I believe U.S Attorney John Huber, who is investigating the FBI's actions during the campaign has subpoena power, and authority to recommend criminal charges.
That’s not what Sessions said in his March 29 letter to Grassley describing John Huber’s role.
He said Huber is “leading an effort” to “evaluate certain issues previously raised” by Grassley’s committee.
He described Huber as conducting a “review” and that Sessions would consider whether a Special Counsel should be appointed to conduct a criminal investigation “at the conclusion of his review.”
There is absolutely zero reason from Sessions’ description of the role he gave Huber to believe Huber has been authorized to empanel a grand jury or has been assigned FBI agents to actually collect evidence in a criminal investigation.
It seems clear Huber is merely conducting a “review” to “evaluate issues” and maybe later Sessions will allow a criminal investigation after hearing the results of Huber’s “review.”