Is it improper for a prosecutor to comment upon a defendant's failure to introduce material evidence or call logical witnesses?

380 U.S. 609, 615 [14 L.Ed.2d 106, 110].) On the other hand, it is not improper for a prosecutor to "comment upon a defendant's failure 'to introduce material evidence or to call logical witnesses.' " (People v. Wash (1993) 6 Cal.4th 215, 263.) A prosecutor commits misconduct, however, "when he purports to tell the jury why a defense witness did not testify or what the testimony of that witness would have been." (People v. Gaines (1997) 54 Cal.App.4th 821, 822.)