The Hangman's Son — Barry B. Longyear

Trade Paperback, Joe Torio Mystery, 413 pages. When Major Crimes Unit Commander Al Dockery finds himself dealing with three seemingly unrelated series of killings at the same time, he calls his invalided former partner, Joe Torio, out of therapy. Sgt. Torio may be just as crazy as the killers Dock needs to stop, but Joe Torio's brand of crazy catches killers. The trick in this case is not to lose Joe in the process.