What I try to do is write a story about a detective rather than a detective story. Keeping the reader fooled until the last, possible moment is a good trick and I usually try to play it, but I can't attach more than secondary importance to it. The puzzle isn't so interesting to me as the behavior of the detective attacking it.
Dashiell HammettNick: "Don't you think maybe a drink would help you to sleep?" Nora: "No, thanks." Nick: "Maybe it would if I took one.
Dashiell Hammett