Two teenage girls who stabbed their classmate 19 times to please the fictional character Slenderman will be tried as adults, a Wisconsin judge has ruled.

Related: Who is Slenderman?

The girls, Anissa Weier and Morgan Geyser, were charged with attempted first-degree homicide in the May 2014 attack in Waukesha, a suburb of Milwaukee. All three girls were 12 years old at the time.

According to online court records, Waukesha County Circuit Court Judge Michael Bohren ruled that the case will remain in adult court where the girls could be sentenced to up to 60 years in prison if convicted in the stabbing.

Wisconsin law requires cases to begin in adult court if they involve juvenile suspects at least 10 years old who are charged with first-degree attempted intentional homicide.

Attorneys requested hearings in May and June for the judge to consider moving their case to juvenile court. During the hearing for Geyser, her attorney argued that his client would be better served in the juvenile system, where she could get treatment for her mental illness.

Prosecutors say the girls lured a classmate into the woods after a sleepover and stabbed her repeatedly to impress the Internet character Slenderman. She survived the attack and returned to school last fall.