Nancy Guthrie _ What Have Investigators Missed_

Nearly nine months after Nancy Guthrie disappeared from her Tucson home, investigators are still searching for the breakthrough that could identify her abductor. Retired NYPD Sergeant William Cannon examines the latest DNA findings, the FBI's involvement, lost surveillance evidence, overlooked investigative possibilities, and the tips that could still break this case. Have investigators exhausted every lead, or could critical evidence still be waiting to be discovered?