Don't know what their official title would be, but I'd imagine that most ordinary people would tend to just call them their bodyguard.
LabRat
Athos: If you'd told us what you were doing, we might have been able to plan this properly. Aramis: Yes, sorry. Athos: No, no, by all means, let's keep things suicidal.
If they were in the Federal Witness Protection program, that is administered by the U.S. Marshals Service, so they would either be dealing with the Case Agent for the agency that had them entered into the program (for everything dealing with the ongoing investigation), or with a Deputy U.S. Marshal.
If they were in the Federal Witness Protection program, that is administered by the U.S. Marshals Service, so they would either be dealing with the Case Agent for the agency that had them entered into the program (for everything dealing with the ongoing investigation), or with a Deputy U.S. Marshal.