A teenager was arrested Sunday on suspicion of killing her mother at a Tokyo condominium in Taito Ward in February.
Investigators suspect the 15-year-old high school student strangled her 41-year-old mother, who was sleeping on a sofa in the living room, between the night of Feb. 26 and the following evening.
The teen was questioned but did not admit to the allegation, the investigators said.
Investigations suggest the teenager's mother was strict, they said. Neighbors at the family's previous residence told the police they often heard her scolding the child in a loud voice.
During questioning before her arrest, the girl complained about her mother making demands about her personal belongings and school choice, the investigators said.
The daughter called for an ambulance on the night of Feb. 27, saying her mother was not breathing. She initially told investigators her mother had been sleeping on the sofa since that morning and felt something was wrong when she didn't wake up by evening.
According to the police, the mother suffocated and was found with a towel wrapped around her bruised neck, indicating strangulation.
Analysis of security camera footage indicated that nobody except the daughter had entered the building around the estimated time of death, they said.
The girl was living in the condo with her parents. The father was away from home due to work on both Feb. 26 and 27, but spoke with his wife over the phone at around 8:40 p.m. on Feb. 26.
On Feb. 27, the girl went to school in the morning and is believed to have returned home around 1:30 p.m., according to the investigators.