More than six years after a Florida college student randomly murdered a Martin County couple inside their garage, gnawing on one of the victims’ faces in a gruesome case that made global headlines, a judge has found him not guilty by reason of insanity. Former Florida State University student Austin Harrouff, 25, killed strangers John Stevens and Michelle Mishcon at their Martin County home in August 2016 in the midst of what his attorneys have described as an “acute psychotic episode.”…