Officers from the Garda Special Branch are investigating the activities on this side of the Border of the British agent and former head of the Provisional IRA internal security unit Freddie Scappaticci.
Gardaí are gathering information on a number of incidents in which Scappaticci was allegedly involved, including the murder of Co Louth farmer Tom Oliver in July 1991.
The officers are working in tandem with detectives from Operation Kenova, which was set up in Northern Ireland with a budget of £35m (€39m) to probe Scappaticci and, in particular, whether any lives were sacrificed by the security agencies operating there to ensure that his double life as a British agent was not revealed.
As the boss of the Provisionals' internal security unit, more popularly known as "the nutting squad" because of the likelihood that those interrogated by the unit would end up being shot in the head, Scappaticci became what a British army general described as "the golden egg" in the network of agents controlled by the military within the IRA.
Scappaticci spent more than 20 years in the nutting squad before it emerged publicly that he was Agent 6126, codenamed 'Stakeknife', and was being run by a branch of British military intelligence, known as the Force Research Unit.
Operation Kenova was established by British Prime Minister Theresa May, acting on the advice of PSNI chief constable George Hamilton, to investigate allegations 'Stakeknife' was literally allowed to get away with murder to enhance his role as a key spy within the Provisionals.
Kenova was given the budget and a timeframe of five years to complete its inquiries.
It is being led by former counter-terrorist detective and current chief constable of Bedfordshire police Jon Boutcher, who has a 50-strong detective team working with him.
Kenova has so far gathered more than 500,000 pages of material and a large quantity of exhibits while gardaí are also available to co-operate with any requests from the team to brief them on specific incidents here as well as consider any further inquiries considered appropriate.
It is understood the Garda authorities have also appointed a liaison officer to work with Kenova and this role is currently being held by Assistant Commissioner Eugene Corcoran, although he will be shortly leaving to take up a post within the private sector and will have to be replaced.