KOBE -- Police and lawyers for the 15-year-old boy being held for the slayings of Jun Hase and Ayaka Yamashita, as well as for violent assaults on other children in Kobe, came to the conclusion July 21 that the teen-ager may be insane.

The family court will be asked to conduct psychiatric tests, say sources close to defense lawyers. Under the Juvenile Law, a minor can serve up to a three-year sentence in a juvenile detention facility, but in cases of insanity would be sent to a mental hospital.

A dated notebook seized from his home has dated entries written by the suspect about the brutal March attacks on children here. The attacks are desribed as "holy experiments" to confirm the fragility of humans. There are also letters in the journal that appear to address a god he named "Bamoidoki-shin."

The suspect was served a second warrant last July 15 on suspicion of assaulting in February and March four schoolgirls, one of which was attacked March 16 with a hammer. Ayaka Yamashita, 10, died of her injuries March 23.

The suspect, a student at Tomogaoka Junior High School, was arrested June 28 on suspicion of killing and decapitating Hase, 11, whose head was found May 27 placed in front of the school's front gate. He has reportedly confessed to the crimes.

When he was first arrested, it was suspected that he had a grudge against Japan's compulsory education system and that he used this grudge as motivation for murder. But police say his testimony has shown that his mental condition is probably what drove him to brutality.