We now have a first look at an upcoming HBO documentary based on the stabbing of a 12-year-old Waukesha girl.
HBO released the trailer for "Beware the Slenderman" this week.
The documentary covers the case of Morgan Geyser and Anissa Weier, two 12-year-old girls accused of luring Payton Leutner into the woods in May 2014 and stabbing her 19 times.
The girls allegedly told investigators they hoped killing Leutner would please Slenderan, a character they had read about in online horror stories.
Geyser and Weier allegedly held Leutner down and stabbed her multiple times before leaving her to die.
Leutner crawled out of the woods and was found by a bicyclist.
Both girls have pleaded not guilty due to mental disease or defect and are being tried as adults in the case. A trial date has not been set.
The parents of both suspects speak openly about the case in the documentary.
The documentary will premiere on HBO on January 23.