Well, there were documents part of the Snowden leaks that showed how some NSA agents used the agency's tools to spy on (former) romantic partners and such, and I think he said something along the lines of this kind of thing not being prosecuted much. Sure, it's still a different level than a political case like this one, but it does call the internal oversight at the NSA into question.

If I was the director of the CIA I'd cover up any internal corruption, to avoid being subject to additional oversight or public criticism. We've already banked the public trust from having audit records exist, actually checking the audit records can only reveal bad news.

That's the point of a Congressional summons and testimony.

You can cover up things quietly, but lying to Congress when asked about it carries a very different set of penalties.

But lying to Congress is kind of a moving target. You can get away with it if you later when found out come back in with a "I was misinformed" or "I misunderstood the question" performance.