The Secretary of State and the Attorney General, for the enforcement of both sections 76-1520 to 76-1524 and Article XII, section 8, of the Constitution of Nebraska, shall have the authority to subpoena witnesses, compel their attendance, examine them under oath, and require the production of documents, records, or tangible things deemed relevant to the proper performance of their duties. Service of any subpoena shall be made in the manner prescribed by the rules of civil procedure.