The Director, Associate Director, Assistant to the Director, Assistant Directors, inspectors, and agents of the Federal Bureau of Investigation of the Department of Justice may carry firearms, serve warrants and subpoenas issued under the authority of the United States and make arrests without warrant for any offense against the United States committed in their presence, or for any felony cognizable under the laws of the United States if they have reasonable grounds to believe that the person to be arrested has committed or is committing such felony.
18 U.S. Code § 3052 - Powers of Federal Bureau of Investigation
Language relating to seizures under warrant is in section 3107 of this title.
Minor changes were made in phraseology particularly with respect to omission of provision covered by rule 5(a) of Federal Rules of Criminal Procedure.
1951—Act Jan. 10, 1951, allowed F. B. I. personnel to make arrests without a warrant for any offense against the United States committed in their presence.
Functions of all other officers of Department of Justice and functions of all agencies and employees of such Department, with a few exceptions, transferred to Attorney General, with power vested in him to authorize their performance or performance of any of his functions by any of such officers, agencies, and employees, by Reorg. Plan No. 2 of 1950, §§ 1, 2, eff. May 24, 1950, 15 F.R. 3173, 64 Stat. 1261, set out in the Appendix to Title 5, Government Organization and Employees.