If you ask a cop 'who's the scariest guy you faced down in an alley,' they tell you about someone you'd never expect. You also have to give your villains the same amount of detail, personality and point of view as your hero.

There's something built into the policing world that's high stakes and a great story engine. I love the morality of that world-the grey areas between the black and white, the twists and turns of an investigation, and the emotion of the victims. It's built-in storytelling.