What is the burden of presenting proof of actual prejudice when a defendant cannot locate a witness?

The burden of presenting proof of actual prejudice is on the defendant. Carruth, 699 F.2d at 1019. To establish actual prejudice due to the inability to locate a witness sufficient to warrant dismissal of an indictment, a defendant must not only establish his inability to locate the witness, but also must demonstrate that the loss of this witness and his or her expected testimony has prejudiced him. United States v. Mays, 549 F.2d 670, 677 (9th Cir.1977). Such proof must be definite and not speculative. Carruth, 699 F.2d at 1019. This means that the defendant must actually show that the loss of the witness has impaired his ability to defend himself meaningfully. Cederquist, 641 F.2d at 1351.