A police official said that Andrei Malanin, 55, was found lying on his back on the bedroom floor, adding that there were no signs of forced entry.
The officer said, “The first signs show a pathological cause of death, but we are investigating nonetheless.”
According to Greek news reports, Malanin’s staff had been looking for him after he failed to report for work in the morning.
The Greek media reported that Malanin lived alone in a Russian embassy-owned building on a heavily-guarded street where the official residences of the Greek prime minister and president are also situated.
Russian authorities confirmed the diplomat’s death.