The Mercedes Coffin, by Faye Kellerman

When a young billionaire woman reads about a crime in the L.A. newspapers about a man found shot in the head and stuffed into the trunk of his Mercedes, it reminds her of a similar crime from 15 years earlier, the murder of her favorite high school teacher, a crime that had never been solved. She contacts the police & offers a multi-million dollar award for the solving of the cold case. Upon investigation of the two cases, detectives discover many similarities. Certain students from the high school where the teacher had worked seemed to be connected, including two aspiring rap artists and members of a late-1980s punk rock band. Detective Peter Decker, although not involved in the most current murder investigation, pokes around at solving the cold case which turns out to be connected to the more recent murder. After many interviews with the former students and the original (now retired) detectives (one of whom apparently commits suicide the day after being questioned), all the clues start to fall into place and everything points to a guy named Rudy Banks, the former lead-singer of the punk band. Just when police are ready to arrest him, Rudy is trailed to a motel where he holds 3 women hostage. After a very long stand-off, Decker convinces Rudy to let go of the hostages and walk out of the motel with hands up, but someone else (another former band member) shoots & kills Rudy as soon as he is out in the open. This is the first Faye Kellerman book that I have read, but it definitely won't be the last.