Jury says teen in Slenderman stabbing attack was mentally ill

WAUKESHA, Wisc. -- A Wisconsin jury says one of two teens charged in the 2014 Slenderman stabbing of a classmate was mentally ill when the attack happened.

Last month, Anissa Weier, 15, had pleaded guilty to attempted second-degree homicide due to mental illness or defect in the stabbing as part of a plea agreement. A jury trial on her case, which began Monday, was set to determine whether Weier was mentally ill when she committed the crime.

A total of 10 out of 12 jurors agreed on Friday that Weier had a mental disorder when she and her classmate Morgan Geyser stabbed their sixth-grade classmate 19 times. The girls were allegedly trying to please the fictional internet bogeyman Slenderman.

The girls, who were 12-years-old at the time, were charged with attempted murder and both have been tried as adults.

Waukesha County Circuit Judge Michael Bohren said Weier will be committed to a mental institution. If the jury had found her guilty, she could have gone to prison for 10 years.

"I know her family is relieved. It's hard to say when you are talking about the commitment of a very young child that you are happy but of the options that were there, this is the best and the right one," Weiser's attorney Maura McMahon told reporters following the verdict.

McMahon said Weier will spend at least three years at a mental hospital before petition for her release. A judge could also order up to a 25-year commitment, she said.

"She would have an uphill road," McMahon said.

During the trial, a psychologist testified that Weier developed a condition called shared delusional disorder, in which she came to share Geyser's delusion that Slenderman was real, CNN affiliate WISN reported.

Geyser was diagnosed with schizophrenia a few months after the assault, WISN reported. She also took the prosecutors plea deal and is set to stand trial in October, according to the Wisconsin Court System website.