Can an attorney argue that defense witnesses with ties to the charter school movement are biased?

Defendants claim that the People deviated from the single course-of-conduct theory during rebuttal argument, thereby rendering a unanimity instruction necessary. In support, they point to four comments, three of which suggested that defense witnesses with ties to the charter school movement were biased. We are not persuaded. An attorney is permitted "to remind the jurors that a paid witness may accordingly be biased and is also allowed to argue, from the evidence, that a witness's testimony is unbelievable, unsound, or even a patent 'lie.'" (People v. Arias (1996) 13 Cal.4th 92, 162.) In attempting to characterize defense witnesses as biased, the People were asking the jurors to reject their testimony, not presenting multiple arguments as to why the credit card charges constituted embezzlement.