Police are appealing for people who saw a man before he died suddenly in Corby to come forward.
Officers investigating the death of John Gunn, 46, have asked anyone who saw him on the day before he was admitted to hospital to come forward.
Mr Gunn was taken to Kettering General Hospital on Sunday, January 12, after members of his family had trouble waking him.
He died at the hospital two days later and subsequent tests have since revealed he sustained a head injury before his death.
Detective Inspector Ali Reynolds said: “At this stage, we’re keeping an open mind on whether Mr Gunn was assaulted or had an accident.
“But we are extremely keen to trace his movements on Saturday, January 11, and would like to speak to anyone who saw him at that time.”
Anyone with information can contact Northamptonshire Police on 101 or call Crimestoppers anonymously on 0800 555 111.