An 11-year-old girl will face a juvenile trial at a family court in southern Japan on charges of killing her classmate with a box-cutter (search), authorities announced Tuesday.

Court officials decided to put her on trial after reviewing the case, a Nagasaki prefecture Family Court spokesman said. Under Japanese law, she will not be tried for criminal responsibility because she is under 14.

The sixth-grader has been in juvenile detention since last week, when she allegedly led 12-year-old Satomi Mitarai to an empty classroom during their lunch hour, slit her neck and arms with a box-cutter, and left her to bleed to death.

Investigators believe the two had exchanged nasty messages over the Internet.

The court sessions will be closed and the girl's name will not be released because she is a juvenile. The panel of three judges could decide to place her in a juvenile correctional facility (search). It was unclear how long she might have to stay.

Kyodo News agency said court proceedings would be completed by June 29, unless psychological tests are ordered.

The decision came on the third anniversary of a killing that shocked Japan, when a man entered the grounds of an elementary school and stabbed eight children to death.

Memorials of that rampage and a letter written by Satomi's devastated father dominated news reports Tuesday.

"The belief that a school is, and must be, the safest place (for children) is crumbling," Education Minister Takeo Kawamura told reporters. "More has to be done to prevent these incidents."

The letter written by Kyoji Mitarai, 54, expressing his loss and confusion since his daughter's June 1 killing, was published on the front pages of national newspapers.

"Why aren't you here? That's what I can't understand," he wrote, reminiscing about how his daughter had been the one to cheer him up after her mother died from illness three years ago.

"Where are you? Have you seen your mother yet? Where are you playing now?" said the letter.

The homeroom teacher who found Satomi has since been hospitalized for trauma, and children at Okubo Elementary School, in Sasebo, 650 miles southwest of Tokyo, are undergoing counseling.

Increased juvenile crime and violence at schools in recent years has eroded Japan's image as a safe haven.

Last July, a 12-year-old boy in Nagasaki — a city just north of Sasebo — was accused of kidnapping, molesting and murdering a 4-year-old by shoving him off a roof. In 1997, a 14-year-old beheaded an 11-year-old neighbor.

Police statistics show that while violent crime, like murder and robbery, among children under age 14 is still low, it is on the rise.