Chief Constable George Hamilton made the comments at a terror victims conference hosted by the South East Fermanagh Foundation (SEFF) in Enniskillen on Saturday.
The top officer at first empathised with victims on their feelings that investigations into the murders of their loved ones are being “shunted to the side whilst other cases, many of which involved state actors seem to be getting progressed. I understand such perceptions”.
He added: “But the reality is that the work of the PSNI’s legacy investigation branch is largely determined by circumstances outside my control.”
One of the key reasons for this, he explained, was an issue that had arisen recently, which resulted in the Director of Public Prosecutions Barra McGrory sapping up the majority of the resources that would otherwise be available to investigate terror victims’ cases.
Mr Hamilton said: “Under section 35 of the criminal justice act - the Justice (NI) Act 2002 - there is a duty on me when requested by the director of public prosecutions to supply information, to ascertain facts and report to him.
“Now the rest of us ordinary folk would call that an investigation, so effectively that is what it is. There are some circumstances where the director of public prosecutions can direct me to effectively conduct an investigation. There are other fluffy words around that, but that is in practice what it means.
“And it is actually in those cases that the majority of my legacy investigations branch officers are occupied at the moment.
“With finite resources available I have no option but to fulfil those legal obligations.”
Other cases which Mr Hamilton has been legally obliged to investigate, he said, include Bloody Sunday, the Military Reaction Force, the Boston College tapes and the ‘on the run’ letters scheme.
A Public Prosecution Service (PPS) spokeswoman did not contest Mr Hamilton’s assertions.
“The director of public prosecutions has the power to request the chief constable to investigate any matter where it is believed an offence has been committed against the law of Northern Ireland,” she said.
“This is a responsibility which the director exercises in cases of utmost gravity which may have been referred through a number of channels, including the Northern Ireland Attorney General, the inquest system and Police Ombudsman investigations.
“Several of the cases referred arise from decisions of the Court of Appeal quashing convictions on the basis that important and significant information was deliberately withheld from previous directors in the exercise of their prosecutorial function, thereby causing miscarriages of justice.”
She also noted that the chief constable highlighted a number of competing legacy pressures on his budget, including cases referred by the PPS director.