The 20-year-old nursing-home employee from suburban Pittsburgh who tried to assassinate former President Donald Trump was a registered Republican who packed explosives in the vehicle he drove to the campaign rally an hour from his home. Law enforcement officials were working Sunday to learn more about Thomas Matthew Crooks of Bethel Park, Pennsylvania, to determine what motivated him to open fire on the rally from a nearby rooftop, killing one spectator, before he was shot dead by the Secret Service. Read more: https://www.9news.com/article/news/nation-world/donald-trump-rally-shooting-who-was-gunman/507-e44b4879-d74c-4b2c-9749-e8f2696c1c7b ----- More local videos here: https://youtube.com/@9news Subscribe to NEXT: https://youtube.com/@Nexton9NEWS Stay connected: 9NEWS Website: https://www.9news.com/ Facebook: https://www.facebook.com/ilike9news Twitter: https://twitter.com/9NEWS Instagram: https://www.instagram.com/9newsdenver/ Download the 9NEWS App: https://www.9news.com/appredirect/ Sign up for the 9NEWSLETTER: https://www.9news.com/email 9NEWS (KUSA) is located in Denver, Colorado.