14 C.F.R. § 13.105 Notification.
Title 14 - Aeronautics and Space
Any person under investigation and any person required to testify and produce documentary or physical evidence during the investigation will be advised of the purpose of the investigation, and of the place where the investigative proceeding or deposition will be convened. This may be accomplished by a notice of investigation or by a subpoena. A copy of the order of investigation may be sent to such persons, when appropriate.
Title 14: Aeronautics and Space
PART 13—INVESTIGATIVE AND ENFORCEMENT PROCEDURES
Subpart F—Formal Fact-Finding Investigation Under an Order of Investigation
§ 13.105 Notification.