Drugs are suspected to have played a part in the deaths of two inmates in Limerick and Wheatfield prisons.
A 25-year-old, who was reportedly serving a sentence for manslaughter, was found in his cell in Limerick Prison at around 4am this morning.
His body was taken to Midwest Regional Hospital where a post mortem is due to be carried out.
Meanwhile, according to the Irish Times, on Christmas Eve a 23-year-old man, who was in custody pending a court appearance, was found dead in his cell in Wheatfield Prison.
Investigations into both deaths are underway.