The police service in the North has said it will not interfere with an investigation into a high-ranking British army agent in the IRA.
The agent, known by his code name Stakeknife, has been linked to more than 50 murders.
The probe - dubbed 'Operation Kenova' - into the crimes is to be funded by the PSNI but staffed by external officers.
It will be led by the Chief Constable of Bedfordshire Police Jon Boutcher.
Investigators will also examine possible crimes by IRA members, other agents, and army or police handlers that emerge during the course of their work.
The probe is expected to take at least five years and cost almost €40 million.
Mr Boutcher today said he will leave "no stone unturned" in investigating the killings:
Chief Constable George Hamilton said: “After taking a number of issues into consideration, I have decided that a team resourced with external officers and staff funded by the PSNI is the most appropriate way forward, given the size, scale and complexity of the investigation."