On the judge's own motion, or the motion of any party, the administrative law judge may omit oral presentation of the direct testimony of any witness and may allow prefiled written testimony to be presented in its place. The written testimony carries the same force and effect as though stated orally by the witness; provided that the witness must be present at the hearing at which such testimony is offered and adopt such testimony under oath, and must be made available for cross-examination. Written reports of agency investigations on fact issues, if offered into evidence in a hearing in which the facts covered by the report are directly at issue, will be treated as prefiled testimony and the investigator must be made available for cross-examination unless the investigator is unavailable to the agency as a witness or unless the report comes into evidence without objection. If the investigator is unavailable to the agency as a witness, the report shall be admissible under Rule 803, Texas Rules of Evidence if it meets the requirements for admission into evidence under that rule. For purposes of this section "unavailability as a witness" has the same meaning as in Rule 804(a), Texas Rules of Evidence.