Hitler's Angel — Kristine Kathryn Rusch

This much is true: Hitler was obsessed with his young niece, Geli Raubal. On 19th September, 1931, two years before he came to power, Geli was found dead of a gunshot wound in Hitler's apartment in an exclusive area of Munich. Her death was ruled a suicide, but the suspicion of murder remained long after she had been laid to rest. In 1971, Annie Pohlmann, a young American student, arrives in Germany to interview retired detective Fritz Stecher, who headed the original investigation. She gets more than she bargained for when Stecher reveals the whole story of a case that not only nearly kills him, but almost changed the course of history.