Article continues below advertisementThe mystery surrounding Nancy Guthrie is only getting more complicated - and now, a new theory is raising even more questions.During an appearance on "The Interview Room," true crime podcaster Josh Diaz spoke with homicide detective Chris McDonough to weigh in on why no witnesses presented themselves in the ongoing investigation into the 84-year-old's disappearance.Article continues below advertisementSource: @savannahguthrie/InstagramNancy Guthrie has been missing since February 1.