A 16-year-old girl who murdered and dismembered a classmate in Sasebo, Nagasaki Prefecture, last July, will be sent to a medical reformatory rather than be tried in a criminal court.

The Nagasaki District Court handed down its ruling on Monday. The presiding judge said the girl, who suffers from an autistic disorder, lacks any sense of morality and that sending her to prison would worsen her mental condition and make rehabilitation more difficult, Sankei Shimbun reported.

The girl was judged to be criminally responsible after a series of psychiatric tests last autumn.

Prosecutors said that because the girl had researched laws surrounding juvenile crimes at the library, and because she had purchased a weapon before the incident, she had meticulously planned the attack and was therefore criminally responsible for the murder of her classmate.

The girl was arrested on suspicion of murdering fellow student Aiwa Matsuo, 15, after police discovered her dismembered body on a bed in the suspect's home in Sasebo on July 26 last year. The teenager confessed to decapitating Matsuo and cutting off her hand, reportedly telling investigators she "wanted to dissect" someone.

The suspect's father was found dead in an apparent suicide on Oct 5 after it was revealed by media that the girl had assaulted him with a baseball bat in March.

After his daughter's arrest, the 53-year-old man released a statement to the media, saying her act "can never be forgiven for any reason or cause."

In the statement, he said the killing deprived the victim of "time to experience the joy and happiness of life. When I think of the shock and sorrow felt by the bereaved family, it breaks my heart. I can't find the words for an apology."

Prosecutors said the girl showed signs of stress after her father's death, but has not shown any remorse for killing her classmate.

The suspect had been living alone in the apartment, where the murder occurred, since April. Her mother died of cancer in 2013 and her father had remarried in January 2014.

© Japan Today