The Attorney General shall, when required by the public service or when directed by the Governor, in writing, repair in person, or by any regular or specially designated assistant, to any county or district in the state and assist the district attorney there in the discharge of his duties and in any prosecution against a state officer, and shall have the same right as the district attorney to enter the grand jury room while the grand jury is in session and to perform such services with reference to the work of the grand jury as the district attorney is authorized by law to perform.