Trial court erred by not holding evidentiary hearing on defense motion to recuse prosecutor where the resolution of significant factual disputes in the defense’s favor could require recusal. Packer was charged with multiple counts of first degree murder in a capital case. He filed a motion to recuse the lead prosecutor, Frawley, for an alleged conflict of interest. (Pen. Code, § 1424.) The motion was based on numerous grounds, including that Frawley had actively interfered with the defense’s efforts to contact his children and their friends (who knew Packer) and that he had a personal interest in not having his children testify at Packer’s penalty phase. The trial court denied the motion without an evidentiary hearing. Packer’s petition for writ of mandate was denied by the Court of Appeal. The Supreme Court granted review. Held: Reversed with directions to issue writ of mandate. Penal Code section 1424 creates a two-step process by which a defendant may seek to recuse a prosecutor for an alleged conflict of interest that would render a fair trial unlikely. At the first stage, the defense must file a recusal motion that sets forth the facts of the alleged conflict, which must be supported by witness affidavits. In opposition to the motion, the prosecution may also file affidavits. Based on the written motions, the court decides whether the second stage, an evidentiary hearing, is necessary. Here, a hearing was required on the issue of whether Frawley had become so personally involved in the case so as to render it unlikely that Packer would receive fair treatment during his trial. The trial court did not resolve factual disputes raised by the parties’ affidavits and failed to make any credibility findings concerning the disputes. If the facts were resolved in Packer’s favor, they would support his claim that Frawley actively interfered with the defense’s pretrial investigation into penalty phase evidence, which would be a genuine disabling conflict.