Without fully realising it, many of Gregg Olsen’s books are a series following the detective Kendall in Washington. Each book is a continuation of the other in terms of character development with a different crime to solve. Although each book can be read separately!
Victim six is somewhat unnerving, you are continually introduced to the killer and by half way through the book you know who the killer is. The catch, the police don’t. An absolute page turner that I read in one long train ride.