Ok, so I have a detective, a villian, a victim, and a scapegoat (to connect the detective to the murder). Now I have to flesh out a cast of three dimensional characters, and this is going to be a rather large cast, I think. The hardest part is deciding who and what I need.
I know I need to have a romantic interest for the hero, and I have an idea for that. I need a mentor, and I have an idea for that one too. I guess I'll start there and see what happens after.