AI simulation system centered on Behavioral Fidelity, with speech interaction included as a design feature to enhance immersion. For standardization and reproducibility, the present pilot evaluation uses transcripts. The system integrates pragmatic–psychological rules with Taiwanese criminal case files to simulate witness behavior under cross-examination pressure. Using an optimized Expert Turing Test framework with four dimensions—professional accuracy, situational adaptability, human-likeness, and logical consistency—we conduct a pilot study. Under identical prompts and knowledge sources, the customized GPT condition received higher ratings than GPT-Vanilla on adaptability and human-likeness. Applying the same framework to another mainstream model (Gemini 2.5 Flash) yielded comparable performance, while differences remain inconclusive at this sample size. Overall, the results provide preliminary evidence that Behavioral Fidelity is a feasible evaluation target and indicate the scalability of generative AI for legal training; speech-condition evaluation and multi-case, multi-role extensions are left for future work.