For Criminal Element, Liz Strange offers a brief overview of gay detective fiction, mentioning some of the better-known contributors to that subgenre--Joseph Hansen and Mark Richard Zubro, for instance--but leaving out many more.
If you’d like to a somewhat fuller look at this field of stories, check out Lori L. Lake’s piece from the November/December 2005 issue of Crimespree Magazine. Lake’s companion essay about lesbian detective fiction can be found here.
Still more information on the subject is available from Judith A. Markowitz’s 2004 book, The Gay Detective Novel: Lesbian and Gay Main Characters and Themes in Mystery Fiction. Chapter 1 of Markowitz’s work can be read here.