Morgan Geyser agrees to plea deal.
One of two participants in the Slender Man stabbing has decided to plead guilty and will not go to trial.
Morgan Geyser, 15, appeared in court Friday with her attorney and informed the judge that she will plead guilty to attempted first-degree intentional homicide.
But while Geyser pleaded guilty to the crime itself, the deal stipulates that Geyser is not guilty by reason of mental illness.
A plea hearing has been scheduled for next week.
Prosecutors allege Geyser and her friend Anissa Weier lured classmate Peyton Leutner into a Waukesha Park and stabbed her 19 times in May, 2014.
According to law enforcement, the girls later told investigators they carried out the stabbing in an effort to become proxies of the online, horror character Slender Man.
Geyser and Weier, as well as the victim, were all just 12 years old at the time.
Following the stabbing, Geyser and Weier are accused of wandering north in an effort to reach the Slender Man's mythical mansion, which they believed was in the Nicolet National Forest.
The girls were both charged with attempted first degree intentional homicide.
In Wisconsin, anyone 10 years of age or older charged with attempted first or second degree intentional homicide is considered an adult.
Geyser pleaded not guilty, while Weier pleaded guilty to a lesser charge and earlier this month was found not legally responsible for the crime by a Waukesha County jury.
Weier is expected to be sentenced later this year and faces at least three years in a mental hospital.
Geyser's plea deal calls for a maximum of 40 years in a mental institution. There's no minimum sentence.