Milltown massacre gunman Michael Stone has told the Police Ombudsman that the weapon used in the attack was given to him by an RUC officer who was also in the UDA.
However the loyalist - who is serving a 30-year jail sentence for a sectarian murder campaign - insists his rogue cop contact had no idea what the police-issue Ruger revolver was to be used for.
The gun ended up being seized by republicans who chased after Stone following the cemetery slaughter.
The UDA killer also claims that IRA veteran Seanna Walsh, who was among this group, tried to shoot him in the head with the weapon but it jammed. Mr Walsh, now a Sinn Fein councillor in Belfast, refused to respond to Sunday Life inquiries about the allegation.
This newspaper further understands that the RUC officer who Stone says provided him with the Ruger took his own life in 1989, the year after the Milltown attack that claimed three lives. His name has been passed to the Police Ombudsman.
When asked if its investigators met and took statements from Stone, a spokesman for Marie Anderson's office said: "We often speak to a range of people when following lines of inquiry in our investigations.
"These discussions are confidential and we would not wish to identify in public anyone who has provided us with information."
Stone has previously admitted that an RUC officer drove him to collect the weapons used in the 1988 Milltown attack.
However, this is the first time he has confessed to having been handed the guns and ammo directly by a serving cop who was also in the UDA.
A close confidant of the 64-year-old loyalist told Sunday Life: "Michael was interviewed by the Police Ombudsman some three years ago regarding the Ruger. He told its officers it had been swapped with the quartermaster of a paramilitary organisation in Mid-Ulster some time prior to Milltown.
"The quartermaster had dual membership of both the RUC and a paramilitary organisation (UDA), which was not illegal at the time. The man had no knowledge of Stone's intention for the weapon, it was not discussed."
Stone, via his friend, claims the officer whose name is known to the Police Ombudsman, died in a suspicious suicide the following year.
The pal added: "The story was that false allegations regarding money and firearm certificates had been made against him.
"This co-operation, not collusion, between police and loyalist paramilitaries was down to them having a common enemy."
Stone, who suffers from Motor Neurone disease and can barely walk, also made several other startling jailhouse revelations about the Millown massacre and his terror past.
Sinn Fein refused to respond to Stone's claims that Cllr Walsh tried to execute the UDA gunman with his own weapon. The veteran republican admits to being among the mourners who gave chase to the loyalist after he had thrown hand-grenades and opened fire at the IRA Gibraltar Three's funerals.
As of last night Walsh, who served more than 21 years in jail and read the Provo's 2005 decommission statement, was neither confirming or denying that he tried to shoot Stone.
The Sinn Fein politician was caged in the Maze Prison on three occasions, firstly after being arrested in 1973 for robbing a bank and again in 1976 for possession of a firearm. From the Short Strand district of east Belfast, Walsh went on to become Officer Commanding (OC) of the IRA prisoners in the jail. He was arrested again in the 1980s after being caught making explosives and was released in 1999 under the terms of the Good Friday Agreement.
Recalling the moment Stone was apprehended by Milltown mourners after attacking the funerals of IRA members Mairead Farrell, Sean Savage and Dan McCann, the loyalist's friend said: "Some of those giving chase were plain-clothed IRA volunteers. One of these men was Seanna Walsh who received shrapnel wounds.
"What Walsh doesn't brag about is that he was the last person on the day in possession of the Ruger 357 owned by Stone. He chased Stone and when he thought he was out of ammo shouted 'kill the Orange bastard'."
Stone's pal said the loyalist used a back-up Ruger to fire two shots at Walsh, who was not known to him, which missed and the republican responded by playing dead.
He added: "Minutes later when Stone reached the motorway and discarded the guns, one of which was jammed with bog debris, a voice was heard shouting, 'stand back, stand back'.
"It was Walsh, and he stepped forward and attempted to fire the Ruger into Stone's temple. He tried six times to no avail and placed the weapon in the waistband of his trousers."
Stone was then bundled into a car hijacked by the IRA on the M1 motorway, but was rescued by RUC officers who sped to the scene. The UDA killer claims at this point, Walsh shouted "say it's a citizen's arrest".
Two years ago the republican talked publicly about the injuries he received in the Milltown Massacre, saying a hand-grenade thrown near him by Stone "sizzled".
Walsh explained: "I felt an impact on my inner thigh and I realised that I was injured. They actually put me into the hearse, they gave me anaesthetic and operated, took the shrapnel out and gave me a lot of stitches."
After being taken into custody by police, Stone admitted carrying out six sectarian killings for which he was jailed for a minimum of 30 years.
He was freed under the terms of the Good Friday Agreement in 2000 but returned to jail in 2006 for trying to murder Gerry Adams and Martin McGuinness at Stormont. Despite being seriously ill, the loyalist is not eligible for release until at least 2024.
Stone's Milltown victims were Thomas McErlane, John Murray and Kevin Brady, each of whom were attending the funerals of three IRA members executed by the SAS at Gibraltar.
The cemetery massacre was captured by a multitude of TV cameras making him infamous across the world. Prior to Milltown, the UDA hitman murdered innocent Catholics Patrick Brady, Kevin McPolin and Dermot Hackett.