What is the scope of our review of a constitutional claim of illegal obtaining?

" 'The scope of our review of constitutional claims of this nature is [likewise] well established. We must accept the trial court's resolution of disputed facts and inferences, and its evaluations of credibility, if they are substantially supported. [Citations.] However, we must independently determine from the undisputed facts, and those properly found by the trial court, whether the challenged statement was illegally obtained. [Citation.]' "⁷ (People v. Johnson (1993) 6 Cal.4th 1, 25.)