(a)(1) At any time after the initiation of the proceeding, the hearing officer may order, by subpoena if necessary, the taking of a deposition and the production of relevant documents by the deponent. Such order may be entered upon a showing that the deposition is necessary for discovery purposes, and that such discovery could not be accomplished by voluntary methods. Such an order may also be entered in extraordinary circumstances to preserve relevant evidence upon a showing that there is substantial reason to believe that such evidence could not be presented through a witness at the hearing. The decisive factors for a determination under this subsection, however, shall be fairness to all parties and the requirements of due process. Depositions may be taken orally or upon written questions before any person who has the power to administer oaths.(2) Each deponent shall be duly sworn, and any adverse party shall have the right to cross-examine. Objections to questions or documents shall be in short form, stating the grounds upon which objections are made. The questions propounded and the answers thereto, together with all objections made (but not including argument or debate), shall be reduced to writing and certified by the officer before whom the deposition was taken. Thereafter, the officer shall forward the deposition and one (1) copy thereof to the party at whose instance the deposition was taken and shall forward one (1) copy to the representative of the other party.(3) A deposition may be admitted into evidence as against any party who was present or represented at the taking of the deposition, or who had due notice thereof, if the hearing officer finds that there are sufficient reasons for admission and that the admission of the evidence would be fair to all parties and comport with the requirements of due process.(b)(1) At any time after the initiation of the appeal, any party may serve upon any other party written interrogatories to be answered by the party served, or by an authorized representative of the party if the party served is a corporate or governmental entity. The party served shall furnish all information which is available to it.(2) Each interrogatory shall be answered separately and fully in writing under oath by the party addressed or by an authorized representative. The time and manner of returning the interrogatory shall be prescribed by the hearing officer.