Trump shooting motive, Secret Service security questions: What we know so far

null - What may have driven Thomas Matthew Crooks to carry out an apparent assassination attempt on former President Donald Trump? Investigators on Monday remained on the hunt for clues behind the 20-year-old suspect's shocking attack, as well as questions over security during the Pennsylvania rally. 

Crooks first came to law enforcement’s attention at Saturday's rally when spectators noticed him acting strangely outside the campaign event. The tip sparked a frantic search, but officers were unable to find him before he managed to get on a roof, where he opened fire, according to the Associated Press. 

Two spectators were critically injured, while a former fire chief from the area, 50-year-old Corey Comperatore, was killed. Pennsylvania's governor said Comperatore died a hero by diving onto his family to protect them.

The FBI said they were investigating it as a potential act of domestic terrorism, but the absence of a clear ideological motive by the man shot dead by the Secret Service led conspiracy theories to flourish.

"I urge everyone — everyone, please, don’t make assumptions about his motives or his affiliations," President Joe Biden said in remarks Sunday from the White House. "Let the FBI do their job, and their partner agencies do their job. I’ve instructed that this investigation be thorough and swift."

What's known about Thomas Matthew Crooks 

The FBI said it believes Crooks, of Bethel Park, Pennsylvania, had bomb-making materials in the car he drove to the rally – and said he acted alone. 

FBI officials said Sunday that they were combing Crooks' background and social media activities while working to get access to his phone. The chatting app Discord, a social media platform popular with people playing online games, said Crooks appears to have had an account but used it rarely and not in the last several months. There's no evidence he used his account to promote violence or discuss his political views, a Discord spokesperson said.

Crooks’ political leanings were not immediately clear. Records show Crooks was registered as a Republican voter in Pennsylvania, but federal campaign finance reports also show he gave $15 to a progressive political action committee on Jan. 20, 2021, the day Biden was sworn into office.

Crooks graduated from Bethel Park High School in 2022. 

In a video of the school’s graduation ceremony posted online, Crooks can be seen crossing the stage to receive his diploma, appearing slight of build and wearing glasses. The school district said it will cooperate fully with investigators. 

His senior year, Crooks was among several students given an award for math and science, according to a Tribune-Review story at the time.

Crooks tried out for the school's rifle team but was turned away because he was a bad shooter, Frederick Mach, a current captain of the team who was a few years behind Crooks at the school, told the Associated Press. 

Relatives of Crooks didn’t respond to numerous messages from the Associated Press. His father, Matthew Crooks, told CNN late Saturday that he was trying to figure out "what the hell is going on" but wouldn’t speak about his son until after he talked to law enforcement. 

An FBI official told reporters that Crooks' family is cooperating with investigators.

Several attendees of the rally reported to local officers that Crooks was acting suspiciously and pacing near the magnetometers, according to a law enforcement official who spoke on the condition of anonymity to the AP because they were not authorized to discuss the investigation. 

Officers were then told Crooks was climbing a ladder, the official said. Officers searched for him but were unable to find him before he made it to the roof, the official added.

Crooks used an AR-style rifle, which authorities said they believe was purchased by his father. Kevin Rojek, FBI special agent in charge in Pittsburgh, told the AP that investigators do not yet know if he took the gun without his father's permission.

Officer encountered Crooks on roof, AP reports

Butler County Sheriff Michael Slupe told the AP that a local officer climbed to the roof and encountered Crooks, who saw the officer and turned toward him just before the officer dropped down to safety. 

Slupe said the officer couldn’t have wielded his own gun under the circumstances. The officer retreated down the ladder, and Crooks quickly took a shot toward Trump, and that’s when Secret Service snipers shot him, according to two officials who spoke to AP on condition of anonymity to discuss an ongoing investigation.

Map of Trump rally, questions over security 

The shooting quickly prompted questions about how a gunman was able to open fire from the rooftop near the campaign rally. 

The roof where Crooks lay was less than 150 meters (164 yards) from where the former president and presumptive Republican presidential nominee was speaking, a distance from which a decent marksman could reasonably hit a human-sized target. 

That is a distance at which U.S. Army recruits must hit a scaled human-sized silhouette to qualify with the M-16 rifle.

Kevin Rojek, the agent in charge of the FBI’s Pittsburgh field office, told the AP that "it is surprising" the gunman was able to open fire on the stage before the Secret Service killed him.

Biden on Sunday also ordered a security review of operations for the Republican National Convention, which is proceeding as planned. The Secret Service said it was "confident" in the security plan, and no additional changes were planned.

The Associated Press contributed to this report.