I just recently started reading (and then skimmed the rest...I'm impatient) Patricia Cornwall's book about the Jack the Ripper case in Victorian England. She's identified the killer! I'll not spoil the book for you. It's really good. What did frustrate me about it was that she went off on tangents quite often, but since I do the same thing, often to illustrate or prove a point or to explain th significance of the main story, I can't complain too loudly. You might find it too irritating.
I'd give you the title, but I don't have it in front of me. Check back later. I'll consult the minds at the online bookstore.