Murder In High Place - R.B. Dominic
R B Dominic (and Emma Lathen -- same author duo) wrote some of my favourite mysteries. The hero is a congressman and the stories examine an American political issue, and examine it brilliantly. It's not preachy, but there are sharp comments, great characters and the mystery is always solid. Now that the mysteries are ageing (Murder in High Place was published in 1970) they're also a window into history. I thoroughly recommend any of their books that you can get hold of. I only just found a copy of Murder in High Place via Better World Books. Wonderful story written in their typical good humoured style.