Mother of 12-year-old victim in Slenderman case speaks out

WAUKESHA (AP) — A 12-year-old girl who was stabbed 19 times by classmates trying to please a fictional horror character had spoken to her mother about the specter called Slenderman before the attack.

The girl was attacked in a wooded park in late May following a sleepover to celebrate her best friend's birthday. Police say that girl and another 12-year-old classmate later told investigators they spent months planning the attack intended to win favor with Slenderman.

The victim's mother told ABC's "20/20" that her daughter had asked about Slenderman before the attack because she was scared by stories sent by her friend. The victim told her mother her best friend knew Slenderman was real.

The victim's mother says she thought it was just a child's fantasy that the girl's friend would outgrow.