The Historical Enquiries Team (HET) has said that a former soldier lied about the fatal shooting of a woman in Londonderry in 1975.
A HET report released to the family of 22-year-old Bernadette Friel said that a claim that she was shot during a game of "Russian Roulette" was fabricated.
The HET said Thomas Ramsay deliberately shot her and then told investigators a series of lies about what happened.
Ramsay's version of events was accepted and he spent eight months in jail.
Ms Friel, who had a four-year-old son, died from a single wound to the head, two days after she was shot in the bedroom of Ramsay's home in the Carnhill area of Derry.
He had been charged with murder, but the charge was reduced to manslaughter, after the Director of Public Prosecutions accepted his version of events.
His "Russian Roulette" story was the officially accepted version of events for 34 years, until the publication of the HET report at 1100 BST on Monday.
The report said that Ms Friel was a friend of Ramsay's wife and occasionally stayed at the house.
Ramsay's 16-year-old brother-in-law Hugh Stanley was also staying there on the weekend of the shooting.
On Sunday 19 October 1975, Ramsay and Stanley followed Ms Friel when she went upstairs into a bedroom.
Almost immediately a shot was heard and Ms Friel sustained a single gun shot wound to the head.
During a subsequent search of the house, firearms were discovered.
Stanley was given a two-year conditional discharge for firearms offences, but no action was taken over the manslaughter offence, on the direction of the DPP.
Following the publication of the HET report, Ms Friel's family said in a statement the "Russian roulette" story had greatly added to their distress.
They said that the pathologist's findings proved that the position of the wound and the direction of travel of the bullet "completely excluded any possibility that Bernadette could have shot herself".
They said that the case had raised "serious questions" about the impartiality of the Director of Public Prosecution who "recommended no charge against Stanley, despite the RUC's recommendation that both be charged with murder".
The Friel family's statement added that they had been left with unanswered questions.
"It seems very suspicious that he received such a light sentence while at that time it was common for anyone caught with this amount of arms to have received a much heavier sentence.
"It is also very strange that Ramsay was allowed go in the ambulance with Bernadette and was taken from Altnagelvin Hospital to Fort George where he remained for several hours before he was handed over to the RUC.
"Although Bernadette hasn't got justice, we know the HET has gone as far as they can with this report.
"The family would like to thank the soldier who comforted Bernadette at the scene. We will be writing to him through the HET."