What is the burden of proving a defendant has been convicted of a serious or violent felony for purposes of section 667 of the California Criminal Code?

Where, as here, a criminal information or complaint alleges the defendant was previously convicted of a serious or violent felony for purposes of section 667, the prosecution is required to prove each element of an alleged sentence enhancement beyond a reasonable doubt. (People v. Delgado (2008) 43 Cal.4th 1059, 1065.) "[I]f the prosecutor presents, by [certified criminal] records, prima facie evidence of a prior conviction that satisfies the elements of the recidivist enhancement at issue, and if there is no contrary evidence, the fact finder, utilizing the official duty presumption, may determine that a qualifying conviction occurred. [Citations.] [] However, if the prior conviction was for an offense that can be committed in multiple ways, and the record of the conviction does not disclose how the offense was committed, a court must presume the conviction was for the least serious form of the offense. [Citations.] In such a case, if the statute under which the prior conviction occurred could be violated in a way that does not qualify for the alleged enhancement, the evidence is thus insufficient, and the People have failed in their burden. [Citations.]" (Id. at p. 1066.)