 Live from NPR News in Washington, I'm Dave Mattingly. The Secret Service is investigating how a gunman made his way onto a rooftop in Butler, Pennsylvania, outside former President Donald Trump's rally on Saturday. The FBI believes the suspect, 20-year-old Thomas Matthew Crooks, acted alone when Trump was wounded in his right ear and three attendees were shot, one fatally. The FBI says it has Crooks' cell phone as it investigates a motive.