Does the government improperly vouch for the veracity of a witness testimony?

Preston further argues that the government impermissibly vouched for the veracity of Rosenberg's testimony. "Improper vouching consists of placing the prestige of the government behind a witness through personal assurances of the witness's veracity, or suggesting that information not presented to the jury supports the witness's testimony." United States v. Ruiz , 710 F.3d 1077, 1085 (9th Cir. 2013) (citation omitted).

Preston contends that the government offered personal assurances of Rosenberg's veracity in the following instances:

The defense objected only to the final comment. Although the court overruled

[873 F.3d 844]