The Smithwick Tribunal, which is investigating claims of garda collusion in the deaths of two senior RUC officers, has sought another extension of time to hear evidence and write a final report.
Judge Peter Smithwick had been expected to present a final report last November but following a request for additional time was given an extension to the end of this month.
He is now seeking a further five-month extension.
The Smithwick Tribunal was set up in 2005 and began investigating the deaths of Chief Supt Harry Breen and Supt Bob Buchanan a year later.
They were killed by the IRA minutes after leaving a meeting in Dundalk Garda Station in March 1989.
The tribunal is seeking to establish if a garda colluded with the IRA in their deaths.
Public hearings got under way last June and it had originally been expected Judge Peter Smithwick would present a final report in November.
However, he sought and was given an extension to the end of this month.
Now the judge has written to the clerk of the Dáil seeking a second extension - this time for five months.
It is necessary, he said, to hear crucial evidence from one of the former gardaí accused of collusion but who is now ill.
The extension also includes the four months the judge says he will need to prepare the final report.
The tribunal has cost in excess of €9m.
