Article continues below advertisementThe search for Nancy Guthrie remains ongoing as her disappearance passes the three-month mark - and now, a chilling new theory is raising even more questions.In an upcoming NewsNation special, NewsNation Presents: The Nancy Guthrie Mystery, journalist Brian Entin sits down with experts to break down what may have happened. One theory, in particular, is grabbing attention: the masked man seen on Guthrie's Ring camera may not even be alive anymore.