The British police officer investigating murders and other crimes linked to the IRA double-agent Stakeknife has promised he will go where the evidence leads him — even if it involves members of the security services and senior figures in the republican movement.

Bedfordshire Police Chief Constable Jon Boucher, who was appointed to take charge of the inquiry last year, today made a fresh appeal for information to those who can provide assistance.

Stakeknife was the code name given to the individual within the IRA who was in charge of its internal security unit, linked to dozens of murders over a 20-year period, while at the same time acting under the supervision of British intelligence as a double agent.

In 2003, Belfast-man Freddie Scapaticci denied that he is Stakeknife.

He has not been seen in Northern Ireland for several years and the authorities will not confirm whether they are aware of his current whereabouts.

Mr Boucher and his team have spent several months doing preliminary work in an investigation that could last up to five years.

He is now appealing for help from those with information about the activities of Stakeknife and who may have had a peripheral role in his crimes.

Speaking to RTÉ News, Mr Boucher said: "We're here to identify those people who committed the offences of violence and torture and murder.

"I will look favourably on anybody who comes forward.  Even if they are involved in minor criminality, I will do everything I can with regards to any potential prosecution."

He continued: "Let's be clear. This investigation will go wherever the evidence takes us.

"So whether that's people who are involved in public life now, whether they are senior members of the security forces, who knows. 

"We will go where the evidence takes us," he concluded.