It is rather important to review the Rosenstein's letter appointing the special investigation by Mueller...............Here are some excerpts:
The Special Counsel is authorized to conduct the investigation confirmed by then-FBI Director James B. Comey in testimony before the House Permanent Select Committee on Intelligence on March 20, 2017
(i) any links and/or coordination between the Russian government and individuals associated with the campaign of President Donald Trump; and
(ii) any matters that arose or may arise directly from the investigation; and
(iii)
any other matters within the scope of 28 C.F.R. § 600.4(a).
(i) and (ii) are pretty banal. However, (iii) is interesting because it is also mentioned later in the document. Reading the relevant section of the CFR:
www.law.cornell.edu/…
(c) If the Special Counsel believes it is necessary and appropriate, the Special Counsel is authorized to prosecute federal crimes arising from the investigation of these matters.
§ 600.6 Powers and authority.
Subject to the limitations in the following paragraphs, the Special Counsel shall exercise, within the scope of his or her jurisdiction, the full power and independent authority to exercise all investigative and prosecutorial functions of any United States Attorney. Except as provided in this part, the Special Counsel shall determine whether and to what extent to inform or consult with the Attorney General or others within the Department about the conduct of his or her duties and responsibilities.
