The Northern Secretary has expressed confidence in the officers investigating the killing of the solicitor Ms Rosemary Nelson and pledged that all allegations of collusion will be examined.
Speaking at Lurgan RUC station yesterday, where he was briefed by the head of the investigation, Mr Colin Port, Deputy Chief Constable of the Norfolk Constabulary, Mr Peter Mandelson said he felt reassured that it was the most thorough investigation of its kind.
Next Wednesday marks the first anniversary of the killing of Ms Nelson, who died when a booby trap under her car exploded as she drove from her home in Lurgan, Co Armagh. Allegations of security-force collusion surround the incident.
The police investigation team from Britain and RUC officers had interviewed 5,000 people, "leaving no stone unturned", Mr Mandelson said. The killing was a despicable crime, and he was confident the team would uncover any possible lead due to the large scale and detailed nature of the inquiry.
He could not confirm if a breakthrough was imminent in the case but he called on anyone with helpful information to come forward.
"If there is any evidence of collusion that will be properly pursued with the utmost seriousness and complete integrity by the investigating team," he said.
"I give my full backing to Colin Port and all those who are involved in this investigation to pursue their investigation and every inquiry they need to take up for as long as they need to, with all the resources that they need, for however long it takes," Mr Mandelson added.
Commenting on continuing demands from friends and family of Ms Nelson for an independent public inquiry into her killing, Mr Mandelson said this could not be ruled out but it was not under consideration. "I'm not going to do anything at this stage that is going to jeopardise criminal proceedings," he said.
A Sinn Fein delegation later met Mr Mandelson at Stormont to discuss the investigation. Dr Dara O'Hagan said the delegation had a "frank discussion" but party members were not happy with some of the Northern Secretary's responses.
"We asked him, a year on, how far the investigation has really progressed, and he never answered us," said Dr O'Hagan. She feared the collusion issue was "diversionary rather than integral" to the investigation.
The delegation outlined the alleged death threats made to Ms Nelson by RUC officers. "We still have serious concerns that RUC officers are involved in the investigating team and that the inquiry is still partially based in Lurgan RUC station.
"But the one positive aspect from the meeting was that the possibility of an independent inquiry has not been ruled out by Mr Mandelson," Dr O'Hagan said.