Hunting the Lady of the Night — C.M. Wendelboe

A decades-old murder of a Denver prostitute comes back to haunt Arn Anderson. Now working as a private investigator, he knows the case all too well. As a rookie Denver Metro detective, he was assigned to the cold case and, like many others before him, failed to solve the murder. When Denver cold-case detectives reopen the case, former witnesses begin to pop up dead, and all of them have connections to the deceased streetwalker. Suspects abound in Denver and Cheyenne, including a man running for governor, and the daughter of the dead prostitute, now a police detective herself. Arn must keep himself on this side of the grass long enough to solve the murder of the streetwalker. And the dead witnesses.