(a) The district attorneys of the various counties shall have the power to enforce the provisions of this act, and, upon complaint of any person, or on his own initiative, to investigate any violation thereof, or to investigate the business, business practices and business methods of any person, partnership, association or corporation applying for or holding a license as a private detective or investigator if, in the opinion of the district attorney, such investigation is warranted. Each such applicant or licensee shall be obliged, on request of the district attorney, to supply such information as may be required concerning his or its business, business practices or business methods, or proposed business practices or methods.

(b) For the purpose of enforcing the provisions of this act and in making investigations relating to any violation thereof, and for the purpose of investigating the character, competency and integrity of the applicants or licensees hereunder, and for the purpose of investigating the business, business practices and business methods of any applicant or licensee, or of the officers or agents thereof, the district attorney, acting by such officer or person in the office of the district attorney as the district attorney may designate, shall have the power to subpoena and bring before the officer or person so designated any person in the county, and require the production of any books or papers which he deems relevant to the inquiry, and administer an oath to, and take testimony of, any person, or cause his deposition to be taken, with the same fees and mileage and in the same manner as prescribed by law for civil cases in a court of record, except that any applicant, or licensee, or officer, or agent thereof, shall not be entitled to such fees or mileage. Any person duly subpoenaed who fails to obey such subpoena without reasonable cause, or without such cause refuses to be examined or to answer any legal or pertinent question as to the character or qualification of such applicant or licensee or such applicant's or licensee's business, business practices and methods, or such violations, shall be guilty of a misdemeanor, and, upon conviction thereof, shall be sentenced to pay a fine of not more than five hundred dollars ($500) or to undergo imprisonment for not more than one (1) year, or both. The testimony of witnesses in any such proceeding shall be under oath, which the district attorney or his subordinate designated by the district attorney may administer, and wilful, false swearing in any such proceeding shall be punishable as perjury.