Under Penal Code section 995, an information must be set aside if the defendant has been committed without "reasonable or probable cause." (Pen. Code, 995, subd. (a)(2)(B).) The magistrate must be convinced of a state of facts that would lead a person "of ordinary caution or prudence to believe, and conscientiously entertain a strong suspicion of the guilt of the accused." (Taylor v. Superior Court (1970) 3 Cal.3d 578, 582, overruled on another ground in People v. Antick (1975) 15 Cal.3d 79, 92, fn. 12.) "It is the magistrate who is the finder of fact; the superior court has none of the foregoing powers, and sits merely as a reviewing court; it must draw every legitimate inference in favor of the information, and cannot substitute its judgment as to the credibility or weight of the evidence for that of the magistrate. On review by appeal . . . the appellate court in effect disregards the ruling of the superior court and directly reviews the determination of the magistrate holding the defendant to answer," which must be upheld if it is supported by substantial evidence. (People v. Laiwa (1983) 34 Cal.3d 711, 718.)