What is the sufficiency of the evidence challenge regarding a charge of conspiracy to murder?

For a conspiracy charge to withstand a sufficiency of the evidence challenge, "[t]he record must ... permit a rational jury to find: (1) the existence of the conspiracy charged; (2) that the defendant had knowledge of the conspiracy; and (3) that the defendant intentionally joined the conspiracy." United States v. Santos, 541 F.3d 63, 70 (2d Cir. 2008) cert denied 555 U.S. 1122 (2009) (citations omitted). In Santos, we considered a similar sufficiency of the evidence challenge regarding a 21 U.S.C. 848(e)(1)(A) conviction, and concluded that the statute had two elements: "one drug offense and one killing." Santos, 541 F.3d at 69. As to the independent drug offense, the relevant drug conspiracy statute does not require an overt act. Id. at 68. Accordingly, "the conspiracy itselfand no act in furtherance of it, homicidal or otherwiseserves as the predicate drug offense under section 848(e)(1)(A)." Id.