If you’re writing a crime novel, then dark and awful things, sourced from the madness of your soul, need to happen. A crime novel without an offence isn’t a crime novel, and a straight-up murder isn’t going to cut it anymore. Give your culprits unique and differing reasons to be offenders. The crooked character in a story never knows they’re the antagonist. In their story, they’re the right guy. The protagonist is as active as the forces of antagonism they are opposing. Give them something to go up against, so they have a juicy match. As I said, ‘A murder or nine, is more interesting.’
*Note: Killers never kills someone because they’re mad, there is always an extra reason to pull the character out of complacency and into murder.
An exercise in this model would be to take the ‘Little Red Riding Hood’ story and re-write it in the first person POV from the wolf’s perspective. While in that mode I’m sure you will see that the wolf can think and do many things that are fine with him.