Morgan Geyser and Anissa Weier, both 12, were charged as adults Monday with attempted intentional murder and held on $500,000 bail. They were arrested Saturday afternoon, a few hours after a cyclist found the bleeding victim on a sidewalk, stabbed 19 times.
Investigators said the three girls, classmates at Horning Middle School, went on a rollerskating outing Friday evening followed by a sleepover at Geyser's house to celebrate her birthday. The next morning they went to a nearby park.
Geyser and Weier told police they had encountered Slender Man on a horror website called Creepypasta Wiki, the Milwaukee Journal Sentinel reported. Geyser allegedly told police Slender Man had threatened to kill their families unless they killed for him.
Weier said they wanted to kill their friend and then walk to Slender Man's mansion, which they believed was in Nicolet National Forest, a huge stretch of wilderness in northern Wisconsin. A sheriff's deputy found them Saturday afternoon walking near I-94.
The original plan was to carry out the stabbing during the sleepover, Weier said, but she and Geyser decided to put it off. She told detectives that their first attempt was in a bathroom in the park and they then distracted the victim with a game of hide and seek.
"The bad part of me wanted her to die, the good part of me wanted her to live," she allegedly said.
Geyser described stabbing her friend and then wiping the knife down before putting it in her backpack.
"It was weird that I didn't feel remorse," she allegedly said.
Notable deaths of 2014 [PHOTOS]