That's why the last DOJ IG Report audited Comey, an FBI leader.
So what AG Barr is doing now is backwards -- he's claiming to audit the audit, disagreeing with DOJ's IG Report.
We still have to wait for a "full" investigation of the Russia investigation after this DOJ IG Investigation - the Durham investigation. Right now would be "premature" to make any judgment.
Barr is adding his own process, saying he appointed a prosecutor to separately investigate the investigation, but a US Atty probe would typically be for crimes, not a DOJ audit.