What is the test for a jury to convict two defendants of conspiracy to pervert the course of justice?

Finally, both defendants contend that the evidence was insufficient to support their convictions. Specifically, they contend that the evidence was insufficient for the jury to have found that they knowingly participated in the conspiracy and that the conspiracy was in existence during the statute of limitations period. In reviewing these claims, we "must examine the evidence in the light most favorable to the government and determine whether any rational trier of fact could have found the essential elements of the offense beyond a reasonable doubt." United States v. Little, 753 F.2d 1420, 1449 (9th Cir.1984) (citing Jackson v. Virginia, 443 U.S. 307, 319, 99 S.Ct. 2781, 2789, 61 L.Ed.2d 560 (1979)).