DETECTIVES in the Republic investigating the murder of Detective Garda Adrian Donohoe have been released without charge.
Det Garda Donohoe was shot dead last month during an armed robbery in a credit union in Co Louth.
The married father-of-two and a colleague were ambushed a criminal gang as they escorted cash to the credit union.
As the detective got out of his car, a gunman fired a shotgun at him, hitting him in the head.
Gardaí say investigations are ongoing into one of the biggest inquiries carried out by the force in recent years.
The men, aged in their 30s and 70s, were arrested on Friday morning at a house near Dundalk as gardaí carried out six separate searches.
Detectives believes a number of those involved in the murder are part of a criminal gang from Northern Ireland.
Within hours of the murder, PSNI detectives called at the homes of a number of suspects in Newry and Warrenpoint, Co Down.
However, none of the suspects were at home.
A getaway car, a stolen Volkswagen Passat estate, was later found burned out in Co Armagh.
Gardai believe one of those involved in the armed robbery was a teenage girl.