The death of a loyalist killer has left many unanswered questions over the persistent allegations of security force collusion in murder, a prominent human rights group has said.
Progressive Unionist Party (PUP) member William McCaughey died at his Lurgan home on Wednesday following a long illness.
He was the PUP's representative in north Antrim and had played a key role in the loyalist pickets outside a Catholic Church in Harryville, Ballymena.
McCaughey and his former colleague, ex-RUC sergeant John Weir, both members of the force's Special Patrol group, were convicted of involvement in the 1977 sectarian murder of William Strathearn in Ahoghill.
Mr Strathearn, a father-of-seven who was well-known in GAA circles, was lured to his death in what became known as the Good Samaritan killing.
A UVF gang called to his door claiming a child was sick and urgently needed attention.
McCaughey, a long serving member of the RUC at the time of the killing, was also convicted for his part in the 1976 bombing of the Rock bar in Keady, where he shot at a customer fleeing the scene.
Two other RUC officers were handed suspended sentences for their part in the bombing.
The guns used in the attack were the same ones used in the murder of Co Armagh brothers Anthony, John and Brian Reavey in Armagh in 1976.
He was also implicated in the killings of three members of the O'Dowd family Barry, his brother Declan and their uncle Joe targeted 10 minutes after the Reaveys.
However, he never faced any charges in connection with the O'Dowd murders.
Both families suspect the security forces were involved in the killings.
McCaughey was jailed for kidnapping of a Catholic priest in Ahoghill, Co Antrim in 1978.
He refused to cooperate with Mr Justice Barron's probe into the 1974 Dublin and Monaghan bombings.
However, the inquiry found that claims of collusion from his former RUC colleague John Weir "must be treated with the utmost seriousness".
Mr Weir has alleged that members of the RUC and UDR colluded with paramilitaries in the killings.
However, McCaughey insisted in 2003: "What Weir said was 95 per cent fiction".
Last night (Friday) human rights group the Pat Finucane Centre (PFC) said he may have taken vital secrets in relation to security force involvement in murder, to his grave.
"We would sense there are going to be people who were members of the RUC and UDR in the murder triangle of the 1970s who are glad he has passed away," said a PFC spokesman.
"There were many unanswered questions not only about his activities but about collusion."
Although McCaughey played a key part in the loyalist protest at Harryville Catholic church, he was later involved in removing graffiti from the church.
Ballymena SDLP councillor Declan O'Loan said yesterday: "There is no doubt that Billy McCaughey was responsible for some terrible things in the past.
"Some of his local contributions were disruptive and unhelpful, even up to quite recent times.
"But I have talked to him at length and I have no doubt that much of his thinking was forward looking and progressive.
"He was way ahead of most unionist politicians in this area. I have no doubt that if he had been entirely consistent he could have been a more influential figure.
"But he started significant movement within loyalism and that deserves to be recognised. He also faced up to his final illness in a way that was very courageous and uncomplaining."
The PUP said McCaughey "will be greatly missed both for his work in conflict transformation and as a friend and colleague".
"The party executive would ask that the family's wishes for privacy be respected at this difficult time."