Monkeewrench by P. J. Tracy

People are dying for the new computer game by the software company Monkeewrench. Literally. With Serial Killer Detective out in limited release, the real-life murders of a jogger and a young woman have already mimicked the first two scenarios in the game.
But Grace McBride and her eccentric Monkeewrench partners are caught in a vise. If they tell the Minneapolis police of the link between their game and the murders, they'll shine a spotlight on the past they thought they had erased-and the horror they thought they'd left behind. If they don't, eighteen more people will die...