Snipers -- Kristine Kathryn Rusch

Snipers is a cold-case time-travel novel.  In Vienna in 1913 someone is killing people, one after another.  The killer was never caught.  In the present, Sofie Branstadter is writing a book about the murders.  She feels a personal connection because her parents were also killed by a murderer who was never caught.

The investigator in the original case was Johann Runge, the great-grandfather of pianist and composer Anton Runge.  Johann wrote his own book on the crimes, and eventually Anton and Sofie combine forces to delve into his records and the past.

When the corpse of one of the victims is disinterred, some amazing clues are discovered, pointing to a seemingly impossible conclusion.  The readers know it's the right one, however, as we've gradually become aware that the present of the book's narrative isn't our present.  (My favorite hint: Isaac Asimov is a well-known Russian writer.)  So the question of how changing the past affects the present becomes prominent.

This is a fast-moving thriller, and the ending implies that a sequel is in the works.  I'll be reading it.