A top British spy within the IRA allegedly linked to 50 killings is unlikely to ever face prosecution, the High Court has heard.
Counsel for the father of one murder victim claimed Freddie Scappaticci, the west Belfast man named as being the military agent codenamed Stakeknife, will not be brought out of a witness protection programme.
Ashley Underwood QC made the prediction during a legal bid to secure a fresh inquest into the death of Joseph Mulhern in 1993.
Mr Mulhern (23) was abducted, interrogated and shot by the IRA, who accused him of being a police informer.
His body was dumped on a remote hillside near Castlederg, Co Tyrone.
The murdered man's father Frank Mulhern is seeking to judicially review a decision to refer the case to the Director of Public Prosecutions.
He wants a judge to rule that the Attorney General must instead direct a new inquest be held.
Mr Mulhern's lawyers contend there is obligation to investigate under Article 2 of the European Covention on Human Rights.
With no one ever convicted of the killing, they claim the police are aware of evidence that Joseph Mulhern was killed "by or at the instigation of a British agent, Freddie Scappaticci".
Scappaticci left Northern Ireland in 2003 when he was named in the media as being Stakeknife.
Before quitting his home he vehemently denied being the agent who allegedly headed up the IRA's internal security unit, known as the 'nutting squad'.
In October last year DPP Barra McGrory QC called for police to examine Stakeknife's activities, along with what was known by RUC Special Branch and MI5.
Chief Constable George Hamilton has since decided detectives from an outside force should handle an inquiry that could last five years and cost up to £35m.
In court yesterday Mr Underwood claimed there was no realistic prospect of a prosecution.
He said: "Scappaticci vanished from his home in Belfast in 2003.
"He's believed to have joined a witness protection programme and be living under an assumed name.
"That does not give one to believe anybody is going to bring him before a court."
He also cited police resource issues as a potential further stumbling block into fully investigating Stakeknife's alleged role in 50 murders.
Mr Justice Maguire described his assessment as "pessimistic" and stressed how those wanted can be brought back into the jurisdiction.
He commented: "If I were him (Stakeknife) I'm not sure I would be completely happy in bed at night, would it ever flicker in my mind that people might be coming for me at some point?"
David Scoffield QC, for the Attorney General, argued that the legal challenge was premature.
The hearing continues.