For the purpose of hearings before the board, the board shall have power to administer oaths and affirmations and to issue subpoenas requiring the attendance of witnesses. In case of contumacy or refusal to obey a subpoena issued to any person, the Superior Court, upon application by the board, shall have jurisdiction to order such person to appear before the board to produce evidence or to give testimony touching the matter under investigation or in question, and any failure to obey such order may be punished by said court as a contempt thereof. No person shall be excused from attending and testifying or from producing books, records, correspondence, documents or other evidence in obedience to the subpoena of the board, on the ground that the testimony or evidence required of him may tend to incriminate him or subject him to a penalty or forfeiture; but no individual shall be prosecuted or subjected to any penalty or forfeiture for or on account of any transaction, matter or thing concerning which he is compelled, after having claimed his privilege against self-incrimination, to testify or produce evidence, except that such individual so testifying shall not be exempt from prosecution and punishment for perjury committed in so testifying. Complaints, orders and other processes and papers of the board or the agent may be served personally, by registered or certified mail, by telegraph or by leaving a copy thereof at the principal office or place of business of the person required to be served. The verified return of service shall be proof of such service. Witnesses summoned before the board or the agent shall be paid the same fees and mileage allowances that are paid witnesses in the courts of this state, and witnesses whose depositions are taken and the person taking the same shall severally be entitled to the same fees as are paid for like services in the courts of this state. All processes of any court to which an application or petition may be made under this chapter may be served in the judicial district wherein the person or persons required to be served reside or may be found.