A ray of light for victims at end of very dark tunnel
In the hierarchy of victims of the conflict, informers have long ranked as the lowest of the low - not just in republican circles, but in wider society too.
Now, at last, the families of those who were abducted, stripped, shot and dumped on lonely border roads have the hope of securing a smidgen of justice for their loved ones.
Frank Mulhern's 23-year-old son Joseph was found face-down with his hands tied behind his back on a remote hillside in Castlederg in 1993.
Yesterday, Mr Mulhern described the launch of the Stakeknife investigation as "a ray of light at the end of a very dark tunnel".
The investigation led by Bedfordshire Police Chief Constable Jon Boutcher currently has the full confidence of the families. But, having been let down by so many in high places for so long, they will be keeping a watchful eye on proceedings.
The relatives' only demand is that Mr Boutcher lives up to his word of "leaving no stone unturned" in seeking the truth - that he goes where the evidence leads.
This will likely take his investigators to the very top of the security and political establishment.
Alleged head of the IRA's internal security unit Freddie Scappaticci has always denied being Stakeknife.
The activities of the agent were approved and directed by far more significant individuals than your rank-and-file Special Branch or British Army handler.
The families who lost sons, brothers, fathers and mothers see Stakeknife as a State-sponsored serial killer.
They believe the authorities allowed "£10 touts", like single mother Caroline Moreland and other poor souls, to be thrown to the wolves to protect more valuable agents.
With a team of up to 70 detectives, the investigation - named Operation Kenova - will cost around £30m. No one should begrudge a single penny of that sum.
Those in the upper echelons of the intelligence services and their political masters have stubbornly and shamefully protected "their man" and the secrets of this murky world.
Had they come clean with even a fraction of the truth years ago, no costly and time-consuming investigation would have been needed. This inquiry is the only way that the families will get answers.
Caroline Moreland was taken from west Belfast in the boot of a car to Fermanagh, where she was held for 15 days.
Her family insist that the authorities had ample opportunity to step in and save her life but chose to let her die.
She was shot three times in the back of her head as she knelt blindfolded. Her body was found on an isolated Fermanagh road in July 1994 by a woman out walking her dog.
It must not be forgotten that there are others who, just as much as the British establishment, want to keep the door closed on Stakeknife's sordid history.
In the dirty war, the hands of the Provisional IRA's top brass are filthy. Let us remember that those who claim to lead the crusade against collusion did everything possible to discredit anyone trying to expose Scappaticci as a British agent in May 2003.
Back then, he proclaimed his innocence and the Sinn Fein machine swung into action. Martin McGuinness denounced the "nameless, faceless securocrats" making outrageous allegations against an innocent man, originally from south Belfast.
Gerry Adams said he believed Scappaticci and rebuked journalists who had pursued the story.
"The losers were the media folk because, in an unquestioning way, they took a line from faceless people," he declared.
Sinn Fein leaders were on the wrong side of the truth. It is time that they, and not just the State, were held to account for their cover-up.