The prison service has confirmed a man has died in Magilligan jail.
He was 27-years-old and he passed away on Friday morning. His next of kin have been informed.
As with standard procedure, the PSNI, Coroner and Prisoner Ombudsman have launched investigations into the death.
A post mortem is to take place to determine the cause of 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."