What is the test for admitting an expert opinion in a criminal case?

Evidence Code section 801 provides in relevant part that "[i]f a witness is testifying as an expert, his testimony in the form of an opinion is limited to such an opinion as is: [] (a) Related to a subject that is sufficiently beyond common experience that the opinion of an expert would assist the trier of fact . . . ." Thus, "a witness cannot express an opinion concerning the guilt or innocence of the defendant. [Citations.]" (People v. Torres (1995) 33 Cal.App.4th 37, 46.) "[O]pinions on guilt or innocence are inadmissible because they are of no assistance to the trier of fact." (Id. at p. 47.) The same rationale that prohibits expert opinions on guilt "also prohibits the witness from expressing an opinion as to whether a crime has been

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committed." (Ibid.) We review for abuse of discretion whether the trial court erred in admitting testimony. (See People v. Prince (2007) 40 Cal.4th 1179, 1223.)