Can a trial judge reasonably find that a minor made a knowing and voluntary waiver of his Miranda rights?

[104 Cal.App.3d 621] The record of the entire conversation between the minor and the officers, which lasted approximately 30 minutes, does not "reflect(s) an atmosphere free of intimidation and coercion." On the contrary, this record convinces me that the minor's confession was obtained by "intimidation and coercion." I can see no basis for a holding that the trial judge could reasonably find that the minor made a knowing and voluntary waiver of his Miranda rights. In People v. Jimenez (1978) 21 Cal.3d 595, 147 Cal.Rptr. 172, 580 P.2d 672, the high court established the burden-of-proof rule that when a defendant raises the issue that his confession was involuntary, the burden is upon the prosecution to prove beyond a reasonable doubt that the confession was voluntary as a preliminary fact to the admissibility of the confession.