gation that began monitoring Schweitzer seminars in December of 1995. At the seminars, Schweitzer discussed the use of fraudulent checks to avoid the payment of debts and to obtain large refunds of “over-payments.” These “checks” contained the caption “Certified Banker’s Check” and/or “Comptroller Warrant” and bore the number of a Norwest Bank account. Persons attending a Freemen seminar received these checks after attending the meeting, usually after paying Schweitzer a donation. In addition, seminar attendees were taught to file a lien against those to whom the checks were presented in the event the checks were not honored. On July 21 and November 4, 1995, Mrs. Hanzlicek attended Freemen seminars in Montana presented by Schweitzer.
The government also introduced and played taped conversations between Mrs. Hanzlicek and Schweitzer. These recordings were the result of government wiretaps. The conversations included discussion about the checks, liens, and procedures Schweitzer wanted his classes to follow, the Freemen movement, and the “common law court” movement in Kansas.
III. ANALYSIS
A. Variance Between Indictment and Proof at Trial
Hanzlicek argues that an impermissible variance exists between the indictment, which alleged a single, overarching conspiracy, and the evidence adduced at trial, which demonstrated multiple independent conspiracies. To obtain a conspiracy conviction, the government must prove that: (1) there was an agreement to violate the law; (2) the defendants knew the essential objectives of the conspiracy; (3) the defendants knowingly and voluntarily participated in the conspiracy; and (4) interdependence existed among the coconspirators. See United States v. Ailsworth, 138 F.3d 843, 850 (10th Cir.), cert. denied, - U.S. -, 119 S.Ct. 221, 142 L.Ed.2d 181 (1998). These elements may be proven by direct or circumstantial evidence. See United States v. Evans, 970 F.2d 663, 668 (10th Cir.1992).
“A variance arises when the evidence adduced at trial establishes facts different from those alleged in an indictment.” See United States v. Edwards, 69 F.3d 419, 432 (10th Cir.1995). Any such variance is reversible error only if it affects the substantial rights of the accused. Ailsworth, 138 F.3d at 848. “Accordingly, where a single conspiracy is charged in the indictment, and the government proves only multiple conspiracies, a defendant who suffers substantial prejudice must have his conviction reversed.” Edwards, 69 F.3d at 432 (citing Kotteakos v. United States, 328 U.S. 750, 773-74, 66 S.Ct. 1239, 90 L.Ed. 1557 (1946)). A variance is prejudicial when guilt is imputed to one defendant from another defendant’s conduct. See Kotteakos, 328 U.S. at 775-77, 66 S.Ct. 1239.
The issue of whether a single conspiracy existed is a question of fact for the jury; this court reviews the jury’s decision on the question in the light most favorable to the government. See Edwards, 69 F.3d at 432. The inquiry focuses on whether the necessary interdependence existed between the coconspirators. See id. Interdependence exists when each alleged coconspirator’s activities “constituted essential and integral steps toward the realization of a common, illicit goal.” Id. (quotation omitted).
During the trial, evidence was admitted regarding not only the conspiracy as charged in the indictment, but additional conspiracies involving Schweitzer and others. Nevertheless, viewing the evidence in the light most favorable to the government, there was sufficient evidence to prove a single conspiracy. The admissible evidence at trial demonstrates an ongoing course of conduct between the Hanzliceks, Schweitzer, and others in order to achieve a common illicit goal — to profit from the fraudulent presentation of checks and the filing of liens. In addition, there was sufficient evidence, again viewed in the light most favorable to the government, to es