(a) The commissioner may examine the books, papers and records of any company or municipal utility in order to verify the accuracy of any return made or, if no return is made by the company or municipal utility, to ascertain and determine the amount required to be paid.

(b) The commissioner and any agent of the commissioner authorized by him to conduct any inquiry, investigation or hearing under chapter 210, 211 or 212 or this chapter may administer oaths and take testimony under oath relative to the matter of inquiry or investigation. At any hearing ordered by the commissioner, the commissioner or his agent authorized to conduct such hearing may subpoena witnesses and require the production of books, papers and documents pertinent to such inquiry. No witness under subpoena as aforesaid shall be excused from testifying or from producing books or papers on the ground that such testimony or the production of such books or other documentary evidence would tend to incriminate him, but such evidence or the books or papers so produced shall not be used in any criminal proceeding against him. If any person disobeys such process or, having appeared in obedience thereto, refuses to answer any pertinent question put to him by the commissioner or his authorized agent, or to produce any books and papers pursuant thereto, the commissioner or such agent may apply to the superior court for the judicial district wherein such person resides or wherein the business under investigation has been conducted, or to any judge of said court if the same is not in session, setting forth such disobedience to process or refusal to answer, and said court or such judge shall cite such person to appear before said court or such judge to answer such question or to produce such books and papers and, upon his refusal so to do, shall commit such person to a community correctional center until he testifies, but not for a longer period than sixty days. Notwithstanding the serving of the term of such commitment by any person, the commissioner may proceed in all respects with such inquiry and examination as if the witness had not previously been called upon to testify. Officers who serve subpoenas issued by the commissioner or under his authority and witnesses attending hearings conducted by him hereunder shall receive fees and compensation at the same rates as officers and witnesses in the courts of this state, to be paid on vouchers of the commissioner on order of the Comptroller from the proper appropriation for the administration of this chapter.