Thomas Griffin, 31, from Ballyfermot, Dublin, was fleeing attackers in the Irish National War Memorial Gardens in Islandbridge by trying to swim across the Liffey when he got into difficulty.

He managed to reach the riverbank on the Chapelizod Rd side and arriving gardaí and emergency services went to his aid. He was taken to St James's Hospital, where he was subsequently declared dead.

Serious knife injuries

Mr Griffin had suffered serious knife injuries in a row in the gardens before he entered the water. The incident occurred on May 30.

The Irish Examiner understands that the man who died in garda custody on Saturday had been arrested in relation to the investigation into the assault of Mr Griffin.

The Fiosrú team is conducting an investigation into the circumstances leading up to this man’s death.

Samples will be taken from the deceased to determine if there were any substances in his body that might have contributed to his death.

An examination of the deceased's clothing will also be taken to test for the remains of anything he had in his pockets.

CCTV footage from inside the garda station will also be examined, and arresting gardaí and members in the station who interacted with him will be spoken to.

'Unresponsive in a cell'

A statement issued by Garda HQ said: “On Saturday June 6, 2026, a man in his 30s who was in garda custody at a garda station in Dublin became unresponsive in a cell and urgent assistance was requested.

“Despite immediate resuscitative attempts by garda members and by medical personnel and first responders who attended, the man was later pronounced deceased.” 

It said the coroner was notified.

The coroner, in consultation with Fiosrú, will determine what medical examinations and tests are necessary.

The statement said: “As per garda policy, this matter has been referred to Fiosrú, the Office of the Police Ombudsman, under Section 203(1) of the Policing, Security, and Community Safety Act 2024.

“As this matter is being investigated by Fiosrú, An Garda Síochána is not in a position to comment.”

Fiosrú confirmed it had received a referral from An Garda Síochána, adding that its staff attended the scene. It said it could issue no further comment as the matter is now under investigation.

• Cormac O'Keeffe is the Security Correspondent with the Irish Examiner.