The Moorhead House — Kristine Kathryn Rusch

Dusty's Cleaning specializes in cleaning houses where horrible things happen. Suicides, murders, Dusty's seen them all. But she can't forget the scene at the Moorhead House.
So, when Dusty receives an invitation to a Christmas Party being held at the Moorhead House, she gets to revisit a horrible crime -- and figure out what exactly went wrong.
Chosen as one of the top ten stories of the year by the readers of Ellery Queen's Mystery Magazine.