A woman from Shichigahama, Miyagi Prefecture, has been arrested for allegedly discarding the bodies of her mother and brother, police said.

Sachie Sato, 55, the second daughter of Kano Sato, is alleged to have buried the body of her 87-year-old mother sometime between July 27 and Oct. 20 at the family residence.

Sachie Sato was arrested in Odate, Akita Prefecture, at around 1 p.m. Monday.

According to investigators, Sachie Sato lived with the two victims and cared for the mother, who was ill. She disappeared on Oct. 20, the day Kano Sachie's body was found buried in the yard of the family home.

When municipal officials in charge of the mother's nursing care insurance visited the house that day, they found a letter written by Sachie Sato saying: "I'll leave home with my mother. Thank you."

Police officers who were called to the house by the municipal officials found evidence that the yard had been disturbed. They started digging and found the elderly woman's corpse.

The body of Sachie Sato's 57-year-old brother, Choichi, was found under the floor of the house two days later.

Their older sister said Sachie Sato had been exhausted from taking care of their bedridden mother.

"She looked tired from nursing (her) mother and seemed to be financially struggling," the elder sister said. "She was also complaining of sleep deprivation as the mother would get out of control in the middle of the night."

Kano Sato appeared to have been dead for between several weeks and several months, investigators said, adding they have not yet determine the cause of her death. Choichi Sato had had sustained multiple wounds to the back of his head and had apparently been dead for several months to a year, the investigators said.