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. -- SNIP -- Crooks tried out for the school's rifle team but was turned away because he was a bad...