Police sources have said it is "very likely" that a man shot dead at a bonfire in Larne, Co Antrim on Tuesday night was killed by loyalist paramilitaries.
Mr Andy Cairns (22), is believed to have had links with the Ulster Volunteer Force but police have not yet established which organisation was involved in his killing or why he was murdered.
As many as 12 people were involved in Mr Cairns' death, which took place shortly after midnight, according to the RUC officer investigating the murder.
Det Chief Insp George Montgomery said the victim was chased and captured by a gang who "put him to the ground, severely kicked and punched him and, having done that, one of them proceeded to shoot him in the back of the head".
The RUC is investigating suggestions that a row took place in a local club before the shooting, which was carried out at an 11th night bonfire near a children's play park at the Old Glenarm Road in Larne.
Yesterday morning the scene of the shooting was cordoned off, and flowers were laid nearby. Cards accompanying the floral tributes described Mr Cairns as a "a true loyalist" and "true son of Ulster".
Mr David Ervine MLA of the Progressive Unionist Party, which has links with the UVF, said he was stunned by the killing of Mr Cairns, whom he did not know personally. There have been reports of UFF involvement in the killing but Mr Ervine said his understanding was that there was no feud between loyalist paramilitary groupings.
"Why is a 22-year-old boy lying on a slab when his first and only desire was to go and celebrate his culture?" he said.
A series of shootings in Belfast in recent months have been linked to loyalist paramilitaries. In late May, Mr Martin Taylor was killed after he and another man were attacked by gunmen in Belfast as part of what is thought to be a feud between the UVF and the LVF, with possible involvement of the UDA.
There have also been tensions between the UVF and LVF after the killing of reputed UVF commander Mr Richard Jameson near Portadown in January, and the brutal stabbing to death of two teenagers in February.
Mr Jack McKee, a local DUP councillor, was at the bonfire where Mr Cairns died, and condemned the killing.
"We have protests during the week to try and regain our culture and our identity and here we have, in our midst, Protestants shooting Protestants. People are numbed in the area that a young man could be struck down in the midst - one of their own and by one of their own," he said.
Meanwhile there were two stabbing incidents around bonfires in east Belfast on Tuesday night.