This is the inmate who died in the early hours of this morning after he was brutally assaulted in Mountjoy prison last week.
Robert O'Connor, 34, suffered a bleed to the brain after he was targeted by up to four men in a cell at the Dublin jail last Friday evening.
He was rushed to the Mater Hospital, where he remained on life support before a decision was made to turn it off this morning.
Read More: Victim of brutal Mountjoy Prison attack dies as Garda probe continues
Investigators are probing if O'Connor was targeted on the orders of a Kinahan hitman relating to a dispute outside of the prison but other theories are also being explored.
Gardai are now treating the investigation as murder.
The victim, from north Dublin's Darndale, had been in Mountjoy since last October serving time but was handed down a six-and-a-half year sentence last Wednesday at the Criminal Courts of Justice for the possession of a loaded pistol.
A post mortem examination is taking place on his body today.
A garda spokesman said: "Gardai are continuing to investigate the serious assault of a man (30s) that occurred on the evening of Friday, 29th July, 2022, at Mountjoy Prison in Dublin.
"The man was receiving treatment for serious injuries at the Mater Misericordiae University Hospital and passed away in the early hours of this morning, 3rd August 2022.
"A post mortem is scheduled to take place later today the results of which will determine the course of the investigation.
"Investigations into this matter are ongoing."
The Irish Prison Service is also carrying out its own probe.
A spokesman for the IPS said: "The Irish Prison Service can confirm that the prisoner who was seriously injured in an incident in Mountjoy Prison on Friday 29th July 2022 has died.
"We extend our deepest sympathies to his family and friends.
"The incident continues to be investigated by the IPS and the Gardai.
"All deaths in custody are subject to investigation by the Inspector of Prisons."
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