17/10/2016 3:15 PM AEDT | Updated 17/10/2016 6:53 PM AEDT

Former NSW Top Cop Joins IRA Murder Probe

Nick Kaldas is on a steering committee looking into the crimes of infamous double agent "Stakeknife".

Former NSW Deputy Police Comissioner Nick Kaldas has joined a probe into a notorious British double agent linked to 50 murders.

A former NSW top cop has been recruited to help a Northern Ireland probe into the actions of a suspected British spy called "Stakeknife", an infamous operative who reportedly infiltrated the Provisional IRA and was linked to more than 50 murders.

Former NSW Deputy Commissioner Nick Kaldas is one of six policing experts on a steering committee for Operation Kenova, which is examining whether there is evidence of Stakeknife's involvement in a series of murders, attempted murders or unlawful imprisonments attributed to the Provisional IRA.

As part of the IRA's internal security unit -- know as the "nutting squad" -- Stakeknife is alleged to have been involved in more than 50 murders. At the same time, he was allegedly working for British military Intelligence.

Reuters Photographer / Reuters
Graffitti off a side street off the Falls Road, Belfast, relating to Real IRA man Joe O'Connor who was shot dead in 2000, taken in 2003 after "Stakeknife" was allegedly unmasked.

Stakeknife was named in the British press as the most senior army operative inside the IRA during the 1980s, and was widely identified in 2003 as west Belfast man Fred Scappaticci. He has always strongly denied he was an agent.

Kaldas, who announced his retirement from the NSW police in March, will join five former high ranking police and justice officials as part of Operation Kenova.

"It's a very comprehensive, complex investigation going over decades."Nick Kaldas

"(People) want to know what happened to their loved ones," Kaldas told the ABC on Monday.

"I was grateful for the opportunity to participate. I am hoping to contribute with my background in homicide and international investigations.

"I am keeping a very open mind about who or what was involved in these murders."

Kaldas has international experience in murder investigations, having been Chief of Investigation in the UN Special Tribunal for Lebanon in 2009, where he led the investigation into the assassination of Lebanese prime minister Hariri and 21 related murders.

Nick Kaldas will join five former high ranking police to sit on a steering committee for Operation Kenova

Operation Kenova is also examining the activities of current and former police officers and members of the military and security services, as well as former members of the IRA.

In early 2015 the family of west Belfast man Patrick Trainor, believed to have been killed by Stakeknife, spoke out for the first time about the 28-year-old's abduction and murder in February 1981.

Trainor was accused of being an informer, but his family believe he was sacrificed to protect Stakeknife.

The father-of-three's body was found blindfolded, shot and covered in burn marks in west Belfast.

Bedfordshire Police Chief Constable Jon Boutcher, who is in charge of Operation Kenova, said this week the inquiry had heard new evidence.

"This week we have heard things that from what the families have told me they have never told anyone before, because nobody has asked them," Boutcher told Sky News.

"What I have been told this week is significant evidence against the people responsible for these offences."