What is the test for good faith and due diligence in the prosecution of a sexual assault case?

In the last analysis, " ' "[t]he lengths to which the prosecution must go to produce a witness . . . is a question of reasonableness.["] [Citation.] The ultimate question is whether the witness is unavailable despite good-faith efforts undertaken prior to trial to locate and present that witness.' [Citations.]" (People v. Herrera (2010) 49 Cal.4th 613, 622.) We review the trial court's resolution of disputed factual matters under the substantial evidence standard, but independently review whether the facts amount to good faith and due diligence on the part of the prosecutor. (Ibid.)

2. Factual Background