Morgan Geyser and Anissa Weier, both 12, told investigators "Slenderman" made them stab their friend 19 times

On May 31, 2014, Morgan Geyser and Anissa Weier, both 12, lured their friend Payton Leutner into the woods in Wisconsin and stabbed her 19 times, police say.

They later told investigators they had no choice: Kill for “Slenderman” or he would harm them and their families.

Anissa and Morgan were charged as adults with attempted first-degree intentional homicide. Their fascination with Slenderman, a fictional Internet character, and its impact on the girls is the focus of the HBO documentary Beware the Slenderman, which debuts at 10 p.m. ET on Jan. 23.

Anissa’s parents were as shocked as everyone else to learn about their daughter’s obsession with the faceless character, which grew famous online through videos and mostly teen-created fiction.

“It was a picture of this Slenderman character and Jack Skellington,” says Anissa’s father Bill Weier in the documentary. “At the time, it didn’t seem to be anything inherently dangerous.”

Anissa Weir and Morgan Geyer
| Credit: Courtesy Waukesha Police Department
Payton Leutner and rescue workers
| Credit: Abe Van Dyke/AP Photo

For more than two years, everyone has been trying to understand how two girls could plot such a horrific and bizarre crime, in which Payton was left for dead in the park. She miraculously survived after crawling to a nearby bike path and being spotted by a passerby who called 911.


To learn more about the “Slenderman” stabbing case, subscribe now to PEOPLE, or pick up this week’s issue.

The film’s director, Irene Taylor Brodsky, had been working on developing a film for HBO about the human brain in the digital age. As soon as she heard about the attack on Payton, she headed to Wisconsin. In time, Brodsky gained the trust of the girls’ parents.

“In no way is this a whodunit. It’s a whydunit. It’s a howdunit. How could this have happened? And the answers are very complex,” Brodsky says.

| Credit: Courtesy HBO

• Want to keep up with the latest crime coverage? Click here to get breaking crime news, ongoing trial coverage and details of intriguing unsolved cases in the True Crime Newsletter.

“The film goes into the minds of the perpetrators, but I also think it goes into the mind of us as a society,” Brodsky says.

“Slenderman appeals to us for many reasons. The facelessness of him means he can be whatever we need him to be. He’s not just a man that preys on children. Some children see him as a guardian angel. Some kids see him as a protector. These girls, they really believed in his power.”

The girls are expected to go to trial this summer. If found guilty, they each face up to 65 years in prison.

They have both pleaded not guilty by reason of mental disease or defect.