The father of a boy slain in Akita Prefecture said Thursday he has filed a complaint with the prefectural safety commission alleging that sloppy police work led to the murder.

Katsuhiro Yoneyama, 40, is demanding an apology from the police and is urging the commission to examine the way they investigated the murder of Ayaka Hatakeyama, 9, in April. Hatakeyama was allegedly murdered by her mother, who is also suspected of murdering Yoneyama's 7-year-old son, Goken, the following month.

According to the complaint, filed with the Akita Prefectural Public Safety Commission, Yoneyama said the investigations into the murder of the girl were insufficient, a conclusion drawn from his own research, in which he questioned 242 households.

"Because of improper investigations, my son was also murdered," Yoneyama says in the complaint.