Defense: Girl accused of stabbing classmate was delusional

MADISON, Wis. (AP) — A Wisconsin girl who told investigators she helped stab a classmate was convinced the crime would protect her and her family from a fictional horror character called Slender Man, her attorney told jurors today.

The defense is trying to convince jurors 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.

Payton Leutner was stabbed 19 times in a plot by Weier and co-defendant Morgan Geyser, prosecutors said, and left in a wooded park where she eventually crawled for help after the girls left. A passing bicyclist found Leutner. Weier and Geyser were arrested later that day while walking to meet Slender Man in a northern Wisconsin forest. All three girls were 12 years old at the time.

"Anissa's broken mind caused her to lose touch with reality," attorney Joseph Smith told jurors. "Anissa was under the command and control of a delusional disorder."

Waukesha County Assistant District Attorney Kevin Osborne told jurors during opening statements Weier and Geyser knew they were committing a crime. Osborne says the initial plan was for Weier to stab Leutner, but Weier couldn't do it and instead commanded Geyser to do the stabbing.

"They knew this was wrong. They understood what they were doing was wrong," Osborne said.

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 because she lacks the capacity to understand her conduct was wrong.