Revenge

This is essentially a plot from a 1970s US television murder mystery. If you're interested, look up the Columbo episode "Blueprint for Murder"

Or dig their grave and bury them, dig another grave a couple yards away but leave it open, and give vague directions with an anonymous tip pretending to be an accomplice or something. Then when the police come they see the open grave they conclude that you've taken the body back out and presumably taken it somewhere else.