User blog comment:Paul.rea/Teen Wolf News 021716/@comment-27038309-20160219114956/@comment-5285305-20160219210038

IIRC, the Dread Doctors were hiding bodies in the tunnels - cleaning up Betty's mess. So they probably sweeped up the place before the cops got to the crime scene. As far as the school is concerned, those people are missing, not murdered on campus.