An investigation has been launched after the death of a man at Cloverhill Prison.
A man in his late 30s died after what Garda described as an incident between two male prisoners at the Dublin facility shortly after midnight.
The man was treated by emergency serves but pronounced dead at the scene a short time later.
A full forensic and technical examination will take place.
Gardai say they are following a definite line of inquiry and the investigation is ongoing.