(NEWSER) – Two 12-year-old girls who allegedly stabbed their friend in the woods of Waukesha, Wis., offered a chilling explanation for their actions: They'd been driven by "Slender Man," a mythical figure who's made the rounds on the Internet since 2009. But there are no deep, mysterious roots to this legend: The Washington Post delves into "the complete, terrifying history ... of the Internet meme," finding that a little digging reveals exactly who made it up and when. It all started with a forum on humor site Something Awful asking users to "create paranormal images through Photoshop." That resulted in Slender Man, the creation of one Victor Surge, aka Eric Knudsen, who offered disturbing stories of a guy with tentacles. Knudsen is now seeking a copyright on the story, CNN reports.