A 57-year-old woman was arrested Monday on suspicion of murdering her mother-in-law in Awara, Fukui Prefecture, in August, police said.
The suspect was identified as Machiko Minami, a native of the town of Harue, Fukui Prefecture. At the time of the slaying, she was married to the 60-year-old son of the victim, Hisae Kondo, 81. Minami has denied killing Kondo.
Police said they suspect Minami bore a grudge against Kondo because she believed her mother-in-law was responsible for her isolation from the rest of the family. They said they will investigate further to establish a clearer motive.
According to police, Minami murdered Kondo in the victim's home sometime between 9:30 p.m. Aug. 20 and 6:40 a.m. the following day by climbing on top of the sleeping victim, covering her mouth and choking her. The cause of death was suffocation caused by pressure to the chest.
Kondo's body was found in the house on the morning of Aug. 21 by another family member. Although a chest in a storeroom next to the bedroom appeared to have been ransacked, police said they suspect it was an attempt by Minami to make it look like a burglar murdered Kondo.
Minami divorced Kondo's son, who runs a company, late last year, they said.