WATCH: HBO releases trailer for ‘Beware the Slenderman’ documentary

Slender Man Suspects Morgan Geyser and Anissa Weier Photos No graphic Good

NORTHEAST WISCONSIN (WBAY) – HBO has released its trailer for “Beware the Slenderman.”

The documentary is based on the true story of two Waukesha girls who are accused of stabbing their classmate Payton Leutner 19 times at a park in May 2014. According to police, Anissa Weier and Morgan Geyser told officers they tried to kill her in an attempt to please the fictional horror character Slender Man.

All three girls were 12 years old at the time. Leutner survived the attack.

Weier and Geyser have both pleaded not guilty by reason of mental disease to attempted homicide charges in adult court.

The film premiers Jan. 23 on HBO.

The Associated Press contributed to this report.