The lawyer for one of 2 girls convicted in Waukesha's Slenderman stabbing attack says he'll take his case to the Supreme Court. Today, an appeals court rejected his argument that Morgan Geyser should have been tried in juvenile, not adult court. Geyser and a friend were 12 years old when they stabbed a classmate 19 times, they say to appease the fictional character, Slenderman. The girl survived.