Investigators are appealing to anyone who was in the area at around 4.15am to come forward.
The Garda Ombudsman Fiosrú is investigating the circumstances surrounding the death of a man in Dublin city last week.
An incident involving the serious harm of a 51-year-old man on O'Connell Street in the early hours of last Friday the 15th of August was referred to Fiosrú.
The man has since died and a post mortem exam is due to be carried out.
Investigators are appealing to anyone who was in the area at around 4.15am to come forward.

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