The body of Alan Whitelaw, 39, was discovered at his tenth-floor flat in Glenfinnan Road in the Maryhill area of Glasgow just after midnight on Wednesday.
Police Scotland have now launched a murder inquiry and asked anyone with information to contact officers.
Detective Inspector Fil Capaldi said: "Mr Whitelaw suffered a brutal and sustained violent attack.
"I have no doubt that someone in the block of flats would have heard the disturbance take place and more than likely saw someone leave either the floor or the flats in a hurry, possibly dishevelled or with blood on them.
"From our investigations so far, we know that there was a disturbance outside Mr Whitelaw's flat between 6pm and 7pm. Whether this had progressed into his flat or whether a further attack took place later in the evening has still to be established."