Police investigating Monday's fatal attack on a family in Notsu, Oita Prefecture, found a severed telephone line in the family home, it was revealed Tuesday.
Investigators believe the suspect, a 15-year-old neighbor boy, may have severed the line in an attempt to delay someone from reporting the incident, in which three members of the Kazumasa Iwasaki family were fatally stabbed and three others seriously injured.
They said, however, they could not rule out the possibility that the line was accidentally ripped out during the killing spree, as it appears to have been severed by hand.
Iwasaki's granddaughter, Mai, 16, who suffered serious injuries to the back, called police with a cellular phone, police said.
The boy was expected to be sent to a local prosecutors' office Tuesday afternoon.
Meanwhile, the high school attended both by the boy and the granddaughter held an emergency general assembly Tuesday. It aimed to explain details of the incident to students on summer vacation.
In front of more than 300 students, the school principal spoke to students about the preciousness of life. He also urged students faced with problems to consult with teachers.
School sources and investigators said that the boy did not fit in well at school. They said he quit the baseball team soon after joining in April and was beaten up by classmates in May.