A judge sentenced a 15-year-old Wisconsin girl to 40 years in a mental hospital on Thursday after she, along with another girl, admitted they tried to murder a classmate in order to please a fictional horror character named “Slender Man.” Morgan Geyser, 15, pleaded guilty in October to attempted first-degree intentional homicide in accordance with a plea deal to avoid serving time in prison. In 2014, Geyser and Anissa Weier, who was sentenced in December to 25 years in a mental health facility, lured their classmate Payton Leutner into a wooded park in Waukesha and stabbed her several times with...