A witness who was deported to Mexico prior to trial was not “unavailable” in the constitutional sense because the prosecution’s efforts to make the witness available for trial did not constitute due diligence under the law. Appellant was charged with attempted murder and other offenses in connection with a shooting. The victim, Barrera, testified against appellant at the preliminary hearing while he was in county jail on an immigration hold. Following the hearing, he was deported to Mexico and the defense was not informed until the first day of trial. The prosecution investigator, knowing that the deportation was in process, did not obtain specific information about how to contact Barrera and informal negotiations with ICE to keep him beyond the preliminary hearing failed. Over defense objection, the trial court admitted Barrera’s preliminary hearing testimony at trial, which was the only direct evidence of guilt, and appellant was convicted. The Court of Appeal agreed with appellant that the prosecution failed to use due diligence in attempting to secure Barrera’s attendance at trial. The prosecution’s duty includes the use of reasonable means to prevent a witness from becoming absent as well as using due diligence to find a witness who has gone missing. Knowing that Barrera was going to be deported, there were steps the prosecution could have taken to protect the defendant’s right of confrontation such as videotaping the preliminary hearing so that the jury could see and hear the testimony, seeking Barrera’s detention as a material witness under Penal Code section 1332, seeking delay of his deportation under federal regulations, or applying for a writ of habeas corpus ad testificandum in federal court. Here, there was no record documenting precisely what efforts the prosecution undertook to secure Barrera’s attendance at trial. The Sixth Amendment demands a more particularized showing of due diligence for the prosecution to meet its burden of proof to establish unavailability.