Does the Attorney General have any authority to prevent a defendant from changing his theory in the middle of trial?

The undercurrent in the Attorney General's brief is the notion that defendant should not be allowed to change his theory in the middle of trial, despite the change in the state of the evidence. But that is not the law, and the Attorney General presents no authority to that effect. "'Jury instructions must be responsive to the issues. The issues in a criminal case are determined by the evidence.'" (People v. Jeter (1964) 60 Cal.2d 671, 674.) Defendant "is entitled to have the jury instructed on the law applicable to the evidence he presents. Doubts as to the sufficiency of the evidence to warrant instructions should be resolved in [his] favor." (People v. Wilson (1967) 66 Cal.2d 749, 763.)