A man who was being questioned about the murder of Northern Ireland prison officer David Black has been released without charge.
The 51-year-old was arrested on Monday.
A file is being prepared for the Director of Public Prosecutions.
The man was being held at Ballyconnell Garda Station in Co Cavan in connection with dissident republican activities and the murder of Mr Black last year.
The 52-year-old father-of-two was shot dead while driving to work at Maghaberry Prison in Lurgan on 1 November 2012.
A 34-year-old man who was arrested in connection with the same investigation remains in custody at Cavan Garda Station.