In People v. Friend (2009) 47 Cal.4th 1, 67-68, the California Supreme Court restated the constitutional and statutory principles governing the admissibility of an unavailable witness's former testimony at trial: "'A criminal defendant has the right under both the federal and state Constitutions to confront the witnesses against him or her. This right, however, is not absolute. The high court . . . reaffirmed the long-standing exception that "testimonial statements of witnesses absent from trial have been admitted only where the declarant is unavailable, and only where the defendant has had a prior opportunity to cross examine."' 'Evidence Code section 1291 codifies this traditional exception.' 'When the requirements of Evidence Code section 1291 are met, "admitting former testimony in evidence does not violate a defendant's right of confrontation under the federal Constitution."' 'Evidence Code section 1291, subdivision (a)(2), provides that former testimony is not rendered inadmissible as hearsay if the declarant is "unavailable as a witness," and "the party against whom the former testimony is offered was a party to the action or proceeding in which the testimony was given and had the right and opportunity to cross-examine the declarant with an interest and motive similar to that which he has at the hearing." . . . Evidence Code section 240, subdivision (a)(5), states a declarant is "unavailable as a witness" if he or she is "absent from the hearing and the proponent of his or her statement has exercised reasonable diligence but has been unable to procure his or her attendance by the court's process."'" The Supreme Court further stated: "'The term "reasonable diligence" or "due diligence" under Evidence Code section 240, subdivision (a)(5) "'connotes persevering application, untiring efforts in good earnest, efforts of a substantial character. '"' 'Considerations relevant to this inquiry include the timeliness of the search, the importance of the proffered testimony, and whether leads of the witness's possible location were competently explored.' Citation. 'We independently review a trial court's due diligence determination.'" (People v. Friend, supra, 47 Cal.4th at pp. 68-69.)