 Satō's mother lived downstairs and apparently had no contact with her son's captive since he became very violent whenever she tried to go upstairs.However, police believe the mother must have had some knowledge of Sano's presence; for example, it was alleged that she purchased feminine hygiene products for the victim.The mother of Nobuyuki Satō, then 73 years old, consulted the Kashiwazaki public health center in January 1996, because her son had been acting strangely and was violent to her.