The assault happened on Sunday morning.
Gardaí investigating the fatal assault that occurred in Killorglin in Kerry in the early hours of Sunday morning have arrested a man in connection with the assault.
A male in his 20s was arrested in on Thursday morning and is currently detained under the provisions of Section 4 of The Criminal Justice Act.
The victim, named locally as Stephen O’Connor, was critically injured during an incident outside a fast-food outlet at around 2.20am on Sunday.
A post-mortem examination has been completed on the body but details are not being released for operational reasons.
Stephen’s family have asked for privacy at this time.
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