Gerard Slane and Terence Mc Daid

Part of the story of Nelson's double life was revealed when he was tried in 1992 on a range of charges including five of conspiracy to murder. He was initially charged in connection with the murders of Catholic men Terence McDaid and Gerard Slane, shot in separate loyalist attacks in 1988. These charges were eventually dropped. Press reports at the time claimed Nelson had struck a deal to plead guilty to 20 offences in return for the withdrawal of the two murder allegations.

Had he been convicted of the murders he would have faced mandatory life imprisonment, but instead was eventually sentenced to ten years. At Nelson's trial the court was told he had played a "vital and indispensable role" in the murders of Mr McDaid and Mr Slane. Given his guilty pleas to a series of other charges the Crown decided not to proceed with the charges that Nelson aided and abetted the two killings. At the trial the Crown's prosecuting lawyer, Mr Brian Kerr QC, told the judge Lord Justice Kelly said:

"The decision has been reached after a scrupulous assessment of the possible evidential difficulties and a rigorous examination of the interests of justice."

He said Nelson had told his army handler on five occasions that Terence McDaid's brother, who often visited him, had been targeted by the UDA before the killing. It was argued that Nelson had therefore no "intention that any harm should befall Terence McDaid." Gerard Slane was shot in front of his wife after gunmen smashed their way into his Waterville Street home in west Belfast on September 22, 1988.

Mr Kerr said Nelson had told his army handlers the UDA was targeting Mr Slane (26) ten days before the murder. The men's widows have demanded the full story behind their husbands' murders amid continuing claims over the security force role in the episodes. They have made their calls alongside a third bereaved woman - Geraldine Finucane, whose husband Pat was gunned down by loyalists in February 1989.

The role of Brian Nelson, British military intelligence and that of the RUC in the loyalist murder of solicitor Pat Finucane has also commanded international attention over the last ten years. Brian Nelson, a former member of the Black Watch Regiment, was arrested during Metropolitan Police Commissioner John Stevens' inquiry into collusion between security forces and loyalist paramilitaries.

He is believed to have been recruited into the UDA in 1972. He operated as a British army spy in the early 1980s but was recruited back into the army in 1987. His handlers however, brought him back from Germany and asked him to again infiltrate loyalist paramilitaries. He then gathered a considerable amount of intelligence on republican suspects. When asked by the UDA for a target, Nelson would consult his index system, select a target, check the victim's movements and then inform the assassins. He was also linked to a huge loyalist arms cargo imported from South Africa in 1985. Despite the fact that he was feeding back information to intelligence bosses, security forces failed to capture a substantial portion of the consignment.

Brian Nelson was found guilty on 11 counts of possession of documents, three of collecting information, one of possession of firearms with intent and five counts of conspiracy to murder. Sentenced to ten years imprisonment, he was permitted to serve the bulk of his sentence in England. He was released in August 1996.