These mystery and crime paperbacks from the 40s featured crime scene maps on the back and some wonderful cover illustrations, especially those by Gerald Gregg. There are lots of his covers here on Flickr.
Dark Passage by David Goodis 1948, cover by Gerald Gregg. via ebay
A Halo for Nobody by Henry Kane 1948 via ebay
The Body Missed the Boat by Jack Iams 1949 via ebay
The scene of the crime
Murder in Mesopotamia by Agatha Christie 1947 via ebay