Up to 50 murders allegedly linked to a British spy in IRA 'included state agents'
Up to 50 murders allegedly linked to Stakeknife, a British spy within the IRA, included other state agents who had "outlived their usefulness."
Relatives of one of his alleged victims have also accused the PSNI of lacking the "appetite" to investigate his activities, the High Court heard.
The allegations were part of a legal bid to have an external police force investigate the spy.
He was named by the media as Freddie Scappaticci.
The bid will be heard in February 2016.
The judicial proceedings have been brought by the family of Caroline Moreland.
Ms Moreland, a 34-year-old Catholic mother of three, was abducted and murdered by the IRA in July 1994 for being an alleged British informer.
The legal action is seeking to secure a full investigation into the circumstances surrounding a number of killings dating back to the 1980s.
The so-called 'Nutting Squad' was the IRA's internal security unit between 1978 and 1995 and are alleged to have carried out the murders.
The Director of Public Prosecutions called for police to examine Stakeknife's activities, as well as what was known by the RUC Special Branch and MI5.
Relatives have said they are opposed to the PSNI taking charge of the investigation.
At a previous hearing, it was claimed that Mr Scappaticci participated in the campaign in order to strengthen his role as a British spy.
He left Northern Ireland in 2003 after he was named by the media as Stakeknife.
Before leaving his home, he denied being the agent.
Legal counsel for the Moreland family told the court why they were seeking an external police force.
"One of the criticisms is the PSNI don't have any appetite for this investigation because it will necessarily involve criticisms of the security forces," he said.
He claimed that delay had been used to avoid criticism.
"The position is that the families of the various deceased, and we are talking in excess of maybe 50 murders have been reported, are awaiting answers for a very long time," he said.
"The core subject matter of this challenge is the use of a state agent to kill, amongst others, other state agents that had outlived their usefulness in the eyes of the authorities."
Counsel for the PSNI Chief Constable George Hamilton said a final decision was yet to be made on how to respond to the DPP's request.
"He has been engaging with a number of other bodies who may have an interest in the matter and he continues to do so," Mr Hamilton's legal representative said.
The judge listed the application for leave to seek a judicial review for a hearing in February and will review the case again in early 2016.