The great uncle of golfing star Rory McIlroy was killed in a sectarian attack carried out by a loyalist murder squad who were described by police as "sadistic fiends".
Joseph McIlroy was just 32 when he was shot dead in the Orangefield area of east Belfast on November 21, 1972.
While it was originally thought the father-of-four was killed by the UVF, recently uncovered secret intelligence files reveal those responsible belonged to notorious UDA unit known as the Baker/McCreery Gang.
The first loyalist supergrass, Albert 'Ginger' Baker was a member of the infamous UDA 'G4 unit' which carried out a series of brutal murders in Belfast in the early 1970s.
The 'G4' reference is believed to relate to the UDAs 'G Company', Number 4 platoon, which operated in the Lower Newtownards Road area of east Belfast.
The gang was also known as The Young Newtons.
A former British soldier, Baker later received a life sentence for killing four men and claimed to have links to British military intelligence.
The gang is thought to have been responsible for killing 22 people, including up to eight in 'romper-room' murders.
These involved the kidnap, torture and savage murder of innocent Catholics, usually in loyalist drinking dens.
The loyalist unit was led by UDA founding member Ned McCreery, who was gunned down by his own organisation in 1992.
Police said Mr McIlroy, who was repairing a washing machine in the kitchen of his home at the time, was not involved in any political organisation and was killed simply because he was a Catholic.
The innocent victim was a brother of Rory McIlroy's grandfather Jimmy.
McIlroy, who is originally from Holywood in Co Down, is one of the world's best-known sportsmen and has won world wide golf tournaments, including four major titles, during his glittering career.
While it was known that his great uncle had been killed by loyalists, fresh details have now emerged.
A British military intelligence file recovered by Ciarán MacAirt, of the research charity Paper Trail, reveals for the first time that it is believed Mr McIlroy was killed by the UDA.
The document, which is marked secret, is headed "The Young Newtons - G4 (Company) UDA, East Belfast" and relates to intelligence received the night Joseph McIlroy was murdered.
The information is graded A2 and appears to identify the killer, although this information is redacted.
Another section of the document is completely redacted while a comment section is partly hidden and makes reference to The Young Newtons.
The vicious gang has been linked to other savage murders around the same period, including that of Catholic man Patrick Benstead (32).
Killed on December 2, 1972 and originally from Short Strand, Mr Benstead was last seen leaving a pub on the Falls Road the evening before his naked body was found in an alleyway in the loyalist Crossley Street area of east Belfast.
A victim of a so-called 'romper room' attack, his murder shocked even the most hardened observers.
At the time, police described his death as a "grisly, revolting murder" carried out by "sadistic fiends".
Shot twice in the head, a cross had been burned into his back alongside the letters 'IRA' and the number '4'.
The number '4' is believed to be a reference to the 'G4' unit.
On the same night more than 50 years ago, a 26-year-old Protestant woman, Sandra Meli, was gunned down by the UDA at her home at Flora Street in east Belfast.
The mother-of-one was married to a Catholic and police believed he was the target.
Another intelligence document, again marked 'secret' and dated December 4, 1972, reveals that on the night he was killed the murder of Mr Benstead was discussed at a meeting held in what was described as 'UDA HQ'.
"The following members, who were all under the influence of drink boasted how they tortured Benstead before shooting him," the document states.
The names of those alleged to be present were redacted.
Incredibly, the intelligence document also reveals how rival UDA units in east Belfast were jealous of each other's murderous exploits.
"The Young Newtons, (who have boasted the killing of four RCs) and units from Dee Street and Sydenham have been responsible for the spate of murders in east Belfast.
"The Sydenham unit is jealous of the success in these killings by the Young Newtons.
"The Sydenham unit and Dee Street units work closely together."
The Young Newtons' HQ was also identified in the document.
The file also refers to the wider activities of The Young Newtons in east Belfast on the night Mr Benstead and Ms Meli were killed.
The redacted document names two people it is claimed were responsible for the murder of Mr Benstead.
Other victims of the G4 gang included James Patrick McCartan (21), who was kidnapped from an east Belfast hotel in October 1972.
He was later brought to a 'romper room' where he endured a terrifying ordeal before he too was murdered.
Reports from the time reveal that British military intelligence had forged ties with some members of the UDA in east Belfast.
At the trial linked to the murder it emerged that on hearing of the abduction of Mr McCartan, a British army intelligence officer went to Sydenham UDA club and spoke to two men.
The pair, who later stood trial along with several others, said they would see if there was anything they could do.
In 1973 Albert 'Ginger' Baker was convicted of the murder of Mr McCartan and three other Catholic men, Philip Faye (21), Paul McCartan (52) (no relation), and Patrick Heenan (50).
Other documents uncovered by Mr MacAirt reveal that classified RUC documents had fallen into the hands of prominent UDA member Davy Payne and were subsequently produced at a high-level UDA meeting in October 1972.
A former British soldier, Payne has been described by author Ian Wood, who wrote a book about the UDA, as a "sadist addicted to the use of knives to torture and mutilate those they abducted, including women, before killing them".
A document reveals that at a meeting of the UDAs 'Central Council' Payne produced photos of IRA men, "police files" and "an up-to-date wanted list".
The information was contained in a folder marked "classified information".
The documents also reveal that a cash bounty had been placed on the heads of IRA men, whose redacted details appear to have been included.
"The following have been selected for assassination by the UDA as they are thought to be IRA.
"There is a bounty of £100 for each one."
Payne, who died in 2003, was arrested in 1988 while trying to transport part of a haul of weapons smuggled in to the north with the help of British military intelligence.
Mr McAirt said that in the early 70s Payne had worked closely with former military agent and fellow UDA man Brian Nelson.
A British army agent, in the 1980s he provided information to UDA murder gangs that resulted in the murder of dozens of Catholics.
Nelson has also been linked to the smuggled cache of weapons brought into the north in 1988.
Mr MacAirt said the secret files prove that British military intelligence had a high-level and trusted agent operating within a gang of serial killers who were guilty of some of the most brutal murders of the conflict.
"If that agent is not the British soldier Albert Baker as he alleged, who is it?" he asked.
"There is at least one other."
Mr MacAirt said the "horrific murders" were carried out "at a time when the UDA was a legal organisation and only Irish Catholics were being interned and incarcerated without charge".
"Would Britain allow the UDA to flourish in Birmingham or Bristol rather than Belfast?" he asked.
Kevin Winters, of KRW Law, said: "The latest revelations from Paper Trail are an important addition" to evidence it had in its pending High Court actions against the state for liability in the cases of Benstead, McCartan and other linked cases.