After August 1, 1914, any officer or employee appointed or designated by the Secretary of the Interior or the Commissioner of Indian Affairs as special examiner in heirship cases shall be authorized to administer oaths in investigations committed to him: Provided further, That the provisions of this paragraph shall not apply to the Osage Indians nor to the Five Civilized Tribes of Indians in Oklahoma.
25 U.S. Code § 376 - Oaths in investigations
For transfer of functions of other officers, employees, and agencies of Department of the Interior, with certain exceptions, to Secretary of the Interior, with power to delegate, see Reorg. Plan No. 3 of 1950, §§ 1, 2, eff. May 24, 1950, 15 F.R. 3174, 64 Stat. 1262, set out in the Appendix to Title 5, Government Organization and Employees.