The man who reactivated one of the weapons used in the massacre of bookmaker Sean Graham has killed himself out of guilt over repairing weapons deployed in dozens of murders, loyalist sources have claimed.

illy Bell was found with a single gunshot wound to the head at his home in Ballysillan north Belfast in October 2008.

Searches of the property uncovered 70 guns and thousands of cartridges.

A second search of a paintball center he owned in Crumlin yielded a number of reactivated weapons.

In total, more than 80 firearms and 10,000 cartridges were found by the police.

At the time, it was claimed that Bell killed himself because he had terminal cancer, but sources said he could no longer live with the guilt of knowing that the weapons he had reactivated had been used in dozens of murders and attempted murders, including the four men and the 15-year-old boy shot dead in the attack on the Ormeau Road bookmakers in 1992.

On Tuesday the Police Ombudsman published the findings of an investigation into a series of murders by the South Belfast UDA, which found evidence of ‘collusive behaviour’ by the RUC special branch .

The Browning 9mm pistol used by one of the loyalist gunmen in the attack on Sean Graham had been returned to UDA police informant William Stobie by his RUC handler.

The police ombudsman did not name Stobie, referring to him as Person I, in his report on the atrocity.

Stobie was assassinated by the UDA in December 2001.

The Browning pistol was also used in the murder of Aidan Wallace (22) at the Devenish Arms bar on Finaghy Road North in December 1991. An eight-year-old child was shot in the head and lost an eye when same attack.

A gun used in the murder of 22-year-old Martin Moran was also reactivated by Bell. Mr Moran was shot dead in October 1993 while delivering a Chinese takeout meal. He had taken the job to earn money after his partner had given birth to their first child five weeks earlier.

The ombudsman said the Webley revolver used in the murder had been rendered inoperable, but “under circumstances which cannot be established” it had been reactivated. The weapon was later recovered from a house on the Rathcoole estate.

One of the firearms used to kill mother-of-two Theresa Clinton in 1994 was also believed to have been reactivated by Bell.

The 9mm Sterling submachine gun, which had no history, had been certified unserviceable.

The ombudsman was unable to establish how it was reactivated and in the possession of the UDA, but loyalist sources said Bell repaired it and dozens of similar weapons for the UDA and UVF.

The weapon was recovered by police the day after Mrs Clinton’s murder, during a search in the Annadale Embankment area of ​​south Belfast.

Another weapon used in the south Belfast woman’s murder was an RUC personal protection weapon which had been reported stolen.

In her report, mediator Marie Anderson found that deactivating weapons and returning them to paramilitaries was common practice.

“Cover ops, involving the deactivation of weapons with the aim of thwarting major crimes, can be an effective policing strategy if accompanied by appropriate control mechanisms,” she said.

“However, the policing activities relevant to this investigation carried significant risks.

“I am of the opinion that most important was Person I’s unreliability, questionable motives and known technical knowledge of weapons within the UDA/UFF.

“I am also of the opinion that the police planning and contingencies that went along with this operation were lacking.”

While Bell was linked to the UVF, at the time of his death the terrorist gang denied having anything to do with his arsenal of weapons and ammunition.

According to sources, he had been reactivating weapons for the UDA and UVF for decades.

Bell, who killed himself with an illegally owned gun, was an expert described by those who knew him as a ‘gun fanatic’ who could convert deactivated guns intended for use as collectibles into working firearms .

His skills were sought after in the 1980s and 1990s, with reactivated weapons used in dozens of murders.

Sources said that during the UDA and UVF decommissioning process, dozens of weapons that had been reactivated by Bell were handed over to General John de Chastelain’s team.

The UVF was decommissioned in 2009, the year after he committed suicide.

After the loyalist ceasefires of 1994, Bell continued to reactivate weapons that had been certified unusable, reselling them to criminals for a huge profit.

He also bought and sold old military vehicles, storing them at his paintball center in Crumlin.