The deceased has been named locally as father of one Michael Knapp Ryan from Limerick.
A spokesperson for the Irish Prison Service confirmed the sudden death of a prisoner in Limerick Prison on December 25th.
In a statement they said "All deaths in custody are investigated by the Irish Prison Service, the Inspector of Prisons and An Garda Síochána, where circumstances warrant.
"The cause of death is determined by the coroner’s office. The next of kin have been notified’’.
The deceased has been named locally as father of one Michael Knapp Ryan (34) who was from St Mary's Park in Limerick city.
Mr Ryan had a number of convictions for violent disorder.
In 2013 he was given a 4-year sentence for attacking a man with a slash hook.
He is survived by his mother Diane, sisters Maria, Donna, Joanne, Carina, Sarah and Sherice and brother Daniel, Kieran and Ricky.
His requiem mass will take place on Saturday December 31st with burial afterwards in Mount St Oliver’s Cemetery.
Writing on RIP.ie, a number of Ryan’s friends have posted messages of condolence to his family.
One user wrote: "Gone way too soon Micheal u will get the best bed in heaven watch over ur mam maria and baby Micheal and family fly high.”
While another penned: “Rest easy Micheal gone way to soon watch over ur son and family at this sad time xxx rest in peace bro from your pals Christopher and Jonathan x till we meet again.”
The number of prisoners who died in custody so far this year is almost double the annual figure of 2021.
In figures released in Septmeber – before Mr Knapp Ryan’s death –The Department of Justice confirmed fifteen people have died in prison in 2022.
This compared to eight such deaths noted for all of 2021, according to figures provided by Minister for Justice Helen McEntee to Aontú leader Peadar Tóibín.
In addition to the 15 deaths in prison, one person died while on temporary release from custody earlier this year.
Among the 15 prisoners was Robert O’Connor (34), of Snowdrop Walk, Darndale, Dublin, who died in hospital last month following an attack in Mountjoy Prison.
Mr O’Connor’s death is now the subject of a murder investigation.