In presiding over a hearing conducted hereunder, the Deputy Labor Commissioner shall control the order of presentation of evidence at the hearing, and direct and rule on matters concerning the conduct of the hearing and of the parties appearing. Prior to a hearing, upon the application of any party to the proceedings, the Deputy Labor Commissioner may issue subpoenas to compel the attendance of necessary witnesses and the production of books and documents. In the exercise of his (her) sound discretion, the Deputy Labor Commissioner may limit the number of witnesses subpoenaed either for the purpose of corroboration or establishing a single material fact in issue, or where the party requesting the subpoena has not furnished satisfactory evidence that the witness will be able to give necessary and competent testimony, material to the issues, at the hearing.