You should first ask for an explanation and justification of the so far alledged misbehavior. You could accuse and threat someone on false claims. If the person fails to provide a valid explanation and justification the demonstration of the existance of a problem will have been made by itself. No need the explicitly threat anyone. Threatening should be done only in phase 2 after the problem as been acertained by both parties and the person has failed to correct what could have been a simple misunderstanding or an accident.