FBI agents continue to investigate the history of Thomas Michael Crooks, the 20-year-old gunman who was killed by a U.S. Secret Service sniper when he was attempting to assassinate former President Donald Trump during a campaign rally in Western Pennsylvania on Saturday, July 13. Trump suffered an ear injury during the attack, but only two days later, Trump — with his ear bandaged — appeared onstage during the first night of the Republican National Convention in Milwaukee. The attack is raising questions not only about the Crooks’ possible motivations, but also, about the fact that he was able…