Before he opened fire late Sunday — killing at least 50 people at a country music festival on the Las Vegas Strip — the gunman Stephen Paddock lived a quiet life for years in a small town outside Las Vegas. A retired man, Paddock often visited Las Vegas to gamble and take in concerts, his relatives said. Public records show he was a licensed pilot who owned two planes. And he had a hunting license from Alaska. For several years, he appeared to live in Mesquite, Tex.