In United States v. Lemm, 680 F.2d 1193, 1199 (8th Cir. 1992), the defendants perpetrated an insurance fraud scheme involving some seventeen arson fires in five states over a three-year period. The court found a common purpose where each of the defendants shared with the others the purpose of setting arson fires so as to defraud insurance companies, and all of them carried out this purpose through their participation in the acts. See id.