What is the critical inquiry in determining the sufficiency of evidence to support criminal conviction?

When reviewing the sufficiency of the evidence to support a criminal conviction, the critical inquiry is whether, "after viewing the evidence in the light most favorable to the prosecution, any rational trier of fact could have found the essential elements of the crime beyond a reasonable doubt." Jackson v. Virginia, 443 U.S. 307, 319, 99 S.Ct. 2781, 2789, 61 L.Ed.2d 560 (1979) (emphasis in original).

We must determine whether the trier of fact could reasonably arrive at its conclusion. All reasonable inferences must be drawn in favor of the government, and circumstantial evidence is sufficient to sustain a conviction. United States v. Fleishman, 684 F.2d 1329, 1340 (9th Cir.1982), cert. denied, --- U.S. ----, 103 S.Ct. 464, 74 L.Ed.2d 614 (1982).

In reviewing the sufficiency of the evidence, we must first determine whether the charged conspiracy was proved.