Law enforcement sources familiar with the federal investigation into the assassination attempt on former President Donald Trump say the gunman flew a drone over a field next to the grounds where Trump's Butler, Pennsylvania rally was held on July 13. Meanwhile, Secret Service Director Kimberly Cheatle testified Monday on Capitol Hill about the shooting, calling it the "most significant operational failure" at the agency in decades. CBS News' Scott MacFarlane and Anna Schecter have the details.
