The garda watchdog is investigating the death of a man who collapsed at Ballymun Garda Station just as he was being released from custody.
The man, who was in his mid-20s, had been arrested early on Saturday morning and taken to the station for questioning.
While there, he was offered medical assistance because gardai felt he was unwell.
But reports state he refused an ambulance.
Later, shortly after he was released but while he was still at the station, he collapsed.
Medical assistance was provided and he was transferred by ambulance to the Mater Hospital, where he was pronounced dead at around 4.30am.
The incident was referred to the Garda Ombudsman for independent investigation as per Section 102 of the Garda Siochana Act 2005, which provides for cases where death or serious harm occurs to a person following their involvement with police.
It is understood that the man was first arrested under the mental treatment act.
The garda ombudsman investigation is routine following the death of a person who has been in recent contact with the gardai.