Japanese girl accused of beheading friend has history of violence

Schoolteachers and other associates of a Japanese schoolgirl accused of the "dissection" murder of a classmate are engaged in soul-searching over whether they should have heeded warning signs of the alleged killer's deteriorating mental state.

The 16-year-old, who was arrested on Sunday for the decapitation of 15-year-old friend Aiwa Matsuo, was raised in a wealthy family in Sasebo, a port city of 255,000 people.

She was close to her mother, got good grades and was a good athlete at school. One childhood friend said that she "had a sense of responsibility and was caring".

But there were warning signs. City officials said that when she was in her sixth year of primary school, she laced the lunches of two classmates with diluted bleach and detergent on five occasions. A source close to one of the victims said the girl had been angry with remarks about her studies.

The girl's mother apologised at the time, promising to discipline her. She received counselling and the school reported the problem to the municipal government, according to sources. But a member of the city's education board said he believed no official report was made.

A former teacher at the primary school said the city, school and the parents might not have taken the right action.

"We just sought a closure of the problem without seriously facing the dark side of her mind," the teacher said. "I feel sorry because we could've prevented the incident if we had acted in the right way."