John Ustic's body was found at his home on Monday
Gardaí are appealing for witnesses, in relation to a fatal assault in Skibbereen in West Cork.
The murder inquiry was launched last night following a post mortem on the body of John Ustic.
The body of the 51 year old English man was discovered by his partner on Monday morning at the house they were renting on High Street in Skibbereen.
Initially Gardaí weren't ruling out the possibility that he died due to a fall, as there was no sign of a forced entry at the house.
But the results of a post mortem carried out yesterday concluded that he died as a result of an assault.
Detectives are now appealing for information from people who were in the High Street area of Skibbereen between 7.30 and 10.30 on Sunday night.