order to prove that a defendant committed the crime of conspiracy to possess narcotics with intent to distribute, the government must prove that (1) a conspiracy to possess narcotics with intent to distribute existed, (2) the defendant knew of the conspiracy, and (3) the defendant voluntarily participated in the conspiracy. United States v. Hernandez-Palacios, 838 F.2d 1346, 1348 (5th Cir.1988); see United States v. Cardenas, 9 F.3d 1139, 1157 (5th Cir.1993), cert. denied, — U.S. -, 114 S.Ct. 2150, 128 L.Ed.2d 876 (1994). No proof of an overt act is required. Hernandez-Palacios, 838 F.2d at 1348; Cacace v. United States, 590 F.2d 1339, 1340 (5th Cir.1979); United States v. Palacios, 556 F.2d 1359, 1364 n. 9 (5th Cir.1977). But see United States v. Shabani, 993 F.2d 1419 (9th Cir.1993) (<HOLDING>), cert. granted, — U.S. -, 114 S.Ct. 1047, 127
holding that proof of an overt act is not required in a  846 conspiracy holding that an 18 usc  1956h conspiracy does not require proof of an overt act holding that the elements of a drug conspiracy under 21 usc  846 do include an overt act requirement holding proof of an overt act is not required to establish a violation of  846 recognizing requirement that defendant conspired to commit an overt act in state in furtherance of the conspiracy