Our Lady of Pain by Elena Forbes

Rachel Tenison is a successful art dealer in London, yet very secretive about her personal life. When she's found dead in Holland Park, police detectives Mark Tartaglia and his female partner, Sam Donovan, have few clues on who could've murdered her. They start interviewing those close to Rachel, including her best friend, Liz Volpe and her stepbrother, MP Patrick Tenison. Tartaglia comes away from the interviews with the feeling that neither is being entirely truthful. He also discovers that Rachel had a history of rough sexual relationships. Then a journalist notifies the police of a possible connection between Rachel's death and another young woman. Are the police dealing with one or two killers? Our Lady of Pain is the second book in the Mark Tartaglia/Sam Donovan series. The publisher on the cover of the book is calling it "A Barnes Murder Squad Mystery", but it really isn't (no similarities to McBain's 87th Precinct here). The focus of the book is on Tartaglia and Donovan and regular readers of English police procedurals (James, Rendell, George, Crombie, Peter Robinson, Susan Hill) should give this series a try.