How important do you have to be to have been "assassinated" instead of "murdered"? If the motivation is political, then it's assassination. Otherwise, it is murder. You cannot be assassinated by accident, either. If a jilted ex murders the Prince of Placeland, it's just a murder. If a jilted ex is also a member of a rival political faction, it may be an assassination. If a jilted ex is driving home in tears and accidentally runs over the Prince of Placeland in the middle of the night in a neighborhood where the streetlights are out because of the prince's questionable infrastructure policy, it's manslaughter.