Is a prosecutor permitted to vouch for the credibility of witnesses?

"[A] prosecutor is free to give his opinion on the state of the evidence, and in arguing his case to the jury, has wide latitude to comment on both its quality and the credibility of witnesses." (People v. Padilla (1995) 11 Cal.4th 891, 945-946 (Padilla), overruled on another ground in Hill, supra, 17 Cal.4th at p. 823, fn. 1.) However, "[a] prosecutor is prohibited from vouching for the credibility of witnesses or otherwise bolstering the veracity of their testimony by referring to evidence outside the record. [Citations.] Nor is a prosecutor permitted to place the prestige of [his] office behind a witness by offering the impression that [he] has taken steps to assure a witness's truthfulness at trial. [Citation.] However, so long as a prosecutor's assurances regarding the apparent honesty or reliability of prosecution witnesses are based on the 'facts of [the] record and the inferences reasonably drawn therefrom, rather than any purported personal knowledge or belief,' [his] comments cannot be characterized as improper vouching."

Page 32