Any competent Justice Department, reading supporting documentation for and granting wiretaps in regard to this operation should have known what was going on and when, and sent this information up the chain of command. Since the documents requested by congress have been blocked by the Obama White House, it appears clear that Holder knew but allowed the illegal activity to continue. It happened on his watch.
As with any employee "fired for cause", there should total denial of any and all benefits that might otherwise be granted should he be allowed to resign or retire on his own.
Given that President Obama claims no knowledge of the operation, Executive Privilege does not apply.