By Bernd Debusmann, Tom Bateman and Tom McArthur, BBC News in Pennsylvania and London
The small Pittsburgh suburb of Bethel Park in Pennsylvania is reeling after the FBI named a young local man, Thomas Matthew Crooks, as the person who shot at Donald Trump during a campaign rally and shocked the nation.
Investigators believe that Crooks, armed with a semi-automatic AR-15 rifle, opened fire at the former president while he was addressing a crowd in Butler, Pennsylvania, leaving one audience member dead and two others wounded.
The 20-year-old kitchen worker was shot dead at the scene by a Secret Service sniper, officials said.
In his well-to-do hometown, however, neighbours are in shock, seemingly unable to grasp how a quiet young man is now accused in the shooting.
The FBI, for its part, has said only that Crooks was the “subject involved in the assassination attempt on the former president and that an active investigation was under way.”
Who was Thomas Matthew Crooks?
Thomas Crooks had not been carrying ID, so investigators used DNA and facial recognition technology to identify him, the FBI said.
He was from Bethel Park in Pennsylvania, about 70km (43 miles) from the site of the attempted assassination, and graduated in 2022 from Bethel Park High School with a $500 (£385) prize for maths and science, according to a local newspaper.
Crooks worked in a local nursing home kitchen just a short drive away from his home, where staff members have said that he passed a background check and raised no concerns.
State voter records show that he was a registered Republican, according to US media.
He is also reported to have donated $15 to liberal campaign group ActBlue in 2021.
He had a membership at a local shooting club, the Clairton Sportsmen’s Club, for at least a year, the club confirmed to the BBC.
The vast club is based south of Pittsburgh and is “one of the premier shooting facilities in the tri-state area” of Pennsylvania, Ohio and West Virginia. It has more than 2,000 members.
It has multiple gun ranges, including a high-power rifle facility with targets up to 171 metres away.
The club’s owner, Bill Sellitto, told the BBC that the shooting was a “terrible, terrible thing”. Access to the club is tightly controlled, with only members allowed inside the sprawling facility.
“Obviously, the club fully admonishes the senseless act of violence,” attorney Robert S Bootay III, who represents the organisation, told the BBC.
Law enforcement officials believe the weapon used to shoot at Donald Trump, an AR-style rifle, was purchased by Crooks’ father, according to investigators.
It is unclear how the weapon came into his son’s hands, although there is no suggestion the father had any inkling of what was to take place.
Speaking on condition of anonymity, two officers told AP that Crooks’ father bought the weapon at least six months ago.
Authorities also say that Crooks purchased a box of ammunition containing 50 rounds on the day of the rally, reports CBS, the BBC’s US news partner.
According to US media reports, Crooks was wearing a T-shirt from Demolition Ranch, a YouTube channel known for its guns and demolition content. The channel has millions of subscribers featuring videos on different guns and explosive devices.
The day after the shooting, law enforcement sources also told CBS that suspicious devices were found in Crooks’ vehicle.
According to CBS, the suspect had a piece of commercially available equipment that appeared capable of initiating the devices.
Bomb technicians were called to the scene to secure and investigate the devices.
What was his motivation?
Having established Crooks’ identity, police and agencies are investigating his motive.
“We do not currently have an identified motive,” said Kevin Rojek, FBI Pittsburgh special agent in charge, at a briefing on Saturday night.
The inquiry into what took place could last for months and investigators would work “tirelessly” to identify what Crooks’ motive was, Mr Rojek said.
Speaking to CNN, Crooks’ father, Matthew Crooks, said he was trying to figure out “what the hell is going on” but would “wait until I talk to law enforcement” before speaking about his son.
Crooks’ family is cooperating with investigators, according to the FBI.
Police sealed off the road to the house where Crooks lived with his parents.
A neighbour told CBS that officers evacuated her in the middle of the night with no warning.
Bethel Park Police said there was a bomb investigation surrounding Crooks’ home.
Access to the area remains tightly controlled with police vehicles blocking the roads. Only residents have been allowed in or out.
Law enforcement sources told CBS that they believe some degree of planning ahead of the shooting.
How much time was spent in that planning, however, remains the subject of an ongoing investigation.
Police believe he acted alone, but are continuing to investigate whether he was accompanied to the rally.
What kind of person was he?
So far, a confusing – and at times conflicting – picture has emerged of who Crooks was as a person.
