fein following the Good Friday peace deal of 1998, he soon rejected the party's direction and became associated with breakaway republicans.