Denis Donaldson (56) who was found shot dead today was once a key part of Sinn Fein in Northern Ireland.
But as he later admitted, for 20 years he was also working for British intelligence a fact that seems inextricably linked with his death.
This led to him being ostracised from his former party colleagues and explains why at the time of his death he was living in virtual squalor at a near derelict cottage without electricity or running water in the days running up to his death - far away from his comfortable terraced home in republican west Belfast, which has remained empty since he fled in December.
The west Belfast resident and one time friend of hunger striker Bobby Sands was a key aide to Gerry Adams who helped ensure Sinn Féin's Stormont machine ran smoothly.
Born in the staunch republican enclave of Short Strand in mainly loyalist east Belfast in 1950, his commitment to armed struggle and a prison sentence in the early 1970s with hunger striker Bobby Sands, prepared Mr Donaldson for key, trusted positions under the leadership of Gerry Adams.
His arrest in October 2002 along with his son-in-law and a civil servant, became known as Stormontgate - a republican spy ring at the heart of government caused the collapse of the devolved power-sharing administration and suspension of the Assembly.
Mr Donaldson was arrested after police raided Sinn Fein's offices at Stormont as part of an investigation into republican intelligence gathering on October 2002. During a High Court bail application it was claimed he had risked his life to help free Beirut hostage Brian Keenan.
But far from being a republican spying on the Government, he was a British agent working at the heart of Sinn Fein.
Mr Donaldson claimed last December he had been turned in a moment of weakness. The announcement sent shockwaves through the republican movement.
"Since then I have worked for British intelligence and the RUC/PSNI Special Branch. Over that period I was paid money," Mr Donaldson said in a statement.
He said he "was not involved in any republican spy ring in Stormont. The so-called Stormontgate affair was a scam and a fiction, it never existed, it was created by Special Branch.
"I deeply regret my activities with British intelligence and RUC PSNI special branch. I apologise to anyone who has suffered as a result of my activities as well as to my former comrades and especially to my family who have become victims in all of this."
The British and Irish governments were set to unveil their blueprint on the way forward in Armagh this Thursday but those plans, or at least their hopes for success, have received a heavy blow as news of Donaldson's death emerged.