What is the test for making a threat against a person?

18 U.S.C. Sec. 1513(a)(2). In a prosecution for such threats, "whether the statements made and acts engaged in amount to threatening conduct is a question of fact for the jury." United States v. Paradis, 802 F.2d 553, 563 (1st Cir.1986); see also United States v. Carrier, 672 F.2d 300, 306 (2d Cir.) (in prosecution under 18 U.S.C. Sec. 871 for threat against President of the United States, "whether words used are a true threat is generally best left to the triers of fact"), cert. denied, 457 U.S. 1139, 102 S.Ct. 2972, 73 L.Ed.2d 1359 (1982).