The Irish Prison Service and the Gardai say they're investigating the death of an inmate at Mountjoy Prison.
A man in his 30s died in the early hours of this morning, after falling ill in his cell.
He was found unconscious and taken to the Mater Hospital but died a short time later.
A post mortem will be carried out to determine the cause of the man's death - but it's believed he died from a drugs overdose.
