Marcia Muller

(The Sharon McCone Mysteries) &

Bill Pronzini

(The Nameless Detective series) are married (to each other); both are Grand Masters of the Mystery Writers of America. They jointly created the Carpenter & Quincannon series set in 1890s San Francisco and featuring Sabina Carpenter, a former agent with the Pinkerton Detective Service, and John Quincannon, formerly a Secret Service agent.
The Bughouse Affair
The Bodysnatchers Affair
The Spook Lights Affair
The Plague Of Thieves Affair