Shadow Side by Kristine Kathryn Rusch

Dan Retsler left Oregon for a reason. He never planned to return. But something draws him to accept an interview for police chief in a small town near the Oregon Caves. After all, the caves call the mountains their home, not the coast, where Retsler still fights haunting memories of strange creatures. But he soon discovers that something lurks in the shadows of this mountain town. Something linked to deaths too strange to be normal. Now, Retsler must investigate the type of crime he swore to leave behind—a crime that might decide his future once and for all.