Holder is obviously a student of Obama's management strategy which I call "selective ignorance". The intentionally stays out of the loop and when the crises breaks he can honestly claim ignorance and use his amazing spin talent to side step the problem. This strategy allows his staff to operate independently counting on him and his media relationship to spin out of any problem with minimal damage.
He does not give orders. He provides a leadership image and allows subordinates to act on their own.
Stop asking what he knew and when he knew it, ask him why he does not know!