One of two 12-year-old Wisconsin girls charged as an adult with stabbing a classmate to please a fictional online horror character "Slender Man" is mentally incompetent and can't stand trial, a judge said Friday.

The judge also ordered that she be committed for treatment, and said attorneys have a year to restore her to competency. He acted after receiving reports from two doctors and hearing from attorneys.



The girl's attorney previously said he believed she was mentally ill and a primary goal would be to have her case moved from adult to juvenile court, where more mental health and other services might be available. Wisconsin law requires anyone age 10 or older to be charged as adults in severe crimes.



NBC News is not naming the girls due to their ages and attorneys' hopes to have the cases moved.



According to court documents, the girls plotted for months to kill their friend to curry favor with Slender Man, a character in horror stories they read online.



They told investigators they believed Slender Man had a mansion in a Wisconsin forest and they planned to go live with him after the slaying.



One of the girls hosted the other two at a May 30 slumber party to celebrate her birthday. The next morning, the two girls attacked the victim in a wooded Waukesha park. One told investigators that she told the victim to lie down and be quiet after the stabbing so that she would lose blood more slowly.



The girl said she hoped to convince the victim to be quiet so the victim would not draw attention to them and would die.



Once the attackers left, the 12-year-old victim crawled from the woods to a road where a passing bicyclist found her. Doctors later told police the girl had narrowly escaped death because the knife missed a major artery near her heart by just one millimeter.



Police have not identified her, and her parents asked friends to keep her name secret.