Speaking to local news outlet KDKA, some young locals who went to school with him described him as a loner, who was frequently bullied and sometimes wore “hunting outfits to school”.
Another former classmate of his, Summer Barkley, cast him differently, telling the BBC that he was “always getting good grades on tests” and was “very passionate about history”.
“Anything on government and history he seemed to know about,” she said. “But it was nothing out of the ordinary… he was always nice.”
She described him as well-liked by his teachers.
Others simply remembered him as quiet.
“He was there but I can’t think of anyone who knew him well,” one former classmate, who asked to remain nameless, told the BBC. “He’s just not a guy I really think about. But he seemed fine.”
Another classmate, who similarly did not want to be identified, described him as “intelligent but a little weird.”
Staff at Angelo’s Pizza, a restaurant in Bethel Park, told the BBC they were familiar with Crooks.
The restaurant’s owner, Sara Petko, said that staff members – some of whom were his classmates – thought he was a “loner” but that they were having trouble understanding how an otherwise quiet man turned to violence.
“It’s just crazy, and too close for comfort,” she said. “To think that someone at basically the start of his life could do this.”
Jameson Myers, a former member of the Bethel Park High School varsity rifle team who graduated alongside Crooks in 2022, told CBS that Crooks did not make the team.
“He did not even make the junior varsity team after trying out,” Mr Myers added. “He never returned to try-outs for the remainder of high school.”
Another former classmate told ABC News he “shot terrible” and “wasn’t really fit for the rifle team”. The school district said there was no record of Crooks trying out for the team and he “never appeared on a roster”.
Mr Myers remembers Crooks as seemingly a “normal boy” who was “not particularly popular but never got picked on or anything”.
“He was a nice kid who never talked poorly of anyone and I never have thought him capable of anything I’ve seen him do in the last few days.”
Max Smith, who took an American history course with Crooks, told the Philadelphia Inquirer that his former classmate “definitely was conservative”.
Mr Smith recalled a mock debate in which they both took part, saying: “The majority of the class were on the liberal side, but Tom, no matter what, always stood his ground on the conservative side.”
“It makes me wonder why he would carry out an assassination attempt on the conservative candidate,” he said.
Other community members said simply that they were shocked that the alleged perpetrator of the shooting could have come from the quiet, tree-lined streets of Bethel Park.
Among them was Jason Mackey, a 27-year-old local man who lives near the Crooks residence and worked at his school while he was a student.
While Mr Mackey said that he did not know Crooks personally, he is still reeling from a sense of disbelief.
“It’s just shocking. You wouldn’t think an event of this magnitude would come right out of your backyard,” he said. “It’s just a crazy situation.”
Who were the victims in the shooting?
One person was killed and two others were injured in the shooting.
All three victims are adult men and were audience members, CBS News reports.
At a news conference on Sunday, Pennsylvania Governor Josh Shapiro identified the deceased victim as Corey Comperatore, a 50-year-old volunteer fire chief who was killed when he “dived on his family” to protect them.
He said that Comperatore “died a hero”.
The two people injured in the attack have been identified as 57-year-old David Dutch and 74-year-old James Copenhaver.
Both men are Pennsylvania residents and are in stable condition.
A GoFundMe page, organised by the Trump campaign’s national finance director Meredith O’Rourke, was set up in the hours after the attack with donations going to the families of the injured.
It has so far raised more than $340,000 (£267,000).
In a post to his Truth Social platform, Trump said he was “shot with a bullet that pierced the upper part of my right ear” and said he felt the bullet “ripping through the skin”.
Blood was visible on Trump’s ear and face as protection officers rushed him away.
Trump is “doing well” and is grateful to law enforcement officers, according to a statement published on the Republican National Committee (RNC) website.
He travelled to Milwaukee, Wisconsin on Sunday, a day after the shooting, to attend the Republican National Convention.
How far was he from Donald Trump?
One witness told the BBC that he had seen a man – believed to be Crooks – with a rifle on the roof of a building before Trump was shot.
Video footage obtained by TMZ shows the moment the shooting began.
The assailant opened fire with “an AR-style rifle”, CBS News reports.
Law enforcement sources also told CBS that he was reported by a bystander and identified as a suspicious person by police, but that officers lost track of him before the shooting began.
A Secret Service sniper returned fire and killed the gunman, officials said.
Footage later shows armed officers approaching a body on the roof of the building.