The Waiting - Michael Connelly

LAPD Detective Renée Ballard gets a DNA hit in a case that has gone unsolved for twenty years. A recently arrested man is genetically related to a serial rapist who terrorised the city of angels. But when the relative is revealed, it is the last person you want to accuse unless the evidence is watertight. With the help of the newest volunteer to the cold case unit - patrol officer Maddie Bosch, Harry's daughter - Ballard finally has another badge on the team. But Maddie has an ulterior motive for getting access to the city's library of souls. Because some crimes have been waiting to be solved longer than others