One of two preteen girls accused of stabbing a classmate to please the fictional horror character Slender Man is due back in court.

A judge in Waukesha is expected to get an update Wednesday on the girl's mental state after he ordered her in August to receive mental health treatment.

A psychologist testified then that the girl claims to see and hear things that others cannot — including unicorns, Slender Man and Voldemort, an antagonist in the Harry Potter series.

Court documents say the girl plotted with one friend to kill another to please Slender Man. The two girls attacked the victim in a wooded Waukesha park after a May 30 sleepover, stabbing her 19 times. The victim survived by crawling to a path where a bicyclist found her.