After three days, an enigmatic portrait emerged of the 20-year-old man who came close to killing former President Donald Trump with a high-velocity bullet: He was an intelligent loner with few friends, an apparently thin social media footprint and no hints of strong political beliefs that would suggest a motive for an attempted assassination.

Even after the FBI cracked into Thomas Matthew Crooks’ cellphone, scoured his computer, home and car, and interviewed more than 100 people, the mystery of why he opened fire on Trump’s rally Saturday, a bullet grazing the GOP nominee’s ear, remained as elusive as the moment it happened.

He sat by himself, didn’t talk to anyone, didn’t even try to make conversation,” said 17-year-old Liam Campbell, echoing the comments of classmates who remembered the shooter in this quiet community outside of Pittsburgh. “He was an odd kid,” but nothing about him seemed dangerous, he added. “Just a normal person who seemed like he didn’t like talking to people.