A report on the UVF murder of Raymond McCord junior will confirm collusion was a reality during the Troubles, SDLP leader Mark Durkan has predicted.
Mark Durkan says report will show collusion was not a myth
Mr Durkan said the report, by Police Ombudsman Nuala O'Loan, will be extremely serious and show collusion was not a "nationalist myth".
The report is expected to be published at the start of next week.
The Foyle MP was being interviewed for Saturday's Inside Politics programme on BBC Radio Ulster.
Raymond McCord Junior, 22, a former RAF man, was beaten to death and his body dumped in a quarry in 1997.
There have been allegations that a leading member of the UVF gang responsible for his murder and several other killings in the north Belfast/Newtownabbey area were police informers.
"I think the report will show that we had an RUC informer who was allowed to murder again and again and again - Catholics, Protestants, paramilitaries, civilians, even a minister of religion," Mr Durkan said.
"It absolutely stinks. But we also have to ask why are we only getting to this now.
"We are only getting to this now because some us insisted on the police ombudsman having the powers to investigate these things and investigate the past."