Four people, including two former MI5 officers, are not to be charged after a major investigation into the Army agent within the IRA known as Stakeknife.
The decisions have been announced by the Public Prosecution Service (PPS).
The PPS considered the four - who also included alleged agent Freddie Scappaticci - for charges of perjury and misconduct in public office.
It said there was "insufficient evidence to provide a reasonable prospect of conviction".
The BBC understands one of the other individuals is a former deputy director of PPS, Pamela Atchison, who has previously stated she acted appropriately at all times.
In her case, the PPS said "there was no evidence of any bad faith or impropriety in terms of how the prosecutor sought to fulfil their responsibilities".
The multi-million pound Operation Kenova investigation was launched in 2016 and involved dozens of British police officers examining the activities of the agent Stakeknife.
The individual is alleged to be west Belfast man, Freddie Scappaticci, 73, who denies being the Army agent who operated at a high-level within the IRA for years.
He left Northern Ireland when identified by the media in 2003.
The investigation was overseen by the retired chief constable of Bedfordshire, Jon Boutcher and a central element was the potential complicity of the state in multiple murders and other criminality.
In October 2019, files of evidence relating to numerous individuals were sent to the PPS.
In a statement, the PPS said today's decisions were connected with an allegation that an individual committed perjury in the course of making affidavits sworn between 2003 and 2006.
Although not named by the PPS, this is believed to relate to Mr Scappaticci.
The PPS added they also dealt with the circumstances in which a decision was subsequently taken not to prosecute that individual in 2007.
Further files from Operation Kenova are still being considered for decisions relating a range of potential offences including murder, false imprisonment and assault.
Decisions on these additional matters will issue in due course, the PPS said.
'No major surprise'
KRW Law, which acts for several families impacted by Stakeknife's activities, said there was "no major surprise" in the decision.
Solicitor Kevin Winters said if the "outworkings" led to a report from Mr Boutcher being published sooner then "much of the frustration felt by families will dissipate quickly".
Mr Boutcher has said he cannot release a report on his investigation until any criminal proceedings are out of the way.
Mr Winters added: "If anything, today's decision increases the pressure on him to deliver the sort of findings that will give families some degree of closure."