Is a prosecutor improperly vouching for the credibility of witnesses?

Defendant highlights seven transcript passages in which, he asserts, the prosecutor vouched for the credibility of his witnesses. As we held in People v. Frye (1998) 18 Cal.4th 894, 77 Cal.Rptr.2d 25, 959 P.2d 183 (Frye), "[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 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 prosecutors 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, [the prosecutors] comments cannot be characterized as improper vouching." (Id., at p. 971, 77 Cal.Rptr.2d 25, 959 P.2d 183, italics added.)

Defendant cites as misconduct (improper vouching) the following italicized passages of the prosecutor's comments to the jury: