Mystery surrounds the death of a middle-aged man whose body has been found in a block of sheltered housing flats in central Oxford.

Police and forensic scientists last night (Tuesday, September 13) scoured Luther Court, off Speedwell Street, and a flat believed to be the home of Michael Alistair Calvey.

Friends of Mr Calvey alerted police after they became alarmed that he had not been seen for four days -- since last Friday -- but are baffled by graffiti that is claimed to have been scrawled on the entrance to his flat.

A close friend of Mr Calvey's told the Oxford Mail the words "Alistair, you're dead" were daubed on his door, but that has not been confirmed by Oxford police who last night had not released the name of the dead man and said they were not treating the incident as a murder inquiry.

Mr Calvey's friend, who did not wish to be named, said: "This is a guy who had mental health problems but who always kept himself to himself and was the sweetest man you could ever wish to meet.

"He would go to the Wharf House to drink and Sainsbury's -- and that was it. But he has always been vulnerable. I can't imagine him having any enemies.

"Alistair would not have done anything to warrant any threats whatsoever, let alone a death threat, because he was the most unthreatening bloke you could ever wish to meet."

A police spokesman said: "We have attended an unexpected death -- and CID and scenes of crime officers attended as a matter of course."