Secret diaries of agent - and questions over fresh claims
Denis Donaldson spent the last few weeks of his life detailing his role inside the IRA and his work for the British.
He would spend hours writing into a journal about Provo operations he compromised; and, it seems, others he didn't pass on to his handlers.
When his killers fled after the murder, they didn't realise Donaldson's diaries - containing a myriad of British state and IRA secrets - were just a few feet away inside the living room of the cottage.
But he wasn't writing a 'tell-all' book. Gardaí believe Donaldson regretted his role as an agent and was recording his memoirs for the Republican Movement.
Gardaí have said it contains enough detail to put lives at risk - and have refused requests from his family to see it.
It is understood that the decision to kill Donaldson was taken by a leading dissident in Derry within days of his location outside Glenties being revealed in March 2016.
But the idea that those dissidents were being directed or commissioned to carry out the murder by the Provisional IRA has been dismissed by the Real IRA, the latter ridiculing the former for not killing Donaldson first. Security sources say neither the PSNI nor the Gardaí have ever investigated any link to Gerry Adams.
One former British intelligence officer said that the British side had more to lose with Donaldson alive.
They believed he may have become a double agent - and was back working for the republican side; preparing his journals for them.
The source said: "I don't believe Adams had to give anyone the nod for this attack because, if part of the BBC theory is to be believed - that the south Armagh IRA wanted him dead - Adams would not have been the person to ask.
"The BBC claim doesn't stack up and I'd question the role claimed by their source," said the former undercover intelligence officer. "If dissidents were being pushed to carry out the attack by the Provos I can't see them doing business with the individuals concerned as they are sworn enemies.
"If anyone other than the dissidents were behind this, then you'd have to look at the British side and their links to those who ordered the killing inside the Real IRA. You have to weigh up who had most to lose keeping Donaldson alive - and you would have to say that was the British."