Chilling images are the biggest break so far in the Nancy Guthrie case. Here’s what stands out to law enforcement experts

By Dakin Andone, CNN (CNN) — New images showing an armed, masked individual outside the Tucson, Arizona, home of Nancy Guthrie have given new life to the search for the 84-year-old – and may offer investigators important clues about the subject’s identity. The video and images released by the FBI Tuesday are the biggest break