A decision on whether to charge Gerry Adams over the abduction and murder of Jean McConville is expected within weeks, the Belfast Telegraph can reveal.
The Sinn Fein president was arrested on April 30, 2014 and questioned by police for four days before being released.
The PSNI file has been handed to Northern Ireland's Public Prosecution Service (PPS), which will decide whether to charge the 65-year-old with any offence.
Mr Adams has always vehemently denied allegations levelled by former republican colleagues that he ordered the murder of the west Belfast widow in 1972.
A PPS spokeswoman said the case is under "active consideration" with a decision due in weeks.
Over a year has passed since Director of Public Prosecutions Barra McGrory QC delegated the case to his deputy, Pamela Atchison, because he acted as Mr Adams' lawyer prior to becoming DPP.
However, BBC reports have suggested there is "insufficient evidence" to pursue a prosecution.
Mr Adams' arrest triggered a major row at the heart of Northern Ireland's power-sharing institutions, with Sinn Fein accusing an anti-peace process "rump" in the PSNI of orchestrating the arrest, branding it an example of "political policing" timed to damage the party's chances in the forthcoming European and local government elections.
Those claims were emphatically rejected by Prime Minister David Cameron, Stormont First Minister Peter Robinson and Justice Minister David Ford.