Where's the Big Fish?

The man who deleted the emails from Clinton's private server, even after having been notified that the information was under a Congressional Subpoena, was granted immunity during the investigation.  Typically, one offers immunity to the little fish in order to nail the big fish.  So, where's the big fish?  The use of BleachBit sure does sound like it would prove the intent that FBI Director Comey said was lacking.  A conference call that involved the server company and Hillary's lawyers shortly before the server was wiped?  Hmm, sounds suspicious.  These lawyers are certainly bigger fish than the computer tech who bleached the emails.  Were they indicted?  No?  And now it turns out that the immunity deal is going to derail further investigation?  Oh, what an unfortunate turn of events!  Oops!  Looks like we screwed up and no one will be prosecuted for the destruction of government records.  Oh, that's a felony?  Huh.