A friend of the tenant became worried when he was unable to reach the man for several days, and contacted authorities.
Police found the body on Sunday afternoon, after breaking down the door. Police spokesman Patrick Maierhofer told the Austrian Press Agency that marks were found on the man's neck and so his death is being treated as suspicious.
A formal identification is necessary before they can confirm the identity of the man.
Police believe the body most likely lay undiscovered for several days. An autopsy is scheduled for Monday to determine the cause of death.