An inmate who died in Maghaberry jail yesterday is now the fourth person to lose their life in a Northern Ireland prison this year.
The Department of Justice confirmed the 57-year-old man died yesterday morning and his family have been informed.
The PSNI, Coroner and Prisoner Ombudsman have launched investigations into the death.
Ronnie Armour, Head of the Northern Ireland Prison Service, said: "I would like to extend my sympathy and that of the Northern Ireland Prison Service to the family of the prisoner. My thoughts are with them at this difficult time."
Three other prisoners have lost their lives in Northern Ireland this year.
In Maghaberry, a 38-year-old remand prisoner died in May, while two others lost their lives in Magilligan prison in Co Londonderry - a 44-year-old man in March and a 27-year-old man in August. In the last 10 years, 40 deaths have been recorded in Northern Ireland's prisons.
Last month, serious concerns were raised about the care provided to vulnerable inmates at Maghaberry. A report by Criminal Justice Inspection Northern Ireland said key lessons had not been learned despite a string of critical reports into deaths in custody and incidents of self-harming.