A 13-year-old girl in Ohio allegedly put on a white mask yesterday, waited in the kitchen for her mother to get home, and attacked her with a knife. The girl supposedly has no memory of the incident; she was taken to a juvenile detention center while her mother was treated for wounds in her neck and back. "It didn't feel like her at all," the mother told a local TV station.

The above story reads like one of the apocryphal tales of Slenderman, a spindly, evil creature invented on the Something Awful forum in 2009 and perpetuated in online amateur fiction, drawings, video games, and YouTube videos. The stories are often reported as if they were real. Sadly, this one was.

Though he’s yet to kill, Slenderman has now claimed at least two victims. The girl in Ohio who attacked her mother was reportedly obsessed with the character, as were two seemingly normal 12-year-old girls who stabbed a classmate 19 times last week and left her to die in the woods.

The girls claimed they wanted to kill their classmate in order to get an invitation to Slenderman’s mansion. "Many people do not believe Slenderman is real [and we] wanted to prove the skeptics wrong," one told police.

Slenderman is one of the most popular characters to come out of "creepypasta," the internet-native horror literature and associated community of fans and contributors. Creepypasta grew out of "copypasta," chain emails that asked readers to copy and paste the text and pass it on.

Slenderman was first depicted as a blurry figure Photoshopped into the background of a picture of some children. He has been known to kidnap kids as well as force people to attack each other and themselves.

It’s not unusual for murderers and criminals to cite pop culture as an influence. Rage, a story about school shooting written by Stephen King under a pseudonym, inspired multiple school shooters. Alabama teen Devin Moore claimed months of playing Grand Theft Auto caused him to kill three men. Cult leader and convicted murderer Charles Manson believed The Beatles’ lyrics were about murder and race war.

"The question of media influence on murder is a very complex one," says psychologist Peter Langman, author of Why Kids Kill: Inside the Minds of School Shooters. "Media doesn’t cause anyone to commit mass murder. If you need a role model, you will find one. It could be Hitler, it could be Charles Manson, it could be a character in a video game."

Kids who try to kill their peers or their parents tend to fall into the same three categories as school shooters, Langman says. They tend to either be psychotic or extremely mentally ill; have been heavily abused themselves; or exhibit psychopathic tendencies, meaning they don’t empathize with others and may be divorced from reality.

Of the two girls in Wisconsin, "I would think they would fall into one of the three categories," he says. "If they don’t, it would be much more difficult to understand what they did."

A ton of culture is now created online, so it follows that memes would hold the same appeal for violent criminals as Helter Skelter and Stephen King. Online communities may provide stronger reinforcement than other forms of media, Langman says, because other people are providing feedback. There is nothing inherently murderous about creepypasta, but the Wisconsin girls may have been encouraged by other creepypasta fans who also believed Slenderman was real.

That doesn’t mean creepypasta is an excuse, any more than "the devil made me do it."

"There is a line... between fiction and reality, and it is up to you to realize where the line is," the operators of the creepypasta wiki said in a blog post. "We are a literature site, not a crazy satanic cult." In other words: memes don’t kill people, people kill people.

Over at Something Awful, editor Zack Parsons begged readers "please do not kill anyone because of Slenderman." "The Slenderman fans can invest their dumb lives in the story just like Doctor Who fans or comic book fans or Welcome to Night Vale fans or any other fandom," he writes. "So long as you're not hurting anyone, it can be tolerated. We don't want your fandom's blood on our hands."