 As for the shooter, his name was Thomas Michael Crooks, and he was 20 years old. ABC's Aaron Katursky is in his hometown. The FBI is confident that Crooks acted alone, but they still don't know why he acted at all. He was on no FBI radar, had no criminal record, and what they've seen so far of his digital history has offered no useful clues as to why he carried out this historic act of political violence.