Although investigators have searched for clues, they may never know what drove Thomas Matthew Crooks to attempt to assassinate former President Donald Trump. The attempted assassination remains a mystery after Crooks, 20, was shot dead by the Secret Service at the 78-year-old ex-president’s rally in Butler, Pennsylvania on Saturday, July 13. An insider said: “The guy’s a ghost who kept to himself. “It’s likely we’ll never know for sure what drove this young man to try to commit a historic murder.” Crooks did not regularly post on his social media profile, but he did register himself as a Repub…