Slender Man” stabber Morgan Geyser will be sent back to a Wisconsin mental institution after her conditional release was revoked following her brazen escape from a group home last month. The 23-year-old — who viciously knifed a fellow sixth-grade student over a decade ago to please a made-up internet boogeyman — appeared in Waukesha County Circuit court Tuesday where a judge granted the state’s Department of Health Services’ request to