Murder in the Castro by Elaine Beale

Lou fights police, and tries to clear a friend of murdering a gay co-worker.

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From Library Journal
First novelist Beale introduces amateur sleuth Lou Spencer, a red-headed British transplant who works as office manager for a nonprofit antihate organization in San Francisco. Lou begins her sleuthing career when police accuse her best friend, a gay co-worker, of murdering his ex-lover—also a co-worker. Lou must battle phone harassment, police bigotry, political tensions, and her growing attraction to a Latina cop to expose the real culprit. Solid work, decent plot, and an engaging protagonist recommend this for most collections.
Copyright 1997 Reed Business Information, Inc.