You state the bare facts of which you are certain and let the higher-ups make the decisions. Don't get into details or make moral judgments. These two may both still be your supervisors at the end of it all. Best not to anger either one.
Tell as little as possible don't side with anyone don't get caught up in office politics or you will lose
i blame obama
in HR terms i'd call conflict, productive conflict.
Say a prayer. Do my best to remain calm. Tell the truth.