The answer is no, we don't operate that way. We don't do surprise visits.
I can tell you that in the course of doing some investigations, there are always cross-references. In other words, it's not just in one place. When information is exchanged or communications are exchanged, there's a sender and a receiver, and typically the information shows up in different places.
So to erase something from the files would be very difficult, because it may be in many different areas. It may have been copied to a number of people. Obviously there are ways in which we can keep on top of this and assure ourselves that nothing is being hidden from us or has been purposely destroyed. Our researchers, analysts, and investigators are very good at what they do, and we have every reason to believe that this kind of thing doesn't happen.