Surveillance video of a masked, armed figure outside the Tucson home of Nancy Guthrie has become a key focus in the search for the missing 84-year-old.

The images show a person wearing gloves, a mask and a backpack appearing to tamper with the camera at Guthrie's front door. "We believe she is still alive," Savannah Guthrie said.

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The CCTV visuals also show pedestrians and motorists cautiously navigating around the stray animal moments before the ...