It Was Professor Plum With The Knife In The Study!

Deciding how you're going to bump somebody off is the easy part. It's intertwining the lives of your suspects that's difficult. What's their back story? Their secrets? What makes them a suspect - the belief they'd kill another person? And what does this realization do to your protagonist?

These are the questions that aren't always easiest to answer. But you have to.

So right now it's a mystery in my brain, a puzzle that I HAVE to figure out. How to make it all work...