A 71-year-old woman in central Japan suspected of murdering her husband has told investigators she strangled her in-laws as well, local police said Monday, pointing to the stress of being the sole caregiver in the family as a possible motive.

Masako Kishimoto was arrested Sunday for allegedly choking her husband Takio, 70, to death with a towel while he was asleep at their home in the city of Tsuruga, Fukui Prefecture, in the early hours that day.

The bodies of Takio's father Yoshio, 93, and mother Shinobu, 95, were also discovered.