Mueller is about to cap an astonishing career in government. He was a Marine, a longtime prosecutor, and he transformed the F.B.I. post-9/11. But I’m thinking now about when he interrupted a steady rise in law in the ‘90s — in midlife — to become a homicide prosecutor here in Washington. He had a cushy job at a white-collar law firm and was an assistant attorney general before that. But he wanted to solve murder cases. He would go to crime scenes and do interviews. He liked examining bullet casings, he once said. He goes down as one of the most complicated yet unknown public figures in American life. I’m ready for a memoir!