Is there any case law where a defendant was an organizer or leader of a criminal activity that involved five or more participants or was otherwise extensive?

Section 3B1.1(a) of the Guidelines provides for a four-level increase in the base offense level where "the defendant was an organizer or leader of a criminal activity that involved five or more participants or was otherwise extensive." U.S.S.G. 3B1.1(a). Section 3B1.1(a) does not require a defendant to supervise personally each participant. United States v. Smith, 924 F.2d 889, 896 (9th Cir.1991). A participant is any person who is criminally responsible for the offense even if not convicted. Id. We review the district court's determination that Sanders was an organizer or leader of five or more people for clear error. United States v. Carvajal, 905 F.2d 1292, 1295 (9th Cir.1990).