A Wisconsin girl who admitted to participating in the stabbing of a classmate to please horror character Slender Man will avoid prison after a jury determined Friday that she was mentally ill at the time of the attack.
Anissa Weier and Morgan Geyser lured classmate Payton Leutner into the woods at a park in Waukesha, a Milwaukee suburb, in 2014. Geyser stabbed Leutner 19 times while Weier urged her on, according to investigators. A passing bicyclist found Leutner, who barely survived her wounds. All three girls were 12 at the time.
The decision means Weier will be sent to a mental hospital rather than prison. A plea agreement calls for her to spend at least three years at a hospital.
► Make it easy to keep up to date with more stories like this. Download the WFMY News 2 App now.
Three psychologists testified that she suffered a shared delusion that she and Geyser had to kill Leutner to become Slender Man's servants and prevent the character from killing their families.
Both Weier and Geyser told detectives they felt they had to kill Leutner to become Slender Man's "proxies," or servants, and protect their families from the demon's wrath.
Weier, now 15, pleaded guilty to attempted second-degree intentional homicide in a deal with prosecutors in August. But she has claimed she was mentally ill during the attack and not responsible for her actions.
The jury began deliberations Friday morning. CBS affiliate WDJT reports that the judge in the case told the 12 jurors that only 10 need to agree on a verdict, although he would prefer them to be unanimous.
Weier's attorney, Maura McMahon, said during closing arguments that Weier was lonely and depressed after her parents divorced and she latched onto Geyser.
Together they became obsessed with Slender Man, developing a condition called shared delusional disorder, McMahon said. Weier believed Slender Man could read her mind as well as teleport and would kill her or her family if she talked about him, she said.
Geyser has pleaded not guilty by reason of mental disease to being a party to first-degree attempted intentional homicide. Her trial is starts Oct. 9.
© 2017 CBS Interactive Inc. All Rights Reserved.