The Hunter by John Lescroart

Private Investigator Wyatt Hunt was perfectly happy with his adoptive parents, well-adjusted, with no obvious problems. One day, he gets a test: "How did your mother die?" Curiosity more than anything leads Wyatt to investigate his birth parents leading to the discovery that his mother was murdered forty years earlier. Possibly by his birth father. Determined to get to the truth of this mystery, Wyatt finds he has opened a real can of worms, plus getting one of his investigators murdered. Can a forty-year old murder have these consequences? Lescroart had this reader unwilling to put the book down. Twisted, seemingly impossible, one clue leads to another in this thrilling murder mystery. A great read.