A man has died in a cell at Monaghan Garda Station.
His body was removed to Cavan General Hospital where a post mortem examination revealed he died of natural causes.
Gardaí say the 40-year-old was detained at around 1.30am this morning following a row. He was found unconscious in the cell shortly after.
A doctor was called but all efforts to resuscitate the man failed, and he was pronounced dead at the scene.
Meanwhile, the NI Police Ombudsman is investigating the circumstances surrounding the death of a man in Lisburn police station this morning.
The man, who was 21 and from Lisburn, died at around 4am. He had been arrested several hours earlier.
Police Ombudsman investigators have taken statements from witnesses who were in the station at the time.