it is the jury’s function, not ours, to decide whether to return a guilty verdict in the first place.
724 F.2d at 856.
III. Sufficiency of the Evidence
Even fhonpb we re.verse for error in the Jewell instruction, double jeopardy concerns require us to reach Sanchez-Robles’s contention of insufficient evidence. See United States v. McKoy, 771 F.2d 1207, 1215 (9th Cir.1985). “[B]ecause an appellate reversal of a conviction on the basis of insufficiency has the same effect as a judgment of acquittal, the Double Jeopardy Clause would preclude retrial. [Therefore,] ‘the existence of other grounds for reversal does not avoid the necessity of reviewing the sufficiency of the evidence.’" Id. (quoting United States v. Bibbero, 749 F.2d 581, 586 (9th Cir.1984), cert. denied, 471 U.S. 1103, 105 S.Ct. 2330, 85 L.Ed.2d 847 (1985)).
At the conclusion of the government’s case in chief, Sanchez-Robles moved for a judgment of acquittal based on insufficiency of the government’s evidence, but she failed to renew her motion at the close of her case. A defendant who fails to renew such a motion has “effectively waived [her] objection to the sufficiency of the government’s evidence. In this circuit, however, we may review the denial of a non-renewed motion for acquittal, but only ‘to prevent a manifest miscarriage of justice.’ ” United States v. Comerford, 857 F.2d 1323, 1324 (9th Cir.1988) (citations omitted), cert. denied, 488 U.S. 1016, 109 S.Ct. 812, 102 L.Ed.2d 802 (1989).
Sanchez-Robles was the driver of the van and its sole adult occupant, not merely a passenger. See United States v. Murrieta-Bejarano, 552 F.2d 1323, 1324 (9th Cir.1977) (jury could infer that defendant knew of drugs because he was “driver and sole occupant” of truck containing them). The quantity of drugs in the van was enormous, the odor in the van was strong and Sanchez-Robles told her daughters not to say anything to customs officials. There was a can of hairspray in the van, which might have been used to mask the odor. A customs service vehicle report contradicted Guadalupe’s testimony of driving the car to Mexico and back that night, and evidence showed that Guadalupe’s boyfriend’s story of taking a bus and then a cab to the Sanchez-Robles apartment that night was untrue. Furthermore, there was circumstantial evidence that Sanchez-Robles had known Armando Lopez for longer than the one month she told customs officials. When viewed in the light most favorable to the government, it would not be a manifest miscarriage of justice for the jury to conclude that Sanchez-Robles knew the van contained illegal drugs when she drove it into the United States. The district court therefore properly denied Sanchez-Robles’s motion for acquittal. A retrial would not violate the double jeopardy clause.
IV. Prosecutorial Misconduct
Sanchez-Robles’s remaining claims of prosecutorial misconduct and errors in evi-dentiary rulings lack merit.
During redirect examination of a government agent at trial, the prosecution asked whether Sanchez-Robles’s private investigator had prevented the agent from speaking to Sanchez-Robles’s daughters when the agent visited their apartment. The court sustained Sanchez-Robles’s objection and later exonerated the private investigator in a hearing outside the presence of the jury. Sanchez-Robles argues that the improper question constitutes prosecutorial misconduct warranting a mistrial.
We review a motion for mistrial for abuse of discretion. United States v. Charmley, 764 F.2d 675, 677 (9th Cir.1985). “In assessing claims of prosecutorial misconduct, we must determine whether such misconduct occurred, whether the defendant properly preserved the issue for appeal, and whether the defendant was prejudiced by the misconduct.” United States v. Tham, 665 F.2d 855, 860 (9th Cir.1981) (citing United States v. Berry, 627 F.2d 193, 196-97 (9th Cir.1980), cert. denied, 449 U.S. 1113, 101 S.Ct. 925, 66 L.Ed.2d 843 (1981)), cert. denied, 456 U.S. 944, 102 S.Ct. 2010, 72 L.Ed.2d 466 (1982).