Successful crime is about being undetected. Being undetected is about taking advantage of things you know that other people don’t.
Therefore anything the criminal knows about that other people don’t is a good canvas for crime--anything known and grasped by the general public is a bad canvas for crime. Therefore any subject you, the Host, know better than the average citizen is a place ripe with opportunity for criminal exploitation. Dick Francis knows more about horse racing than you—so he wrote like forty books about crime and horse-racing.
I know a professional autograph hound. Here’s what he does: he looks on the internet for restaurants where celebrities hang out, he tells parking attendants and waiters there he’ll pay them for a tip if they see a celebrity—they call, he rolls up, he tries to get an autograph. If he does: he sells it online for more than he paid the waiter.
There are 100 crime stories in there, easy. In one, maybe a stalker claims to be an autograph hound? In another, maybe a murderer pretends to be a celebrity to catch an autograph hound? In another, maybe the apparently-suspicious waiter isn’t really the murderer, he just didn’t want to admit he snuck off to call the hound? In another maybe it’s just the best way to figure out where a dead celebrity was before they died was to ask the hound where the autograph came from?
Whatever your little world is, there’s a crime story in there. You know where the security tape goes at 7-11 at night? You know how a book goes from a warehouse to a book store? You know where the teachers go to smoke? You have secret knowledge—you can start to build a crime.