A witness has been accused of "sexing up" claims that undercover Sunderland soldier Robert Nairac was present at a notorious Irish massacre.
Captain Nairac, who grew up in Thornhill Gardens, Ashbrooke, was murdered by the IRA in May 1977 with investigations still ongoing to find his missing body.
At the same, however, a separate inquiry is debating claims that he actually worked undercover with the terrorist group and was present at the execution of 10 Protestant workmen in
South Armagh, Northern Ireland, in 1976 by an unknown gang.
Gerald Byrne, one of the first people at the scene, was quizzed at the resumed inquest into the killings over a statement he gave to the authorities in 2013 stating that Captain Nairac was
the man who stopped the minibus carrying the victims.
Ministry of Defence (MoD) barrister Peter Coll told him at Belfast Coroner's Court: "You are sexing this up.
"You are creating a seam of disinformation which pushes the focus away from IRA involvement to British military involvement in this terrible atrocity."
Mr Byrne, a construction company owner who is in a relationship with a woman who used to be married to a member of the security services, denied this.
He said: "I am merely relating what I have been told. There is no desire to create disinformation."
Mr Byrne added that he still lies in bed reliving the memory of the atrocity and can remember seeing the bullet holes after gunmen opened fire on a remote road.
He told the inquest: "The smell of the scene was indescribable. It was the smell of death. The blood was running down the road."
Colleagues of Captain Nairac used the recent 40th anniversary of his death to distance him from any involvement in the Kingsmill massacre and other atrocities committed during Ulster's bloody Troubles.
While the intelligence officer's exact role in the late 1970s is still a mystery, one of the theories behind his kidnap from a Republican-supporting pub inside the Northern Irish border is that
his cover was blown after infiltrating the IRA.
It is accepted that he was tortured and executed in the Republic of Ireland the following morning with his body believed to be buried nearby in dense Ravensdale Forest.