The Waiting by Michael Connelly

Renee Ballard is the head of the LAPD's Open-Unsolved Unit. She and her team of volunteers work on a variety of cases at the same time. It turns out that the unit has a lead on a series on crimes from the early 2000's. Someone nicknamed the "Pillowcase Rapist" assaulted dozens of women and killed one (his last, in 2005). The team has gotten a familial DNA match, which means they can hopefully now trace and arrest the person who was responsible for the crimes. In addition, Harry Bosch's daughter, Maddie, also part of the LAPD, has come to volunteer for the unit. Maddie would like to move up the ranks, figuring the experience working with Renee will help her chances. Maddie also believes that she might have solved the infamous Black Dahlia case. Will both Renee and Maddie get what they're looking for? The Waiting  will be published in October.