An INLA source told the Sunday Tribune that Brian McGlynn (28) had been using the organisation's name for drugdealing. The source said that if McGlynn's associates didn't come forward to the INLA and "disband peacefully" they would also be shot dead.

The source claimed the murder was not a breach of the INLA ceasefire because the organisation believed that applied only to members of the security forces and loyalist paramilitaries.

Despite the INLA's claim, some security and republican sources continue to suspect the Provisional IRA had a role in the murder. They said McGlynn's behaviour had upset the Provisional IRA in recent weeks.

A Police Service of Northern Ireland source said the murder was "ruthless, clinical, and had the appearances of a paramilitary hit". The source said the INLA, the Provisional IRA, and loyalists were all still suspects in the case. McGlynn had loyalist associates from his drug-dealing.

McGlynn was shot dead as he lay in bed with his girlfriend in his Fountain Hill home in the Waterside area of the city. A shot-gun was used in the attack. McGlynn has an extensive criminal record and had been imprisoned on several occasions. He was also a regular user of illegal steroids and cocaine.

The INLA said McGlynn, who was originally from the Strabane area of Co Tyrone, had been involved in criminal activity there in the 1990s. The source said he then moved to Omagh where he set up an armed drug gang which regularly used the INLA's name.

The INLA said it had broken up this gang but that McGlynn had moved to Derry and again became involved in the drugs trade, falsely using the INLA's name even though he was never a member of the paramilitary group.

Shortly before his murder, he had worked as a bouncer in several Derry pubs and clubs. He had been been employed by Estate Services Ltd, a local company which supplies security personnel.

Prominent figures in the company include Derry republicans Christopher 'Pinta' McKnight and Martin McGuinness's brother, Willie.

However, McGlynn was sacked by the company after only a few weeks. His behaviour had caused alarm among many in Derry.

McGlynn had kidnapped another local drug dealer and threatened him with a syringe which he claimed was contaminated with the Aids virus. Also, after he left Estate Services, McGlynn threatened to shoot staff in one pub.