Or for something a bit unusual, The Way of All Flesh by Ambrose Parry - a historic crime novel that is interwoven with the true story of the man who discovered the anaesthetic uses of chloroform, and Edinburgh's medical revolution.
And finally, for some crime that is a bit more light-hearted but still pretty dark, Carl Hiaasen is superb. A range of books (mostly self-contained but with some recurring characters) set in Florida exposing corporate greed and governmental corruption. Some proper weird extreme head-case characters in those books.