What is the burden of proving a defendant's waiver of the Miranda rights?

In the Miranda arena, " '[t]he prosecution bears the burden of demonstrating the validity of the defendant's waiver by a preponderance of the evidence.' [Citations.] In addition, '[a]lthough there is a threshold presumption against finding a waiver of Miranda rights [citation], ultimately the question becomes whether the Miranda waiver was [voluntary,] knowing [,] and intelligent under the totality of the circumstances surrounding the interrogation.' [Citation.] On appeal, we conduct an independent review of the trial court's legal determination and rely upon the trial court's findings on disputed facts if supported by substantial evidence." (People v. Williams, supra, 49 Cal.4th at p. 425.)

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