What is the burden of proving undue delay in filing a charge?

" 'A defendant seeking relief for undue delay in filing charges must first demonstrate resulting prejudice, such as by showing the loss of a material witness or other missing evidence, or fading memory caused by the lapse of time. [Citation.] Prejudice to a defendant from precharging delay is not presumed. [Citations.] . . . [I]f the defendant fails to meet his or her burden of showing prejudice, there is no need to determine whether the delay was justified. [Citations.]' [Citation.]" (People v. Jones, supra, 57 Cal.4th at p. 921, italics added.)