VENGEANCE. Pure vengeance. That is the only reason why Denis Donaldson was so brutally murdered. From the moment Donaldson confessed last December that he had been a British intelligence agent for the past 20 years, Donaldson was a dead man walking. His end in a squalid remote cottage in Co Donegal was a death foretold. Indeed Donaldson must have wondered why his one-time comrades had waited so long since December to kill him.

There is no greater crime in republican eyes than to turn “tout” and betray the cause and other IRA men. The waters cleave and those who “turn” are for ever cast out. There is no possibility of forgiveness or absolution. The usual punishment was death by “nutting” — a single bullet to the back of the head — but Donaldson’s killing by shotgun in his final hold-out was more disorganised, though the end result was, grimly, the same. Because of his former leadership position close to Gerry Adams and the all-important IRA Belfast Brigade of the 1980s and 1990s, Donaldson’s betrayal was all the more profound. He was part of Mr Adams’s outer leadership circle, close to the most important republican of all and therefore spying on that same republican.

Despite Mr Adams’s denials and condemnation of the killing, there will be few Republicans shedding tears in West Belfast for the demise of yet another British informer. There is in the Republican lexicon no possibility of forgiveness or absolution. The shame of informing is akin to how the rest of society views child-sex offenders. For the informers themselves are often filled with self-loathing and hatred, frequently having been blackmailed into turning on the IRA after breaking down in police interrogation. They are human meat in an intelligence machine; used by their handlers and hated and despised by those they betray.

Nor will the shame end with Donaldson’s death. It will run like a dark river through the lives of his children and their children to come.

Although the IRA has long claimed to be a clandestine army it was always an amalgam of clans, little Irish tribes embedded along the border, in Derry or in the once grim Catholic houses estates of West Belfast. IRA men such as Donaldson grew up together, married each other’s sisters, mingled and mixed. They have no other life outside that tight embrace of family and brethren.

By admitting he was an informer, Donaldson instantly became an outcast, but there was simply no other place in the world for him to go. At the back of his mind he must have known it was only a matter of time before the IRA finished debating and sent its killers in to finish the job.

The key question is: did the IRA Army council, and therefore Mr Adams, order his death, despite their July 2005 statement that IRA volunteers cease to “carry out any activities whatsoever”. Only Donaldson’s killers know the exact answer but no one should doubt that the latent republican hatred and mendacity directed towards informers would make the decision to break such a ceasefire and kill Donaldson an easy task.

In 1999 the IRA chief of staff ordered the murder of the former IRA man Eamon Collins for having the audacity to criticise the republican leadership in print and in television interviews. Collins was doubly hated because he had confessed under police interrogation and named other IRA men before successfully retracting his own confessions. But Collins’s pleas of sorrow and calls for forgiveness fell on deaf ears. Once he had crossed the line and informed on his comrades there was no turning back.

Donaldson’s killing could, of course, — as Mr Adams’s statement seems to imply — have been carried out by a renegade republican group. At this stage it’s difficult to be certain.

But republicans are not the only people who wished for Donaldson to disappear. His death brings closure to one of the most bizarre fiascos in Northern Ireland history — the infamous “Stormontgate” police raid in 2002. In front of waiting television cameras, uniformed officers from the Police Service of Northern Ireland burst into the Sinn Fein office run by Donaldson and allegedly uncovered a top-level Sinn Fein spy ring in the Assembly — which subsequently collapsed. Donaldson himself was charged with a series of criminal offences relating to alleged spying activity. But last December all charges were dropped and in the following few days it was revealed that Donaldson had been a British intelligence agent.

In the hall of mirrors that was part of the hidden intelligence war in Northern Ireland no one has yet been able to come up with a convincing explanation both for the actions of the police and British Intelligence in the Stormont raid.

Regardless of the effect on the Assembly, the revelation that Donaldson had been a long-term agent renewed republicans’ paranoia towards the alleged legion of hidden moles within their ranks and obviously stoked up their latent fear that their entire organisation had been penetrated.

Why did Donaldson hide out in a place that is a known republican stronghold? He could, of course, have easily escaped to the great anonymities of British mainland cities. But instead he chose to wait in the last worst place on Earth for his killers to overtake him.

In the end, as both Donaldson and his one-time comrades knew, as long as he remained on the island of Ireland there could and would be only one outcome. As he waited in the Donegal cottage Donaldson could only have speculated not on the method or on the manner, but only on the “when” of his own death.

Kevin Toolis is the author of Rebel Hearts: Journeys within the IRA Soul.

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