The FBI has identified the gunman in the deadly shooting Saturday at a Pennsylvania campaign rally that injured Donald Trump in an assassination attempt as 20-year-old Thomas Matthew Crooks, but hasn't yet revealed a motive.
"This remains an active and ongoing investigation," the FBI said in a statement early Sunday.
The House Oversight Committee has already called the director of the Secret Service to testify about the attempted assassination in the wake of the security breach, and House Speaker Mike Johnson has promised a full investigation.
Crooks, a resident of the Pittsburg suburb of Bethel Park about an hour's drive from the Pennsylvania rally, was a registered Republican, according to records. He would have been old enough to vote for president for the first time in the upcoming election.
But a Thomas Matthew Crooks is also listed as donating $15 to the Progressive Turnout Project through the Democratic ActBlue organization, according to campaign finance records.
Crooks has no apparent criminal record.
Crooks graduated in 2022 from Bethel Park High School, according to the Pittsburgh Tribune-Review, and received a $500 "star award" from the National Math and Science Initiative. He worked as a dietician at a local nursing home.
A student who didn't share classes with Crooks told AP that he was viciously bullied in high school.
"He was bullied almost every day," said David Kohler. "He was just an outcast, and you know how kids are nowadays." Students mocked him for what he wore, including hunting outfits, according to Kohler.
FBI officials said Sunday they haven't yet found any social media posts or other threatening writing indicating a troubling underlying ideology explaining his actions.
Crooks' father, 53-year-old Matthew Crooks, told CNN that he would not comment on his son until he spoke to law enforcement. He said he was trying to figure out "what the hell is going on."
Thomas Crooks fired on the former president from a rooftop outside the arena minutes after Trump began his address to the crowd in Butler Park in Butler, Pa., in an attack that killed a spectator and critically injured two others.
Trump, whose face was spattered with blood after the shooting, said later he was shot in the right ear, and that he could feel the bullet "ripping through the flesh."
He and his campaign reported afterward from a nearby hospital that he was "fine." Trump thanked law enforcement officials for their "rapid response."
The Secret Service confirmed that Crooks fired "from an elevated position outside of the rally venue."
Crooks was fatally shot on the scene by Secret Service agents, and an AR-style firearm was recovered at the scene. The FBI believes the gun had been legally purchased by Crooks' father, an official said at a second press conference Sunday.
The family is cooperating with investigators, the Associated Press reported.
It's unclear how the gunman managed to scale the roof without the notice of Secret Service guarding Trump.
Crooks was apparently captured on video lying prone on the rooftop on video. At least one spectator claimed to have seen him "bear crawling" on the roof.
The Federal Aviation Administration said on Sunday that the airspace over Bethel Park was closed "effective immediately" for security reasons.