First book in a mystery series that features a gay, black detective Pharoah Love. Besides the who dunnit plot, it depicts gay life in the 60's. Scarpetta series features Lucy, a lesbian FBI and ATF agent. Lucy's coming out happens in The Body Farm. Series of detective novels which feature a lesbian investigator.
Flashpoint is one.
Apparition Alley, Liberty Square, and Murder by Tradition are all, I think, part of the same series. The one I read was great. The Blue Place. Series featuring Jane Lawless, restaurant owner and amateur detective in Minneapolis. The presentation is more clearly as a detective story but the positive examples of lesbians are outstanding.