One of the teens criminally charged with stabbing a classmate in 2014 to please the fictional character Slender Man will be sent to a mental institution instead of prison.

Late Friday night, a Wisconsin jury found that Anissa Weier (pictured left), now 15, was mentally ill at the time of the attack, CNN reports.

Weier last month had pleaded guilty to attempted second-degree homicide as a party to a crime with use of a deadly weapon.

Because of the plea, jurors on Friday were examining only whether she was legally responsible because of mental illness.

Of the 12 jurors, 10 of them agreed that the teen was suffering from a mental disorder when she and fellow classmate Morgan Geyser (pictured right) stabbed the victim 19 times in a wooded area.

The victim was able to crawl out of the woods and was found by a passerby.

Weier told authorities she believed Slender Man would harm herself and her family if she didn’t stab the victim.

“I believed that if I didn’t go through with it, Slender Man would come and attack and kill myself, my friends and my family,” she told the court last month. “Those I cared about the most.”

Prosecutors later charged Weier and Geyser, who were 12 years old at the time of the crime, as adults instead of juveniles.

Weier will be committed to a state mental hospital. As part of the plea deal, she has agreed not to seek release from the institution for at least three years, but she could remain in the facility for up to 25 years.

If the jury had not found Weier mentally ill, she could have been sentenced to prison for a decade, according to one of her lawyers, Maura McMahon.

“I know her family is relieved,” McMahon told reporters after the verdict. “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.”

A psychologist testified during the trial, which started Monday, that Weier was suffering from shared delusional disorder. That caused her to share in Geyser’s belief that Slender Man was real.

For her part, Geyser has been diagnosed with schizophrenia. She also has accepted a peal deal and is scheduled to stand trial next month.