What is the burden of proving that a delay in bringing a criminal charge of sexual assault caused actual prejudice?

"The defendant has a heavy burden to prove that a preindictment delay caused actual prejudice: the proof must be definite and not speculative, and the defendant must demonstrate how the loss of a witness and/or evidence is prejudicial to his case." Moran, 759 F.2d at 782 (citations omitted). Our cases reflect this heavy burden, as we frequently find actual prejudice lacking. See, e.g., Wallace, 848 F.2d at 1470; United States v. Valentine, 783 F.2d 1413, 1416-17 (9th Cir.1986). Here, we find the showing of prejudice to be slim.