As the majority frames the issue, this case requires that we consider what prosecutorial efforts will sustain a finding of unavailability when the absent witness was not in this jurisdiction but in another country. (Maj. opn., ante, at p. 623.) The majority concludes that if evidence supports the trial court’s finding that the witness was out of the country and in a country with which no treaty exists for the production of witnesses for trials in the United States, the prosecution has “fulfilled its obligation of good faith and due diligence” (id. at p. 629) in demonstrating the witness’s unavailability; consequently, the trial court properly admitted Portillo’s preliminary hearing testimony (ibid.; see also id. at p. 632). I concur that the trial court properly admitted Portillo’s preliminary hearing testimony at defendant’s trial. I do so, however, not on grounds the prosecution exercised due diligence, but on grounds of harmless error; as the *633majority states, “even assuming the prosecution should have started its search weeks earlier, further efforts to locate Portillo in California would have been futile . . . {Id. at p. 630.)
The facts of this case are analogous to a situation in which the prosecution is unjustifiably late in beginning its search for a witness, but then discovers the witness died several months earlier. In that situation, even had the prosecution commenced its search in a timely manner, the result would be the same. Hence, any dereliction of the prosecution’s duty to exercise due diligence to procure the witness’s attendance at trial would be harmless.
The same is true here. Evidence showed Portillo had been deported to El Salvador eight months before trial. The prosecution did not begin looking for him until the last court day before the trial was scheduled to begin. But even had the prosecution begun its search several days or weeks earlier, it would merely have discovered Portillo was out of the country and immune from the court’s process. In short, even had the prosecution been reasonably diligent, the result would have been the same.
Although I thus agree with the majority’s decision to reverse the Court of Appeal’s contrary ruling, I do not join that part of its analysis that concludes the prosecution satisfied its obligation of exercising due diligence in seeking to locate Portillo. As the majority relates, trial was scheduled for March 7, 2007, but was continued two months to May 21 because neither side was ready. On and after May 21 the trial was trailed three times, but by Friday, May 25, it was fairly certain the trial would commence on the next court day, Tuesday, May 29. Only then did investigator Wood begin to search for Portillo. “We have said that the term ‘due diligence’ is ‘incapable of a mechanical definition,’ but it ‘connotes persevering application, untiring efforts in good earnest, efforts of a substantial character. ’ ” (People v. Cromer (2001) 24 Cal.4th 889, 904 [103 Cal.Rptr.2d 23, 15 P.3d 243], italics added.) In measuring the prosecution’s diligence, the timeliness of the search and the importance of the witness’s proffered testimony are important factors. {Ibid.)
In my view, the prosecution’s belated efforts to locate Portillo—its star witness—do not satisfy this rigorous standard. Rather, in finding good faith and due diligence, the majority seems to be assessing the prosecution’s efforts in hindsight; that is, because ultimately the evidence showed any reasonable efforts to locate Portillo would have been futile, the majority concludes the prosecution’s efforts, however meager, were sufficient. But harmless error is not due diligence.
*634In light of the overall importance of the right to confront adverse witnesses, I cannot join the majority’s holding that the prosecution’s efforts in this case demonstrated good faith and due diligence. But because on the facts of this case the prosecution’s lack of diligence was harmless, I concur in the judgment.