The defense is trying to convince jurors that Anissa Weier was suffering from a mental illness at the time of the stabbing at a Waukesha park in 2014 and therefore is not criminally responsible.
Anissa Weier egged on friend Morgan Geyser as she attacked Payton Leutner so the pair could avoid the wrath of supernatural character Slenderman.
Van Rybroek said that shared delusional disorder left her unable to control her actions.
Weier and Geyser were both 12 years old when they lured their classmate, Leutner, into the woods in the Milwaukee suburb of Waukesha and allegedly stabbed her. "I know her family is relieved".
Jurors asked to see Weier's police interrogation video from 2014.
McMahon guaranteed Weier was desolate and discouraged coming from her parent's separation, and she hooked onto Geyser. McMahon also said that a judge can order up to a 25-year commitment for Weier.
Slender Man first appeared on the internet in 2009. Although Weier did not physically stab Leutner, in her mind she knew it had to be done, Smith told jurors.
"The potential release of an assailant that methodically planned and executed an attack in which our little girl was stabbed 19 times puts the community and our family at risk", the statement continued. Van Rybroek is the second court-appointed expert to evaluate Weier's insanity plea.
Weier, now 15, pleaded guilty to attempted second-degree homicide in August and is now on trial over whether she should be held criminally responsible or committed to a psychiatric hospital.
Westendorf admitted under cross-examination that the condition is rare among two children who are friends. Weier and Geyer felt like they had to kill classmate Leutner. "If adults have trouble distinguishing fake news, 12-year-olds will, because their brains can't yet discern or analyze as well". The stabbing victim, who Reuters has not named, survived the attack.
Her trial is set to start in October.
Weier told authorities that she and Geyser believed they had to kill Leutner or else Slender Man would kill them and their families.
Both Weier and Geyser were originally charged with attempted first-degree intentional homicide.
Maura McMahon, Weier's attorney, said she trusted the case uncovered that kids might be taking care of mental issues lost on grown-ups who have turned out to be excessively occupied with their own particular lives, making it impossible to focus and assets proliferate to help them.
But she also pleaded not guilty due to mental illness of defect, setting up the trial on her mental status.