Is a prosecutor permitted to vouch for the credibility of witnesses by referring to evidence that is not in the record?

" '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. [Citation.] Nor is a prosecutor permitted to place the prestige of her office behind a witness by offering the impression that she 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," her comments cannot be characterized as improper vouching.' " (People v. Ward (2005) 36 Cal.4th 186, 215.)