 His name is Thomas Matthew Crooks. He is 20 years old. He's from Bethel Park, Pennsylvania, which is about 40 miles from the scene of the shooting. He was generally regarded in school as a quiet, intelligent guy, and he'd been working as a dietary aide at a local nursing home. And investigators told us that he was interested in chess and that he had recently taken up computer coding. And what did the authorities say about his motive?