Does a defendant need to know that the relevant officer is a federal investigator?

¹¹ See, e.g., United States v. Grande , 620 F.2d 1026, 103637 (4th Cir. 1980) (holding that 18 U.S.C. 1510, which criminalizes obstruction of a criminal investigation, requires that the defendant know that the relevant officer was a "federal criminal investigator" based on legislative history indicating that "if a person does not know that the investigator is a federal investigator, an act which would normally be in violation would not be so because of the lack of the scienter as to the identity of the investigator" (quoting H.R. Rep. No. 90-658 (1967), as reprinted in 1967 U.S.C.C.A.N. 1760, 1762)).