On a Saturday morning in September, 2010, my younger brother Austin took out a handgun I hadn't known he owned, told his wife to call the police, and gave her a special password with which to identify him. "They're coming for me," he said, "but I'll keep you safe." At least, that's the story his wife told us at the time. From there, details get a bit hazy, but the facts are these: my brother…