After reading this, if you think I'm a terrible person, it's probably because I am a terrible person.
Basically, I'd write about my mayor character slowly killing off the inhabitants of my town. It would be sort of like a twisted game; to see if the mayor can murder all of the villagers before one of them finds out who the killer is. If they get too suspicious, they're the next to go. I'd kill them in ACNL related ways, though. For example, I could trap Willow in a pitfall and quickly bury her whilst she's struggling. Or, maybe I could run into Goldie's house whilst being chased by bees but I'd forget to close the door. Once the bees were inside, I'd escape, slam the door and listen to Goldie scream. She would be stung to death, it would be seen as a freak tree-shaking related accident and I'd get off with no blame.
I'm evil.