A disturbing internet creation is being blamed for a series of near fatal stabbings - carried out by children.
In the first instance, Anissa Weir and Morgan Geyser, both 12, are alleged to have brutally attacked their friend of the same age after a slumber party, stabbing her 19 times and leaving her in the woods in Wisconsin.
Miraculously, the unnamed victim survived and managed to crawl to a nearby road where she was found by a cyclist who raised the alarm.
Scroll down for a gallery of Slender Man pictures
The suspects have claimed they were trying to prove the existence of a fictional horror character called “Slender Man”.
Both have been charged as adults with first-degree attempted homicide and face up to 60 years in prison if convicted.
According to the Associated Press: “One of the girls told an investigator they began planning to kill their friend in December.
“The other girl told police they decided to kill her so they could become proxies of Slender Man, who would accept them and let them live with him in his (make-believe) mansion in the Nicolet National Forest.
“The other girl said she sees Slender Man in her dreams She said he watches her and can read her mind and teleport.”
One is said to have told detectives she regretted the attack, revealing: "The bad part of me wanted her to die, the good part of me wanted her to live."
The woman, who asked not to be identified told WLWT News 5 her daughter had a history of mental health issues but that she had never believed she would harm her.
She added the teenager, whose journals referenced demons, being insane and falling into darkness, dressed in a hood and a mask for the attack.
But who, or what exactly is Slender Man, and how is a fictional character inspiring children to attempt to kill?
According to Know Your Meme, which tracks internet trends, Slender Man came into being in 2009 after an entry for a competition on the online forums Something Awful to create “paranormal pictures” was submitted by Eric Knudsen.
The popularity of the character promptly exploded, with numerous fan sites creating their own Slender Man stories, putting him in fan art, videos, video games and other media. Some websites host what appear to be photographs of him, lending the creation an air of authenticity.
Shira Chess, an assistant professor at the University of Georgia who has researched Slender Man's origins told the Associated Press: "It feels real. A 12-year-old isn't potentially going to know the whole origin of the story."
Knudsen’s creation appears to be a mysterious figure who stalks children.
He is most distinctive for his blank, featureless face, his extreme height and dapper appearance – (“He often keeps his long, pale hands crossed politely behind his back or hanging loosely at his sides. He has long coattails which he lets flow proudly. He wears long dress shoes, which are always shined a perfect, gleaming black”).
According to some descriptions, he has between four and eight long black tentacles, which protrude from his back. He is also said to be capable of causing memory loss, insomnia, paranoia and coughing fits.
The two 12-year-olds charged with first degree attempted homicide reportedly told detectives they learned about Slender Man on online fiction forum Creepypasta Wiki.
Literature on the site reads: “Whether he absorbs, kills, or merely takes his victims to an undisclosed location or dimension is also unknown as there are never any bodies or evidence left behind in his wake.
“His face is pale and slightly ghostly and almost appears to have been wrapped in a type of gauze or cloth. His facial features are also an object of debate and many people believe that his face looks different to each person, if it is seen at all.”
The site has distanced itself from the Wisconsin stabbings, issuing the following statement to CNN: "This is an isolated incident, and does (not) represent ... the Creepypasta community as a whole.
"This wiki does not endorse or advocate for killing, worship, and otherwise replication of rituals of fictional works. There is a line of between fiction and reality, and it is up to you to realise where the line is. We are a literature site, not a satanic cult."
Claire Lilley, Head of Child Online Safety at the NSPCC told Huffington Post UK via email: “Things are not always what they seem online and children can get sucked into unhealthy and dangerous situations.
"While the web is a wonderful resource it also harbours risks. Parents should talk to their children about what they are viewing.
"And it's vital youngsters know who to turn to if they ever feel threatened or frightened by any online encounter. This way we can hopefully avoid more tragedies like this.”
What's your take on the Slender Man phenomenon? Let us know in the comments below...