The bludgeoned body of Anthony McErlain was discovered in an upstairs neighbour’s flat in Broombeg View in Ballycastle around 8.30 pm on Thursday.
Police said the 48-year-old suffered a “traumatic and frightening death” and described the killing as “a heinous crime”.
Detective Chief Inspector Gareth Talbot said police were still waiting on results of a post-mortem examination.
A 33-year-old man was arrested at the scene on Thursday night.
A 50-year-old man was arrested yesterday for questioning.
DCI Talbot said: “The investigation team is extremely keen to speak to witnesses or anyone who may have spoken to Mr McErlain over recent days.
“We would especially like to hear from anyone who was in the Broombeg area at any time between 17:00 and 20:30 yesterday and who may have witnessed or overheard an altercation or disturbance, in or around number 4 Broombeg View.”