not a fully fledged idea like some of these are, more of a concept/prompt. also you could do it with just one person.

person one is a murderer, but also has the ability to stop time. this makes for unbreakable alibis and essentially the perfect crime, as long as they don't leave any damning evidence at the scene.

so basically just write whatever with it! you could just kinda generally follow it, you could do gore with a few mentions of the time thing, you could add a second person and make them either the alibi/the victim, like i said i hadn't really thought it through too much so if anyone wants to use it i'd love to see what you do with it (: