Communications gaps, unguarded warehouses and a lack of written instructions opened an opportunity for a gunman at a rally in Butler, Pa., in July.

A Secret Service investigation has exposed new security breakdowns prior to the assassination attempt on Donald Trump that left two people critically injured and one person dead at a Pennsylvania campaign rally in July.

Ryan Wesley Routh, 58, faces charges of possessing a firearm despite a prior felony conviction and possessing a firearm with an obliterated serial number.