Can a change of mind occur during the penalty phase of a murder trial?

In People v. Bolter, supra, 227 Cal.App.3d at pages 659-662, 278 Cal.Rptr. 123, a case involving a bifurcated murder trial, the jury returned a verdict of guilty and proceeded to hear evidence during the penalty phase of trial. A juror then indicated that she was inclined to change her mind about the guilty verdict. (Id. at p. 659, 278 Cal.Rptr. 123.) The court in Bolter concluded that the verdict of guilty was complete, and the trial court did not err in failing to investigate the juror's change of mind because it lacked jurisdiction to reconvene jury deliberations on guilt. (Id. at p. 660, 278 Cal.Rptr. 123.) The Bolter court reasoned that the trial court had lost the ability to shield the jurors from improper influences when they were exposed to new evidence pertinent to guilt during the penalty phase, and thus the presentation of this evidence " 'had the same effect as a discharge [.]' " (Id. at p. 661, 278 Cal.Rptr. 123, emphasis omitted, quoting People v. Bonillas, supra, 48 Cal.3d at p. 774, 257 Cal.Rptr. 895, 771 P.2d 844.)