When a defendant who has been acquitted of an offense petitions for a finding of factual innocence, what is the burden of proof?

When a defendant who has been acquitted of an offense petitions for a finding of factual innocence, the trial court "holds a hearing at which 'the initial burden of proof shall rest with the petitioner to show that no reasonable cause exists to believe that the [defendant] committed the offense [charged]. If the court finds that this showing of no reasonable cause has been made by the petitioner, then the burden of proof shall shift to the respondent to show that a reasonable cause exists to believe that the petitioner committed the offense [charged].' ( 851.8, subd. (b) . . . .)" (People v. Adair (2003) 29 Cal.4th 895, 902-903 (Adair), brackets in original, fn. omitted.)