Can a prosecutor improperly vouch for the credibility of an expert witness?

"It is settled that '[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 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. Caldwell (2013) 212 Cal.App.4th 1262, 1269-1270.)

Here, the prosecutor's remarks were proper comment on the evidence. She discussed the credibility of her witnesses based on evidence in the record and the instructions provided by the court, without referring to personal beliefs, facts outside of the record, or the prestige of her office. She did not assert that the government's witnesses were entitled to any greater deference than any other witness. (Cf. People v. Turner (2004) 34 Cal.4th 406, 433 [prosecutor improperly vouched for the credibility of expert witness by referring to the prosecutor's personal knowledge of the witness and his prior use of the witness].) Instead, she referred the jury to the instructions given by the

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court and argued based on the facts in the record that her witnesses had testified truthfully.