IIRC, at the time of Watergate there was a law allowing the an independent prosecuter completely outside the control of the AG to be appointed. After the special prosecutor (Cox) under Attorney General Elliot L. Richardson was sacked, and later Leon Jaworski was appointed under that act. It expired back in the 90’s and was not renewed. Now the only person who can appoint a prosector is Holder, and he no longer is truley independent; he serves at the pleasure of the AG who can remove him at will.
Good luck at getting Holder to appoint one.