Plotting?

Does anyone have any good formats for actually plotting a murder mystery? I have the crimes and the killer all figured out, but I'm having trouble thinking of twists and turns the investigation can take, and of other suspects, etc. How do you get all the details figured out for your novel?

I make lists of clues as a checklist and check them off as I get to them. Because a lot of my mysteries are screenplays, I use the Hollywood Formula (a worksheet on Script Frenzy's site) to plot them. I also like the book Killer Fiction by Carolyn Wheat. Once I divided the story into several segments and filled in the plan in its proper segments.

Try this, it's an overview of the classic mystery structure, might help.

12 chapters??? each 17 pages in length???

I'm in deep, deep trouble then.

I don't follow that exact rule myself. xD It's just useful to have all the structural plot points laid out.