Collusion between British security forces and loyalist terrorists in Northern Ireland was the focus of hearings on Capitol Hill this week in Washington.

The House Committee on Foreign Affairs heard testimony from Nuala O'Loan who served as the first Ombudsman (watchdog) for the Police Service of Northern Ireland.

Also testifying were Raymond McCord, Sr. and John Finucane, both of whose families lost loved ones under circumstances where there is compelling evidence of state involvement in their murders.

McCord — who has led a campaign to expose alleged police collusion between British Government agents and police informers — was the main witness in the case of his son, Raymond McCord Jr.

The 22-year-old protestant was murdered by the loyalist paramilitary UVF in 1997 near Belfast.

Speaking ahead of the hearing, McCord said it was a significant development as it is the first time a Protestant has testified on collusion.

"I've waited a long time for someone to take this case seriously." he said.

McCord testified that man who gave the orders to kill his son was loyalist UVF terrorist Mark Haddock. McCord told Congress that Haddock was "a longtime paid British Government agent, police informer and serial killer as the Police Ombudsman’s Report of 2007 established."

McCord said his son’s case was not about police corruption, but was "about police and state collusion in murder."

"A democratic society requires that the police must not be above the law. Rather, they must uphold it, and be seen to do so.  Yet my son’s case clearly demonstrates that in Northern Ireland some police officers and their agents can literally get away with murder.  This is not only collusion but also collusion sanctioned from the very top. It is not about the corruption of a few bad apples.  What does it do to Northern Ireland society when the government pays serial killers," McCord asked Congress in his testimony.

The Finucane family have been urging the British government to hold an independent inquiry into the murder of their father, Patrick, in 1989.

The 39-year-old lawyer was shot dead in front of his family when gunmen burst into his north Belfast home.

Just one of the killers was convicted, while a second was acquitted and later shot dead by former associates in the Ulster DefenSe Association.

It emerged subsequently that three top UDA men involved in the planning and execution of the murder were also working for the British intelligence services at the time.

Former Police Ombudsman Nuala O'Loan in her testimony said:

"What we did find was that Special Branch, the Intelligence arm, dominated the Royal Ulster Constabulary."

She added: "There was an absence of proper policy and controls within Special Branch and that created a vacuum within which the collusion, which I identified in my public statement, occurred."