Speaking out for the first time, the Catholic father of a man killed by the IRA and the Protestant sister of a woman battered to death by the UDA have the same message. They both want justice.
"We were more like mates than father and son, you know," west Belfast man Frank Mulhern says of his son Joe, recalling how he went to Wicklow for a break to deal with depression 20 years ago.
The 23-year-old's body was found near the Tyrone border at Castlederg. He'd been interrogated by the IRA, accused of passing information to Special Branch, then shot dead.
He was away for ten days. The next time I saw him, he was in the morgue in Altnagelvin Hospital.
Frank Mulhern, victim's father
Six weeks later, Joe's father found himself face-to-face with the head of IRA security Freddie Scappaticci - himself a double-agent codenamed Stakeknife.
"I asked him how my son had died and he said that the guy that shot him ... the first shot hit him in the neck and he shouted at him to shoot him again. And the second shot hit him in the back of the head and apparently that was what killed him," Frank reveals.
The inquest a year after Joe's murder found he had indeed been shot twice.
To Frank, that means Scappaticci was present at his son's interrogation by the IRA and that he had to have been present at the execution to know the details of the killing.
More than 40 people were executed by the IRA's internal security unit for doing what Scappaticci was doing - getting paid by the State for giving up IRA secrets.
Last year, the Historical Enquiries Team had Scappaticci arrested and questioned about Joe Mulhern's murder. He was released without charge.
Margaret Thatcher said: 'Murder is a crime; maiming is a crime; crime is crime is crime.' Except, apparently, when it comes to the Government's own security services.
Chris Moore, UTV Insight
Meanwhile, in a loyalist drinking den in north Belfast in March 1987, a 23-year-old woman and mother-of-two was unaware of the fate that lay ahead.
Lorraine McCausland was to be battered to death, with the main suspect in her killing a leading member of the UDA.
"There wasn't part of her body that wasn't marked, they had beaten her that badly," her sister Cathy McIlvenny tells Insight, adding that her family has since lost faith in the justice system.
An investigation by the Historical Enquiries Team in 2009 couldn't confirm collusion, but they did tell the family that, while the main suspect was not an informer in March 1987, he was by April 1987.
"I think high-ranking officers in Special Branch played games with people's lives," Cathy says.
They killed knowing they were never going to be brought to court for it.
Cathy McIlvenny, victim's sister
Insight's Chris Moore says that growing numbers of bereaved families are demanding the truth, in the aftermath of the Sir Desmond de Silva report that confirmed the State had colluded with armed terrorists in the murder of Belfast solicitor Pat Finucane in 1989.
Belfast solicitor Kevin Winters, who represents more than 30 families seeking accountability from the State on collusion issues, describes the de Silva report as: "one of the most startling pieces of work to come out of the conflict".
Insight looks at the roles of four State paid agents: Brian Nelson known as British Army agent 6137, whom de Silva said played an active role in UFF murders; Ken Barrett, or Special Branch Agent Wesley who boasted to police that he murdered Pat Finucane; Mark Haddock or 'Roxy' who got a Special Branch pay rise after his first murder; and agent Freddie Scappaticci - Stakeknife.
Insight: Live and Let Die is available on the UTV Player for 30 days.