An expert witness has testified about a history of mental illness in the family of one of two Wisconsin girls charged with trying to kill a classmate to please a fictitious horror character.

Forensic psychologist Deborah Collins testified for the defense Wednesday at a hearing for the 13-year-old girl. The girl's attorney wants the case moved to the juvenile system, arguing she can get better care there.

Collins testified the early onset schizophrenia diagnosed in the girl may have a genetic basis. Collins said the girl's father suffered from a similar mental illness as an adolescent.

The two girls are accused of stabbing classmate Payton Leutner 19 times to gain favor with Slender Man, a character they believed could kill them. Leutner survived the 2014 attack at a Waukesha park.