“For what purpose? “
Good question. I know it exists, but don’t know the purpose.
5.56mm
A US Attorney investigates a thousand or so cases per year. A Utah grand jury need not have anything to do with the 2016 campaign.
Grand jury witnesses are not bound to secrecy, so high-profile, politically-connected grand jury investigations always become known.
Upthread, there are links to Huber’s assigned tasks, none of which are prosecutions.