The attorney for one of two Wisconsin girls accused of trying to kill a classmate to please a fictional horror character called Slender Man is challenging prosecutors' use of his client's confession.

In a motion filed in Waukesha County Circuit Court, the attorney for Morgan Geyser argues she was too young and had not been treated for schizophrenia when she talked to investigators on camera about the stabbing of classmate Payton Leutner in 2014. Payton, Morgan and Anissa Weier were all 12 at the time.

Morgan and Anissa have both pleaded not guilty by reason of mental disease to attempted homicide charges in adult court. Payton was stabbed 19 times in a Waukesha park, but crawled out of some woods where she was found by a bicyclist.