A Greenwich Village PI and her pit bull hunt down killers in these three smart, witty mysteries from a Shamus Award winner. In This Dog for Hire, the debut of New York private detective Rachel Alexander and her pit bull, Dash--short for Dashiell--a hit-and-run leaves a local painter dead and his show dog, a basenji, temporarily missing.   After cracking that case, Rachel and Dash return in The Dog Who Knew Too Much to investigate a t'ai chi teacher's fatal leap from a window. Rachel suspects there's more involved, as the woman would never have left her beloved Akita behind.   Rounding out the collection is A Hell of a Dog, in which Rachel, a former dog trainer herself, must find out who's killing off trainers at a professional gathering at a posh New York City hotel.   With comparisons to the mysteries of Laurien Berenson and Susan Conant, these novels--with "excellent" writing and a "nice touch of humor"--are an involving, atmospheric read for fans of strong female PIs, especially those with furry sidekicks (Library Journal).