(1) The commissioner in his discretion may make such public or private investigations within or outside of this state as the commissioner deems necessary to determine whether any person has violated any provision of this article or any rule or order under this article or to aid in the enforcement of this article, or, in the prescribing of rules and forms under this article, the commissioner may require or permit any person to file a statement as to all the facts and circumstances concerning the matter to be investigated and may publish information concerning any proceeding brought under this article or any rule or order issued under this article.

(2) For purpose of any investigation or proceeding under thisarticle, the commissioner or any officer designated by the commissioner may administer oaths and affirmations, subpoena witnesses, compel their attendance, take evidence, and require the production of any books, papers, correspondence, memoranda, agreements, or other documents or records which the commissioner finds to be relevant or material to the inquiry.

(3) In case of contumacy by, or refusal to obey a subpoena issued to, any person, the district court of the city and county of Denver, upon application by the commissioner, may issue to such person an order requiring the person to appear before the commissioner, or the officer designated by him, to produce documentary evidence if so ordered or to give evidence touching the matter under investigation or in question. Failure to obey the order of the court may be punished by the court as a contempt of court.

(4) No person is excused from attending and testifying or from producing any document or record before the commissioner, or in obedience to the subpoena of the commissioner or any officer designated by the commissioner, or in any proceeding instituted by the commissioner on the ground that the testimony or evidence, documentary or otherwise, required of the person subpoenaed may tend to incriminate said person or subject the person to a penalty or forfeiture; but no document, evidence, or other information compelled under order of the district court of the city and county of Denver, or any information directly or indirectly derived from such document, evidence, or other information, may be used against an individual so compelled in any criminal case; except that the individual testifying is not exempt from prosecution and punishment for perjury in the first or second degree or contempt committed in testifying.