The victim, aged in his 20s, moved with his family to Ireland several years ago and been living on the outskirts of Killarney town.
He is a former student at St Brendan’s College and is well known in the town.
He has been in a very serious condition at Kerry General Hospital since he was found unconscious shortly after 10.30pm on Wednesday.
Gardaí and emergency services were called to the Killeen Woods estate where they discovered the man lying in the front lawn of the property. It is believed a party had been ongoing in the house.
The man was taken by ambulance to hospital where his condition was initially given as serious but is now described as critical.
Forensic tests have taken place at the scene and investigating gardaí are appealing for witnesses to come forward.
They are particularly anxious to hear from anyone who was in the house or in the vicinity of Killeen Woods between 10.00pm and 11.00pm on Wednesday.
Two men were arrested in connection with an alleged assault and they have both been released without charge. A file will be prepared for the Director of Public Prosecutions.
Anybody with any information that might be of assistance is asked to contact Killarney Garda Station on 064-6631222; Tralee Garda Station on 066-7102300 or the Garda Confidential Line on 1800-666-111.