What is the standard of review in a case wherein the district court has ruled whether a private citizen was acting as an agent of the government for fourth amendment purposes?

Neither party has cited any case law dealing with the applicable standard of review in a case wherein the district court has ruled whether a private citizen was acting as an "agent" of the government for fourth amendment purposes. A district judge's findings of fact in a suppression hearing are subject to the "clearly erroneous" standard. See, e. g., United States v. Botero, 589 F.2d 430, 433 (9th Cir. 1978), cert. denied, 441 U.S. 944, 99 S.Ct. 2162, 60 L.Ed.2d 1045 (1979). Because we find that the district court's ruling was proper under any standard, we decline to announce a definite standard for findings that a private citizen has acted as an "agent" of the government here.