Police said that judging by the post that had been delivered to the apartment, the food in the fridge and the man's diary, he appeared to have died three years ago.
“Police were called to the apartment because the neighbours hadn't seen the man in a very long time, and they had contacted the landlord,” Södermalm police officer Viktor Adolphson, who also tweeted about the incident, told The Local.
“There was a lot of post by the door, and judging by the post and other factors it appeared that the man had been dead for more than three years.”
Inside the apartment, a light had been left on and the radio was also still playing.
Adolphson described the man as “elderly” and said police were working from the assumption that the death was of natural causes, but that the cause of death would be confirmed by a forensics team.
He said that it was rare for a deceased person to go so long without their death being discovered.
“Most often, someone notices if there's a friend or someone had booked an appointment with the person, they'll notice that the person isn't there. But it happens, unfortunately,” the police officer said.