As this California court explained, " 'In Faretta v. California (1975) 422 U.S. the United States Supreme Court held that a defendant in a state criminal prosecution has a constitutional right under the Sixth and Fourteenth Amendments to waive counsel and represent himself. Once defendant asserts this right, the court must determine whether he has the mental capacity to make a voluntary and intelligent waiver of the right to counsel." ( People v. Robinson (1997) 56 Cal. App. 4th 363, 371 [65 Cal. Rptr. 2d 406], quoting People v. Nauton (1994) 29 Cal. App. 4th 976, 979 [34 Cal. Rptr. 2d 861], italics added). However, "when a defendant has elected to proceed to trial represented by counsel and the trial has commenced, it is thereafter within the sound discretion of the trial court to determine whether such a defendant may dismiss counsel and proceed pro se." (People v. Windham, supra, 19 Cal. 3d at p. 124).