BETHEL PARK, Pennsylvania >> The motive behind a 20-year-old gunman’s attempt on the life of Donald Trump remained a mystery two days later with the suspect having been shot dead and the FBI unable to identify an ideology that may have driven him to attack the former president.

The FBI has taken the lead in an investigation of the shooting at a campaign rally in Pennsylvania that wounded the former president, overshadowing his Nov. 5 election rematch with President Joe Biden.

The Secret Service, responsible for protecting presidents and former presidents, went on the defensive today against criticism of its failure to detect the gunman whose shots wounded Trump in his right ear and killed a spectator.

“Secret Service personnel on the ground moved quickly during the incident, with our counter sniper team neutralizing the shooter and our agents implementing protective measures to ensure the safety of former president Donald Trump,” Kimberly Cheatle, the Secret Service director, said in a statement.

Biden ordered an independent review of how the gunman, who was shot dead by agents moments after opening fire, could have come so close to killing or severely wounding Trump despite the heavy security provided by the Secret Service at Saturday’s event in Butler, Pennsylvania.

The early details about the investigation into the gunman, Thomas Matthew Crooks, a nursing home aide, were sketchy.

He was a young man working an entry-level job near his hometown of Bethel Park, Pennsylvania. He graduated from high school in 2022 with a reputation as a bright but quiet classmate. His guidance counselor described him as “respectful” and said he never knew Crooks to be political.

The FBI said on Sunday that his social media profile contained no threatening language, nor had they found any history of mental health issues. They said Crooks acted alone and they had yet to identify a motive.

Crooks stands out among other recent, high-profile shooters who opened fire at schools, churches, malls and parades because he came within inches of killing a U.S. presidential candidate, something that has not occurred in decades.

Trump, who traveled in Milwaukee on Sunday to make final preparations for accepting his party’s formal nomination at the Republican National Convention this week, appeared both reflective and defiant late on Sunday.

Trump pumped his fist in the air several times and appeared to mouth the words “Fight! Fight! Fight!” as he descended the stairs from his plane.

In an interview during the trip, he said the realization that he came so close to being killed was sobering.

“That reality is just setting in,” Trump was quoted as saying by the Washington Examiner. “I rarely look away from the crowd. Had I not done that in that moment, well, we would not be talking today, would we?”

“I want to try to unite our country,” the New York Post reported Trump saying during the flight. “But I don’t know if that’s possible. People are very divided.”

SHOOTER WAS REGISTERED REPUBLICAN

On Saturday afternoon, Crooks was able to slip onto a rooftop location 150 yards (140 meters) from the stage where Trump was speaking in Butler, Pennsylvania. He then began firing an AR-15-style semiautomatic rifle, purchased by his father, officials said.

The gunfire killed a 50-year-old man, critically wounded two other spectators, and struck Trump’s ear.

The officials said “a suspicious device” was found in the suspect’s vehicle, which was inspected by bomb technicians and rendered safe.

A resident of Bethel Park, about an hour away from where the shooting occurred, Crooks was a registered Republican who would have been eligible to cast his first presidential vote in the Nov. 5 election.

Public records show his father is a registered Republican and his mother a registered Democrat, and that as a 17-year-old Crooks made a $15 donation to a Democratic Party cause.

Crooks was employed as a dietary aide at a nursing home at the time of the shooting, the home’s administrator said in a statement.

“We are shocked and saddened to learn of his involvement as Thomas Matthew Crooks performed his job without concern and his background check was clean,” said Marcie Grimm, administrator of the Bethel Park Skilled Nursing and Rehabilitation Center.

Two years ago, Crooks graduated from the local high school, where he showed no particular interest in politics, according to one classmate who asked not to be identified. Crooks’ interests centered on building computers and playing games, the classmate said in an interview.

“He was super smart. That’s what really kind of threw me off was, this was, like, a really, really smart kid, like he excelled,” the classmate said. “Nothing crazy ever came up in any conversation.”

Jim Knapp, who retired from his job as the school counselor at Bethel Park High School in 2022, said Crooks had always been “quiet as a church mouse,” “respectful” and kept to himself, although he did have a few friends.

He rarely came across Crooks because “he wasn’t a needy type kid,” Knapp said. Crooks was content to occasionally eat lunch by himself in the school cafeteria, said Knapp, who would engage such students to see if they wanted company.

“Kids weren’t calling him names, kids weren’t bullying him,” Knapp said.

Knapp said he never knew Crooks to be political in any way, even as other kids would sometimes wear Trump or Biden attire. He added that he couldn’t recall Crooks ever being disciplined in school.

Residents near the Crooks’ home described feeling shocked and unsettled that an assassination attempt had been linked to a person from the sedate city of 33,000 people.

“Bethel Park is a pretty blue-collar type of area, and to think that somebody was that close is a little insane,” said Wes Morgan, a 42-year-old who works at an investment management company and bikes with his children on the same street as the Crooks’ residence.

The officials said “a suspicious device” was found in the suspect’s vehicle, which was inspected by bomb technicians and rendered safe.

Additional reporting by Tyler Clifford, Katharine Jackson, Sarah N. Lynch, Richard Cowan, Caitlin Webber, Nandita Bose, Ismail Shakil, Joseph Ax, Andrew Hay Kanishka Singh.