This Internet is abuzz with speculation about a bizarre attempted murder in which two 12-year-old girls stabbed their classmate as an offering to “Slender Man”—a supernatural entity created for the website Something Awful in 2009. The story has made international news. But how did an Internet meme manifest into actual violence?

Criminologists and psychologists, as well as Christian demonologists and a retired FBI agent have all weighed in. The genesis of the crime appears not to lie with media or an inability on the part of the perpetrators to distinguish fantasy from reality, but rather a kind of “corrupted play” that resulted in irrevocable consequences. The Slender Man phenomenon, which had intrigued academics even before this incident, is relevant for folklorists and religion scholars who study the relationship between supernatural ideas and social action.

Slender Man was born on June 10, 2009, when Eric Kundsen entered an Internet contest to create doctored photos portraying supernatural entities. His images of a faceless being in a suit with elongated limbs inspired numerous stories, games, and videos that appeared on websites like Creepypasta. In an NPR interview Knudsen explained that he feels more like the creature’s manager than its creator.

Soon online forums speculated that Slender Man had not been created by Knudsen, but was a real entity described by ancient cultures around the world. A recent book by Rev. Robin Swope (aka “The Paranormal Pastor”) asserts that Slender Man is an actual demonic entity rather than an Internet meme. The body of material surrounding the history, abilities, and motivations of Slender Man now comprises what folklorists call a “legend complex.”

Morgan Geyser and Anissa Weier of Waukesha, Wisconsin, were fascinated with Slender Man and harbored a dark fantasy of contacting the entity through an act of human sacrifice. On May 30, Geyser celebrated her birthday with a trip to the skating rink followed by a slumber party. She invited two friends: Weier and the victim. The following morning they lured the victim into the woods where Geyser stabbed her 19 times. The victim managed to crawl to the road where a cyclist rendered aid. The perpetrators told police that they hoped the murder would summon Slender Man who would take them to live in his mansion located in nearby woods.

Police blamed “unmonitored Internet usage” for the attack and the local school district banned access to “Creepypasta.” A statement on Creepypasta denies culpability, explaining, “There is a line of between fiction and reality, and it is up to you to realize where the line is. We are a literature site, not a crazy satanic cult.”

While experts are divided, the raw power of Internet memes is not a cogent explanation. Sociologist Sherry Turkle was quoted as saying that the Internet has dangerously blurred the lines between games and reality, especially for young people. However, Jacqueline Woolley, a psychologist who researches children’s ability to distinguish reality from make-believe, suggests that 12-year-olds have the same grasp on reality as adults. Kenneth Lanning, a retired FBI agent who investigated rumors of Satanic Ritual Abuse in 1992, explained that media is not the key factor and that the attack may have occurred in a moment of limited inhibition.

An attorney for one of the girls has argued that his client is mentally ill and is seeking a mental evaluation. However, vague diagnoses of “mental illness” are more often tautologies than an explanation of tragic events: i.e. “She exhibited deviant behavior because she was mentally ill and we know she was mentally ill because she exhibited deviant behavior.” This sort of lazy analysis stigmatizes those being treated for mental health and often obscures more tangible factors.

Another possibility is that the girls’ confession about the Slender Man mythos was an “atrocity story” intended to gain clemency. Accused criminals sometimes spin stories in which they were manipulated or coerced by cults or Satanists. Police interrogators often encourage such stories. Geyser seemed to engage in this tactic somewhat, telling police that if she hadn’t carried out the attack, “he” would kill her family. She then asked if a stabbing could be considered an act of self-defense. However, this interpretation still doesn’t explain the motivation for the attack.

Robert Kinscherff of the National Center for Mental Health and Juvenile Justice argued that it was the intensity of the girls’ relationship, rather than mental illness, that led to the attack. He explained, “It’s about loyalty and constructing a world where this makes sense.” Similarly, criminologist Jack Levin opined, “I think it’s the chemistry between these two girls. It was insane. Not in their minds but in their relationship.”

I submit that Geyser and Weier were engaged in a form of play that extended the Slender Man legend complex through performance. Then, in a moment of lowered inhibitions, irrevocable consequences occurred, making the play world real. In 1983, folklorists Linda Degh and Andrew Vazonyi described how legends are transmitted through ostension, in which physical actions and performances rather than words or media, affirm the legend. In this way, facts can be turned into narratives and narratives can be turned into facts. Ostension can include pranks, such as the envelopes full of Bisquick that were mailed following the 2001 anthrax scare, or—in extreme cases—to copycat crimes.

The girls’ fascination with Slender Man was performative. Anna Freud noted that children often pretend to be monsters, acting out the very thing that they fear. Sometime between December 2013 and January 2014, Geyser came upon the idea of becoming “proxies” for Slender Man—that is, living extensions of the legend complex. The game of becoming “proxies” was a form of ostension, proving the legend is real. One girl explained, “Many people do not believe Slender Man is real. [We] wanted to prove the skeptics wrong.”

Ikuya Sato argued that senseless youth crimes often occur through a sort of play in which players attempt to “reach the limit” of their assumed roles, resulting in irrevocable consequences. Sato’s model of “corrupted play” fits several cases of youth crime with occult elements but no apparent motive. The plot to sacrifice a child seemed to unfold as a game that neither player wanted to curtail. Weier packed items she would need for her new life in Slender Man’s mansion, including photos of her family. Their original plan to kill the victim in her sleep was repeatedly aborted and rescheduled. Prior to the attack the knife was passed back and forth, as both girls were reluctant to go through with it. The girls only succeeded in the attack by sharing agency—with Geyser wielding the knife and Weier giving the order to “Go ballistic.” In this way, both girls could feel they were not making a conscious decision.

The disturbing conclusion from this episode is that this attack was probably not the simple result of dangerous media or “mental illness.” Instead, behaviors that are relatively normal—fascination with horror, adolescent performance of legends, creating make-believe worlds—produced a perfect storm that resulted in tragedy. The conclusion of Degh and Vazsonyi’s 1983 paper on ostension now seems eerily prescient: