MADISON, Wis. (AP) - A Wisconsin teenager accused of stabbing a classmate in order to please a fictional horror character known as Slender Man goes on trial Tuesday, with a jury to decide whether she was mentally competent at the time.
Anissa Weier and a co-defendant, Morgan Geyser, were just 12 at the time of the attack at a park in suburban Milwaukee in 2014. The third girl, also 12, survived her wounds.
Twelve jurors and four alternates were chosen Monday, and opening statements were scheduled Tuesday. Weier, now 15, has admitted a role in the stabbing but pleaded not guilty due to mental illness.
A plea agreement calls for her to be committed to a mental hospital for at least three years if she's judged to have been mentally ill; if not, she faces 10 years or more in prison.
Prosecutors allege that Weier and Geyser lured Payton Leutner into a Waukesha park in May 2014 and stabbed her 19 times. The girls have said it was an effort to please Slender Man and become his servants, or to keep the character from attacking their families.
A passing bicyclist found Leutner, and Weier and Geyser were captured later that day.
Prosecutors charged both girls with being a party to attempted first-degree intentional homicide. Weier struck a deal with prosecutors in August in which she pleaded guilty to being a party to attempted second-degree intentional homicide, essentially acknowledging she committed all the elements of the offense. But she also has pleaded not guilty due to mental illness, meaning she believes she isn't responsible for her actions.
Weier told a judge during her plea hearing in August that she believed Slender Man would attack her and her family if she didn't kill Leutner. Psychologists have testified that she suffered from persistent depression and a delusional disorder linked to schizotypy, a diminished ability to separate reality from fantasy.
At least 10 of the 12 jurors must agree on a verdict.
Geyser has pleaded not guilty to being a party to first-degree attempted homicide. Her trial is set to begin Oct. 9.