Prison authorities have launched separate investigations into the deaths of two prisoners in the space of 24 hours.
Michael Keating, who was serving a two-and-a-half year sentence for theft in the Midlands Prison, was found dead in his cell at 6.30am yesterday. A prison spokesman said Mr Keating, who was in his thirties, was "unresponsive" and later declared dead at the Midlands Regional Hospital in Portlaoise.
Prison authorities were last night still awaiting the results of a preliminary post-mortem examination on Mr Keatings remains.
However, the Prison Service said foul play is not suspected in his death. Mr Keating's family has been informed.
On Friday, another prisoner, Douglas Ward (38), was found dead in his cell in Dublin's Mountjoy Prison by warders who were beginning their morning rounds.
Mr Ward (38), who was convicted of the manslaughter of Dundalk man Niall Dorr (18), was declared dead in his cell at 6.40am on Friday. A cause of death was not revealed but the Prison Service said foul play was also not a suspected cause in this death.
Ward, from Knockbridge, Co Louth, was originally jailed for 13 years for the manslaughter but this was reduced in January to 10 years by the Court of Appeal.
The court heard that Mr Ward, a father of three, had substance abuse and alcohol problems, and had carried out a prolonged and vicious assault on Mr Dorr at Castle Street in Dundalk in October 2010.
His trial heard Ward attacked, punched and kicked the youth, bouncing his head off a road several times in an unprovoked attack.
State Pathologist Dr Marie Cassidy gave evidence that head trauma and a fracture to Mr Dorr's skull which caused haemorrhaging was consistent with his assailant stamping on his head.
Separate investigations are under way into both deaths with reports to be prepared by the Prisons Inspectorate.