The commission shall provide itself with a proper seal and shall have the power and authority to issue subpoenas and to compel the attendance of witnesses and parties and to compel the production of relevant books, correspondence, files, records, and accounts of any person, corporation, association, or labor organization affected, and to make any and all investigations necessary to ascertain the truth in regard to the matters before the commission. Subpoenas for the production of books, correspondence, files, records and accounts shall be issued by the commission only after notice to the owner and person in possession thereof and opportunity to be heard as to the relevancy of such subpoena.