Have you been urinating in the parking lot?

This is from a novel:

The police is called because a man has urinated in a parking lot. When the police arrive 5 minutes later they ask the man: "Have you been urinating in the parking lot, sir?"

My question is: why is the continuous used? It only happened once and urinating is a short action. Is it used to express criticism?

Could the policeman have asked: "Have you urinated in the parking lot, sir?"