43 U.S.C. § 1466

Special agents and such other employees of the Division of Investigations, Department of the Interior of the United States, as are designated by the Secretary of the Interior for that purpose, are authorized and empowered to administer to or take from any person an oath, affirmation, affidavit, or deposition whenever necessary in the performance of their official duties. Any such oath, affirmation, affidavit, or deposition administered or taken by or before a special agent or such other employee of the Division of Investigations, Department of the Interior, designated by the Secretary of the Interior, when certified under his hand, shall have like force and effect as if administered or taken before an officer having a seal.