Dark Day. The Brandon Hall Series, #3

Hall's on his first official case after becoming a private investigator. It's supposed to be a simple, and boring case. All he had to do was follow a cheating husband and take some pictures. But for him, things are never that simple. He quickly gets swept up in a murder case, which leads to the name of an out-of-town hitman. As Hall investigates and tries to find the elusive hitman, more bodies pile up, and the name of one man keeps entering the picture.
A man named Ripper who's behind it all. But is Ripper actually a new foe, or is he the same criminal mastermind that Hall has run into before with a different name?