The partially mummified corpse of a 64-year-old woman was found in a rental home in Sapporo, police said Thursday, adding they questioned her older sister and brother who shared the dwelling and got inconsistent responses.

The dead woman, whose identity has not been released, was found lying on a futon Thursday at the home, the police said. The body bore no external injuries and thus it is possible the woman died of natural causes, they said, adding, however, that her siblings, both in their 70s, never reported the death to authorities.

The police may establish a criminal case against the siblings because of the inconsistencies in their responses to questioning.

A source said the three siblings rented the house together, and the dead woman paid the rent to their landlord every month. But she hurt her legs last fall and became unable to walk, and asked the landlord to visit the house to collect the rent instead.

Last month the woman became unreachable.

The home is located about 10 km south of JR Sapporo Station.