Police have named the man who was tragically found dead in a flat in the Crebilly Road area of Ballymena as 33 year old Donald Fraser-Rennie.
Two men, aged 29 and 33 years old, who were arrested on suspicion of murder, remain in police custody.
Detective Chief Inspector John Caldwell said: “My thoughts are with Donald's family and his fiancée at this very sad and difficult time.
“At this stage I believe that Donald was the victim of a vicious, sustained and violent beating which resulted in his death.
“I am appealing to anyone who has information that could assist with the investigation to contact us.
“ I am also keen to speak to:
“Anyone who had been in contact with Donald at any time between yesterday, Tuesday, 29 September and 1.00am this morning, Wednesday, 30 September.
“Anyone who was in the Crebilly Road between mid-day yesterday and 1.00am this morning.
“I am particularly keen to establish whether witnesses saw or heard anything suspicious.
"I would ask anyone who has any information, no matter how inconsequential you may think it is, to contact detectives on the non-emergency number 101, quoting reference 52 30/09/20. Alternatively information can also be provided anonymously to the independent charity Crimestoppers on 0800 555 111. "