Levi has been retained as an expert witness to provide testimony for a trial.

The correct answer is A. The primary purpose of expert testimony is to help the fact finder understand the evidence or determine a fact in issue by applying specialized knowledge. Federal Rule of Evidence 702 states that an expert may testify when the expert’s scientific, technical, or other specialized knowledge will help the trier of fact understand the evidence or determine a fact in issue. That captures the classic role of an expert witness in fraud-related litigation.

Option B is incorrect because deciding the admissibility of evidence is generally a matter for the judge, not the expert witness. Option C is also incorrect because experts ordinarily are not called to opine on whether another witness is truthful; credibility determinations are for the fact finder. Option D is incorrect because experts generally do not decide or directly state whether the accused is guilty; that is the function of the judge or jury after considering all admissible evidence. In CFE practice, expert testimony is valuable because complex accounting records, financial analyses, loss calculations, and fraud patterns often require explanation beyond ordinary lay understanding. Therefore, the best statement of Levi’s primary purpose is that he will help the fact finder understand evidence through specialized knowledge, making A the correct answer.