Is a prosecutor permitted to place the prestige of his office behind a witness?

record. [Citations.] Nor is a prosecutor permitted to place the prestige of [his or] her office behind a witness by offering the impression that [he or] 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,' [his or] her comments cannot be characterized as improper vouching." (People v. Frye (1998) 18 Cal.4th 894, 971.)