Gardaí are investigating the circumstances surrounding the death of a senior detective at Ballymun Garda Station.
The man's body was found in his office yesterday evening.
The State Pathologist's Office has been informed and the scene has been preserved.
It is believed an official firearm has been recovered.
A chief superintendent from outside the division is expected to be appointed to take charge of the case.
The Garda Síochána Ombudsman Commission has also been informed.
The man, who was in his 50s, was one of the senior investigators in the Regency Hotel murder case.
Foul play is not suspected.