10 Years After Slender Man Stabbing: Why Did a Pair of 6th Graders Try to Kill Their Classmate?

May 31, 2024, marks 10 years since two 12-year-old girls — Morgan Geyser and Anissa Weier — attacked and tried to kill their friend after growing obsessed with Slender Man, an online supernatural character.

Weier and Geyser were both found guilty of attempted homicide and sentenced to serve time in a mental institution, TMJ-4 reports. In 2021, Weier was granted conditional release from Winnebago Mental Health Institute in Oshkosh, Wis.. Geyser's April 2024 request to be released was denied, per the Associated Press.

Read PEOPLE's January 2017 print story about the case below.

It began with a slumber party to celebrate Morgan Geyser’s 12th birthday. Then Morgan and her friends Anissa Weier, 12, and Payton Leutner, 12, spent the morning of May 31, 2014, eating strawberries and donuts before heading out to a park near Morgan’s Waukesha, Wis., home. But the hours that followed played out like a terrifying horror film. By that afternoon Anissa and Morgan were sitting in separate police interrogation rooms, explaining how they’d stabbed Payton 19 times and left her for dead in the woods. “Morgan handed me the knife,” Anissa told Waukesha police authorities in a taped interview. “I give it back to her and say, ‘You do it. Go ballistic. Go crazy.’”

In another room Morgan told detectives how it felt to stab Payton, a friend she’d known since fourth grade. “I didn’t know what I did. It just sorta happened,” she said. “It didn’t feel like anything. It was like air.” Although Payton miraculously survived — crawling through dense woods to a nearby bike path where a passerby called 911 — the crime shocked authorities, especially after police discovered the girls’ apparent motive: to win favor with the fictional Internet horror character Slenderman.

In 2017, the bizarre case was the subject of an HBO documentary, Beware the Slenderman, that attempted to decipher how two seemingly normal tween girls could do something so horrific. “Of course they’re guilty, but how much do we hold them accountable?” asks director Irene Taylor Brodsky, who points to the girls’ ages and questions the impact the Internet has on the developing brains of tweens. “It really could be any of our kids.”

Chillingly, Anissa and Morgan do seem to have been typical 12-year-olds. “[Anissa] was in a Girl Scout troop in elementary school,” Anissa’s father, Bill Weier, who appears in the documentary, tells PEOPLE. “She liked animals. She liked roller-skating.” Anissa and Morgan lived in the same condominium complex and rode the same bus to school. Their bond grew tighter as the months passed and they developed an obsession for Slenderman, who, they later told police, would harm them or their families if they didn’t kill in his name.

Although Morgan, according to her parents, has been diagnosed with early-onset schizophrenia, Anissa has no history of mental illness. “Anissa had some issues making friends and all she wanted was friends,” says psychologist Dr. Abigail Baird. “And she happened to make friends with someone who maybe wasn’t the most grounded in reality.”

Payton, who was stabbed in the liver, stomach and heart, went on to high school and declined, along with her parents, to participate in the documentary. But Anissa’s father said they are all constantly in his thoughts. “I think about them every day of my life,” Bill Weier said. “As much as I would like to be able to talk to them about this, number one, how do you start that conversation? And number two, would it even be right?”

Meanwhile, Anissa, now 15, and Morgan, now 14, are in different facilities awaiting trial on attempted first-degree intentional homicide charges later this year. They are not allowed contact with each other or access to the Internet, according to a court order. At the time of their arrest Anissa told police she was conflicted about trying to kill Payton. “The bad part of me wanted her to die,” she said. “But the good part of me wanted her to live.” Morgan, she says, convinced her that the attack would prompt Slenderman to take them to his mansion in a neighboring forest. “Morgan said, ‘Slender, if you’re listening, please help us,’” Anissa recounted. “And he didn’t do anything. Nothing happened.”