Does the testimony of a witness in a sexual assault case constitute an opinion on the truthfulness of another witness's testimony?

Nor did the investigators' statements amount to one witness offering an opinion on the truthfulness of another witnesses's testimony. Cf. United States v. Sanchez , 176 F.3d 1214, 1219 (9th Cir. 1999). The investigators were basically saying to Dubria: "If you stick to your version of what happened that night, not only will no one believe you, but you run the risk that they will impute motives to you that are far worse than you may have had." Especially in light of the two cautionary instructions given to the jury, it is very hard to characterize what the investigators told Dubria as a comment upon his truthfulness as a witness.