Yu Hagino, a part-time cram school teacher arrested in the fatal stabbing of a 12-year-old girl at the school in Uji, Kyoto Prefecture, phoned his father shortly after the slaying to inform him of his crime, police sources alleged Monday.

Police sources said earlier that the 23-year-old Doshisha University law student had called only police after the slaying, which took place Saturday at the Ujishinmei branch of the Kyoshin cram school chain.

The victim, sixth-grader Sayano Horimoto, died after being stabbed in the neck and face, a police autopsy showed. Police earlier quoted Hagino as telling investigators he did not get along with the girl and lost his temper after she allegedly told him to go away.

On Dec. 2, Hagino bought two kitchen knives at a hardware store and later, a hammer, which suggests the murder may have been premeditated, the police sources said.