Under 18 U.S.C. § 1751(i), the Federal Bureau of Investigation (FBI) has lead responsibility for the investigation of violations of § 1751. This section does not diminish the existing authority and responsibility of the Secret Service for the protection of the President or for making arrests for violation of the statute. Thus, the Secret Service will continue to investigate all threats against the President (18 U.S.C. § 871), but the FBI will investigate all types of assaults and all actual kidnappings and killings. In addition, the FBI will investigate conspiracies and attempts to kill or kidnap the President.
There is an "Agreement of Procedures" between the Secret Service and the FBI regarding the transfer of responsibility in the event of the killing of a Secret Service protectee or any other violation of law involving a Secret Service protectee for which the FBI has investigative jurisdiction. As of July 1996, the 1978 agreement remains in effect; see this Manual at 1527. However, contact should be made with the Terrorism and Violent Crime Section of the Criminal Division (TVCS), (202) 514-0849, to verify the current procedures.
[cited in USAM 9-65.300]