A notorious Belfast political assassination which allegedly involved MI5, army intelligence and Special Branch officers is the subject of continuing negotiations between the authorities and the family of the victim.
Those involved in the killing of defence lawyer Pat Finucane, who was shot 14 times by loyalist gunmen in 1989, have already been shown in court cases and official reports to have included agents of the security forces.
Mr Finucane angered many, at various levels of the security forces, by his effectiveness in defending clients who were members of the IRA and other groups at the height of the Troubles.
The central allegation is that the loyalists who shot him were encouraged or ordered to do so by security force "handlers". The suspicions have deepened as more details have emerged over the years.
The Government has yet to announce if it will set up a public inquiry into the killing but authorities announced yesterday that officials had held "constructive" meetings with representatives of the Finucane family.
The Northern Ireland Secretary, Owen Paterson, said he had decided, with the agreement of the family, to take two months before reaching a decision.
Peter Madden, the family solicitor and Mr Finucane's one-time partner, said yesterday: "Although these were constructive and useful meetings, the fact remains that the independence of a tribunal is fundamental – the essence of a proper inquiry is independence."
The family has for years been at odds with the authorities over the form of an inquiry, with widow Geraldine Finucane and her relatives insisting on maximum disclosure in public proceedings.
The Labour government agreed to hold an inquiry, but in the meantime introduced legislation which has greatly limited the scope of such hearings, and given ministers a role in them. The compelling reason for this was said to be to prevent a recurrence of the costly and time-consuming Bloody Sunday inquiry.
Human rights activists claim, however, that another motive was to limit further revelations in the Finucane case.
Few doubt that any such inquiry would unearth troubling secrets of huge embarrassment to the authorities. Over the years, senior ministers and officials have privately conceded that intelligence agencies were deeply involved in the episode. One high-ranking official said that, of all the many security controversies, "This is the smelliest of them all."
A month before Mr Finucane's shooting, a Conservative minister had declared he believed there were "a number of solicitors who are unduly sympathetic to the cause of the IRA".
Later it emerged that Brian Nelson, a senior "intelligence officer" within the illegal Ulster Defence Association (UDA), had been planted there by the army. Although he was not charged with the killing, he claimed he had informed his army handlers that one of the leaders of the UDA's assassination teams had asked him to gather information on Finucane.
It later emerged that another UDA member, William Stobie, had supplied the assassination squad with their weapons and was a Special Branch agent. Charged with the Finucane murder, he declared in court: "I was a police informer for Special Branch and on the night of the death of Pat Finucane I informed Special Branch on two occasions that a person was to be shot."
In another twist, the UDA member Ken Barrett was given a life sentence for the murder after BBC Panorama secretly filmed him boasting of his role. He claimed he had been encouraged to kill the solicitor by a senior police officer.
The former CID detective-superintendent who headed the murder investigation later said Special Branch had not told him one of its agents had been involved. If they had, he said, he was "pretty certain we could have brought the investigation to a successful conclusion".