The Wrong Side of Goodbye by Michael Connelly

As a private investigator, Harry Bosch has been secretly hired by wealthy Whitney Vance to find out before he dies if he has an heir. While in college in 1950, Vance was told by his girlfriend that she was pregnant, but after telling his father about the situation, the girlfriend disappeared and Vance never saw her again. Vance would like his vast fortune to go to his descendants. rather than have it in the hands of the board of directors of his company. Bosch is also part of the San Fernando Police Department reserve unit and is partnered with Bella Lourdes to try and discover a serial rapist in the area that they have nicknamed "Screen Cutter."  With these two cases, the reader accompanies Bosch as he uses his investigative techniques to find the answers he needs. A very satisfying entry in this long-running series.