Bedfordshire Chief Constable Jon Boutcher (left) is leading Operation Kenova, the investigation into the activities of the alleged Army agent known as Stakeknife.Police Service of Northern Ireland

The officer leading the Stakeknife investigation has been assembling a group of some of the most senior figures in international policing to act as advisors on the case.

Bedfordshire Chief Constable Jon Boutcher, who is heading Operation Kenova, an investigation into several IRA murders and the role of alleged Army agent known as Stakeknife, has been gathering an outside detective team of nearly 50 officers as well as an Independent Steering Group.

NYPD Deputy Commissioner for Intelligence and Counter-terrorism John Miller and Mike Downing, Deputy Chief of the Los Angeles Police Department, will join the group, which will also include Kathleen O’Toole, part of the Patten Commission, former Police Ombudsman Dame Nuala O'Loan, Iain Livingstone, who is Deputy Chief Constable with Police Scotland, and Nick Kaldas a former Deputy Commissioner of Police in New South Wales who has been working with the UN.

Said Boutcher: “Each of those members has experience of complex investigations that will have engaged similar legal challenges and have involved historical cases.”

He said the group is to act as a “sounding board” or “critical friend.”

"There is an absolute determination to get to the truth for the families," he said - and he promised "a meaningful, honest, authentic investigation to get to the heart of what happened".

Stakeknife is the code name for the Army agent who infiltrated the IRA, operating inside its “internal security,” the division of that organization responsible for the interrogation of suspected informers often leading to execution.

Freddie Scappaticci, a Belfast republican interned in the 1970s, has denied he was the agent, reports.

The investigating team will begin by assessing relevant documents and information held across the intelligence agencies—Military, MI5 and the then RUC Special Branch.

Boutcher has been meeting families to brief them on the progress and has also assembled a Victims Focus Group to advise the investigation.

“I am committed to doing all I can to find the truth for the victims and their families. It is them who we should be thinking of throughout, said Boutcher, when he received the appointment in June.

“It must be extremely hard to have listened to various commentaries within the community and the media about how and why their loved ones died. I hope this investigation ultimately addresses the uncertainties and rumours. All I can promise is an absolute commitment to pursuing the truth.”