The body of David Farish was found at his home in the town's Broadlee Bank at about 13:30 on Thursday.
Police Scotland said officers had been alerted by an anonymous phone caller who quickly hung up.
Following a post-mortem examination, the death is now being treated as murder.
Det Insp David Pinkney, from Police Scotland's Major Investigation Team, said: "At this time we are in the initial stages of our inquiries to establish the full circumstances surrounding David's death.
"However, as a result of the investigative and forensic work already carried out, we are satisfied that he has been murdered.
"David was last seen alive at 8.15am on Tuesday 16th February prior to officers finding his body at 1.30pm on Thursday afternoon, and anyone with information as to his movements between this time period is urged to come forward."
He added: "Police Scotland was alerted to David's body being within his flat by an anonymous caller who hung up quickly without leaving any details. I would request that individual to urgently get back in touch and help us with our investigation.
"In addition, anyone who has seen any suspicious activity within the Broadlee Bank area between Tuesday 16th and Thursday 18th February should also contact police immediately."
A murder investigation has been launched following the death of a 75-year-old man in Galashiels in the Scottish Borders.