After the conclusion of a hearing but prior to the making of an order by the Attorney General, a hearing may, upon petition and in the discretion of the hearing officer, be reopened for the presentation of new evidence. Such petition to reopen the hearing shall state in detail the nature of the new evidence, together with the reasons for the failure to submit such evidence prior to the conclusion of the hearing. The hearing officer may upon his own motion and upon reasonable notice to the parties reopen a hearing for the presentation of additional evidence.