The mother of a 3-year-old boy who died after being assaulted by her partner in Iwaki, Fukushima Prefecture, had told police around this summer that the partner was violent toward both her and her son, NHK reported.
The boy died after the assault. Police are investigating the case, including how they handled the mother's consultation.
The mother's approach to police came months before the death, putting the response of police and child-welfare services under scrutiny.
Other crime news
Police arrested the mayor of Awa, Tokushima Prefecture, and two others on suspicion of defrauding the city of repair costs for an accident.
Prosecutors sought a prison term of one year and six months for a former Self-Defense Forces member over an intrusion at the Chinese Embassy.
In Chiba, police arrested a dog owner after a Dalmatian bit a woman and seriously injured her.
Satoshi Uematsu, the death-row inmate in the Sagamihara care-home killings, filed a third request for a retrial with the court.
The internal affairs ministry said residents' registry information on domestic violence victims and others leaked in 119 cases over 10 years.