'Will it pass the Proctor test? It can only work if it satisfies people like his widow," a colleague recently asked me over lunch.
We were discussing the possibility of immunity from prosecution in return for information on Troubles violence being offered as part of the package emerging from the Haass talks.
He was referring to the case of John Proctor, an RUC reservist shot dead by the IRA in 1983. The 25-year-old was gunned down in a hospital car-park after visiting his wife, June, and their second child, a newborn baby now also named John.
Like most RUC murders – indeed, like most Troubles murders – it was unsolved. There were suspects, but no evidence to bring them to court.
Unsolved, that is, until the Historical Enquiries Team (HET) reviewed the case and found, tucked away in the evidence from the crime scene, a cigarette butt that had been properly preserved in an evidence bag.
DNA tests linked it to one of the initial suspects, a local man called Seamus Kearney, whom June McMullan, John Proctor's widow, said she had frequently passed in the street.
Under the terms of the Good Friday Agreement, Kearney's sentence was reduced to two years for murder and he may be out within one. After the trial, Ms McMullan took the opportunity to condemn proposals by John Larkin, the Attorney General, for a halt to all prosecutions on Troubles-related violence prior to the signing of the Good Friday Agreement in 1998.
She was pleased, even in view of the light sentence. "Everyone deserves their day in court. After 32 years, it was good to hear the judge say he was guilty. I am relieved it is all over," she stated.
She added: "Surely it is better for people like Kearney to come forward and confess what they did? Serving two years in jail and getting it over with is better than looking over your shoulder for 32 years like Kearney has been doing, wondering when there will be a knock on the door."
This is a rare case; in the Troubles era, evidence was generally not preserved securely enough to be DNA-tested and used in court.
The HET was set up partly to check if anything had been missed and pass on evidence for prosecution, where possible.
What happens, though, after the HET has reviewed a case and found nothing worth using in court? In those cases, it used to pass on its reports to the families with its best guess of what had happened and tried to answer any questions they had.
Unfortunately, the HET is currently doing none of this, while its terms of reference and procedures are redrawn following a critical review by Her Majesty's Inspectorate of Constabulary.
One of the big tasks of the Haass talks must be to get the HET back on-track – without this kind of systematic review by independent police investigators, any evidence lying in bags somewhere in RUC records is likely to remain undiscovered and will do little but gather dust.
When the HET has completed its review, the case becomes stronger for offering immunity in return for further information, particularly if the families of victims want it, but also in the interests of the historical record; of "finding out what really happened", as Dr Haass put it.
If a thorough reinvestigation found no grounds to prosecute, then the release of documents, accompanied by targeted offers of immunity to fill in gaps in the evidence, might be something widows and survivors could accept as the next step towards the truth.