This aerial photo taken on July 15 shows the site of the Trump campaign rally in Butler, Pennsylvania.
Here are several issues and problems identified by CNN that could or should have been addressed before the attack on former President Donald Trump.
In addition, CNN Chief Law Enforcement and Intelligence Analyst John Miller provided his analysis of some of the issues and their importance.
A source told CNN that about 19 minutes before the shooting, law enforcement was trying to locate the shooter, but they could not find him until he was on the roof.
Building access not controlled: No one stopped the shooter from reaching the roof of the American Glass Research building.
Persons:
Gene J, Donald Trump, John Miller, Shooter, WTAE
Organizations:
Trump, CNN, Intelligence, United States Secret Service, Service, WTAE, Pennsylvania State Police, American Glass Research
Locations:
Butler , Pennsylvania