Again with Feeling - Bill Pronzini

We might not be doomed to repeat the past. But it's pretty likely.
When Dashiell Dawson Dane receives a phone call from his nemesis Vivienne Carver (okay, one of his nemeses), he's caught off guard—to say the least—by her request: help solve the murder of her brother, who disappeared almost thirty years ago. His gut tells him to say no. But with Bobby preparing to move out of Hemlock House, Dash sees the perfect opportunity for them to spend more time together, whether Bobby likes it or not.
The local police seem convinced that Vivienne was responsible for her brother's death—an opinion shared by some of her family. But the more Dash investigates, the more convinced he becomes that Vivienne is being set up. Secrets have been accumulating for decades, and the most dangerous lies, Dash knows, are the ones we want to believe the most. After all these years, answers might finally be within reach—and someone is willing to kill to keep the truth from coming out.