A man in his 30s, who was arrested as part of the investigation into the murder of Detective Garda Adrian Donohoe, has been released without charge.
The man was arrested on 19 April and was questioned by detectives in Dundalk all week.
He was released without charge this evening and a file will be prepared for the Director of Public Prosecutions.
Detective Garda Donohoe, 41, was shot dead outside Lordship Credit Union near Dundalk on 25 January, 2013.
Gardaí say the investigation is ongoing.