could have found that he signed the returns willfully and knowing that they were false, and sufficient evidence supported the jury's verdict.

3. Due Process Based on Successive Prosecutions
Presbitero also argues that he was deprived of his right to the due process of law when the government prosecuted him *702 in this case after unsuccessfully charging and trying
him with ERISA and mail fraud violations in an earlier case because, he says, the government took inconsistent positions in the two cases. The indictment in the earlier case charged that Presbitero and Presbitero Drywall Company underreported the total hours worked by drywall installers and the total fringe benefit contributions due for PDC from January 1995 through August 1997, thereby defrauding a carpenters' trust fund and causing false reports to be filedraise his prior acquittal for bias purposes while Special Agent Seltzer was on the stand.
Special Agent Seltzer testified about summaries she prepared of the 800 or so checks PDC made out to the six subcontractors. She also testified that computer searches she ran yielded no evidence that the six subcontractors existed other than their incorporation in 1993 and dissolution in 1994. During her testimony, she also said there were no seasonal fluctuations in the value of checks cashed each week and that it was unusual for a business to cash checks at a currency exchange, for which a fee must be paid, instead of depositing them into a corporate checking account.
Presbitero argues on appeal that Special Agent Seltzer was biased because Presbitero was acquitted in the earlier case