The rooftop where a gunman shot at Donald Trump during a weekend campaign rally was reportedly flagged as potentially vulnerable by the Secret Service in the run-up to the event.
The security agency was aware that the building next to the outdoor venue where the campaign was taking place in in Butler, Pennsylvania, posed a risk, according to NBC News.
“Someone should have been on the roof or securing the building so no one could get on the roof,” a former senior Secret Service agent said to be familiar with the planning told the US news outlet.
The gunman - named by the FBI as 20-year-old Thomas Matthew Crooks - had his father’s AR-style rifle and was perched atop a nearby roof when some rallygoers pointed him out to local law enforcement, according to two law enforcement officials.
A local law enforcement officer climbed to the roof and found Crooks, who pointed the rifle at the officer.
The officer retreated down the ladder, and the gunman quickly fired towards Mr Trump, the officials said. That is when US Secret Service officers shot him dead.
Questions are being asked how the gunman got so close in the first place.
Kevin Rojek, the agent in charge of the FBI’s Pittsburgh field office, said “it is surprising” the gunman was able to open fire on the stage before the Secret Service killed him.
Bomb-making materials were found inside both Crooks’ vehicle and at his home, officials said. The FBI described the devices as “rudimentary”.
His motive remained unclear. Crooks was not on the FBI’s radar, and he was believed to have acted alone. Investigators combed through his social media accounts but found no immediate threatening writing or posts, or communications indicating an ideological motive. His family is understood to be co-operating.
Crooks’ political leanings were also unclear. Records show him registered as a Republican voter in Pennsylvania, but federal campaign finance reports also show he gave 15 dollars to a progressive political action committee on January 20 2021, the day Mr Biden was sworn in.
The absence of a clear ideological motive added to deepening questions about the shooting.
President Joe Biden ordered an independent security review of the attack, which killed a bystander and critically injured two others.
The FBI was investigating the shooting as a potential act of domestic terrorism.
The former US leader arrived in Milwaukee on Sunday evening for the convention, which begins on Monday.
