Newly released FBI documents, previously classified, offer new details about Thomas Matthew Crooks, a 20-year-old engineering student who tried to assassinate former President Donald Trump during a campaign rally in Butler, Pennsylvania, in July 2024. According to the 600-page report, Crooks practiced shooting at the Clairton Sportsmen’s Club, where he trained about once a week. His father initially described him as a "terrible shot," but Crooks practiced independently, often at shooting ranges. An employee at the Keystone Shooting Center near Pittsburgh told investigators that Crooks was "an odd duck" and "not someone they would want their daughter to spend time with." A member of the Clairton club also recalled seeing Crooks practice a 100-yard shot the day before Trump’s speech. The documents include interviews with Crooks’ family, teachers, classmates, and coworkers, along with law enforcement reports. They reveal that Crooks became interested in firearms during the COVID-19 pandemic, according to his father, Matthew Crooks, who was interviewed by investigators. Attempts to contact Matthew Crooks were unsuccessful. The documents were shared with the New York Post by the office of Senate Judiciary Committee Chairman Chuck Grassley, but Grassley’s office did not provide them to NBC News when requested. Grassley said in a brief interview that the motivation behind the attack remains unclear. During the attack, one person was killed and two others injured. Federal documents show that Crooks had been purchasing firearms and taking shooting classes at Keystone Shooting Center in the months before the rally. He enrolled in both basic and intermediate handgun courses and ordered gun parts online using the pseudonym "Bob Dole," according to his father. Crooks reportedly refined his aim over five years but had little interest in outdoor activities. Instead, he was described as a history enthusiast who could name all U.S. presidents and enjoyed discussing political history. Despite being a registered Republican, he donated $15 to a Democratic-aligned organization in 2021. Colleagues and classmates said he often wanted to be the "smartest person in the room," though he had few close friends and was occasionally bullied in high school. Crooks fired eight shots from an AR-15-style rifle six minutes into Trump’s speech on July 13, 2024. Trump was struck in the ear and required medical attention, though he was not seriously injured. Secret Service snipers located Crooks on a rooftop and killed him immediately. Before the attack, Crooks had been working as a dietary aide at a nursing home in Bethel Park and was planning to attend Robert Morris University to study engineering. Colleagues described him as kind and reliable at work, though he was described as socially reserved and sometimes kept to himself. A former roommate noted that Crooks had an interest in technology, building small boats and home security devices using 3D printers and computer components.