When one of the two girls accused of stabbing a Wisconsin classmate seven years ago walks out of the Winnebago Mental Health Institute today (Monday) she will be wearing a G-P-S monitoring device. A Waukesha County judge approved a conditional release plan for 19-year-old Anissa Weier last week. Weier has spent almost four years in the Oshkosh mental health facility after she admitted taking part in the 2014 stabbing of Payton Leutner. Weier and Morgan Geyser told investigators they were trying to please the fictional horror character Slender Man. Geyser attacked Leutner, stabbing her 19 times, while Weier cheered her on. All three girls were 12 years old at the time. Leutner survived.