Four people, including two former MI5 officers and a former prosecutor, will not face criminal proceedings as part of a major investigation into a top British spy within the IRA.
Prosecutors in Northern Ireland said that the fourth person, understood to be Stakeknife, the high-ranking Army agent within the IRA will not face a charge of perjury.
The Public Prosecution Service considered charges including perjury and misconduct in public office.
In 2003, Stakeknife was named as Belfast man Freddie Scappaticci. But he has always strongly denied it and rejects claims that he was an IRA informer.
Video report by UTV correspondent Sharon O'Neill:
Stakeknife had been accused of lying under oath in affidavits between 2003 and 2006 following files sent by the Operation Kenova team, who are investigating killings allegedly linked to the agent.
The two former members of the British security service and the former PPS prosecutor were considered for misconduct in office.
The PPS also said it reviewed the circumstances in which a decision was taken not to prosecute Stakeknife in 2007.
The director of public prosecutions Stephen Herron said these are the first decisions relating to files submitted by Operation Kenova, the investigation team led by former chief constable Jon Boutcher.
Mr Herron said: "In respect of these initial perjury related matters, I have carefully considered the evidence provided by Operation Kenova investigators in relation to the four individuals reported.
"After a thorough analysis of all available evidence, and with the benefit of independent advice from highly experienced Senior Counsel, I have concluded that in each case there is insufficient evidence to provide a reasonable prospect of conviction for any offence."
Mr Herron said that the Evidential Test for Prosecution was not met.
"The second limb of the Test for Prosecution, which relates to the public interest in bringing proceedings, did not therefore fall to be applied," he added.
"There are constraints on being able to fully explain my decision making rationale at this time.
"In view of this, I wish to assure the public that decisions have been taken with absolute independence and impartiality and fully in accordance with our Code for Prosecutors."
Mr Herron stressed that prosecutorial consideration of all remaining matters is ongoing. He added that families directly affected by these cases will be kept informed as they progress.
However, Mr Boutcher said that today's decision does not mean prosecutions are out of reach.
"The challenges of bringing a prosecution for Northern Ireland legacy cases, both from a legal and practical perspective, are well-known and have been described in my evidence to the Northern Ireland Affairs Select Committee," he said.
"We await the remaining decisions with keen interest.
"Most importantly, at the outset of Operation Kenova, I made commitments to provide families with our findings as to what happened in their individual cases and to deliver a public-facing report. These two key commitments remain at the forefront of our endeavours.
"Legacy should not be judged simply through the prism of prosecutions, it must be considered as a process which provides the truth to those families who have lost loved ones."
The wider Operation Kenova is continuing to investigate activities connected to Stakeknife including murder, false imprisonment and assault.