Updated

The lawyers for a Wisconsin girl accused of trying to kill a classmate to please a fictional horror character called Slender Man are challenging her confession.

Fifteen-year-old Anissa Weier (ah-NEE'-sah WY'-ur) and 14-year-old Morgan Geyser have pleaded not guilty by reason of mental disease to attempted homicide charges in adult court. Both girls were 12 when prosecutors say they stabbed classmate Payton Leutner (PAY'-tun LYT'-nur) 19 times in a Waukesha park in 2014.

Weier's lawyers say she was too young to understand her Miranda rights to remain silent and to have an attorney present.

During the hearing Thursday, William Weier testified he never discussed Miranda rights with his daughter. Anthony Jurek, a forensic psychologist, testified Weier didn't have an adequate understanding of Miranda rights.

A judge will rule in February.