Relatives followed the instructions of a Dutch man who asked not to be disturbed when he went to his bedroom: they left him alone and his body was found in bed four years later, police say.
The man, 50 at the time of his death, lived with four siblings aged between 44 and 71 in the northern village of Minnertsga.
"He was used to being obeyed and very quick to anger," police spokesman Wouter De Vries said.
"Four years ago he told his brothers and sisters he didn't want to be disturbed and went to his bedroom."
Though they frequently passed by the bedroom door, no one dared to open it and look in, Mr de Vries said.
The body was only discovered when the landlords decided some work needed to be done in the room.
"A decomposing body produces a very strong smell, and it's really remarkable that his brothers and sisters don't seem to have noticed anything," the police spokesman said.