Concurring and Dissenting.—I concur in the judgment as to guilt and death eligibility. Although I believe that one of the multiple-murder special-circumstance findings must be vacated, I have found no error warranting reversal on either of those two issues.
I dissent, however, as to penalty. As I shall explain, the trial court erred prejudicially by ruling as it did on defendant’s motion for a hearing on mental competence.
Penal Code section 1367 declares that “A person cannot be tried or adjudged to punishment while such person is mentally incompetent.” The due process clauses of the Fifth and Fourteenth Amendments to the United States Constitution entitle a defendant to a hearing on the question of *1156competence as a matter of right if he comes forward with substantial evidence of incompetence. (People v. Stankewitz (1982) 32 Cal. 3d 80, 92 [184 Cal.Rptr. 611, 648 P.2d 578, 23 A.L.R.4th 476]; People v. Pennington (1967) 66 Cal.2d 508, 518 [58 Cal.Rptr. 374, 426 P.2d 942].) So too do the due process clauses of article I, sections 7 and 15, of the California Constitution. The denial of a hearing when the foregoing condition is met is violative of due process and prejudicial per se. This is true under the federal charter. (People v. Stankewitz, supra, 32 Cal.3d at p. 94; People v. Pennington, supra, 66 Cal.2d at p. 521.) It is also true under the state charter. Beyond question, the due ¡process clauses of the federal and state Constitutions each entitle a defendant to an opportunity to come forward with evidence of incompetence. The denial of such an opportunity is itself violative of each of the constitutional guaranties and prejudicial per se: the defect renders the procedure fundamentally unfair and its result substantially unreliable.
Immediately before sentencing, defendant moved through counsel for a hearing on mental competence and requested permission to call Dr. Gloria Keyes, a psychiatrist, in order to present evidence of incompetence. The trial court perfunctorily denied the motion and summarily refused the request.
By acting as it did, the trial court committed prejudicial error. It plainly denied defendant an opportunity to come forward with evidence of incompetence—evidence he was “ready, willing, and able” to present through the testimony of Dr. Keyes.
The majority find no error. Their reasoning, however, does not support their conclusion.
It may well be that a court may deny a motion for a hearing on mental competence because of an inadequate offer of proof. The court here could not have properly denied defendant’s motion on that basis. It did not request or allow any offer of proof. Be that as it may, it simply did not deny the motion for that reason. It made plain that it would consider no evidence of incompetence to be substantial, no matter what such evidence might establish: “I have not the slightest doubt of this defendant’s sanity or competency to assist with the defense.” Having reviewed the record, I am inclined to agree with the court’s implicit finding that defendant was often unwilling to cooperate with counsel. But the issue that was crucial—and crucially distinct—was whether defendant was able to do otherwise.
Further, it may well be that after it has conducted a hearing on mental competence, a court may deny a motion for a subsequent hearing unless it is presented with a change of circumstances or new evidence. The court here *1157could not have properly denied defendant’s motion under this principle. Counsel clearly showed a change in circumstances. Since defendant had been found competent prior to trial, almost 18 months had passed and the verdicts and findings determining guilt and penalty had been returned. More clearly still, counsel offered new evidence. Dr. Keyes was a new witness; she had formed a new opinion; and her opinion rested on a new basis.
To be sure, the trial court’s erroneous denial of an opportunity for defendant to come forward with evidence of mental incompetence is understandable. Evidently, defendant’s refractory behavior tried the patience of practically everyone below. Although understandable, the court’s denial was nonetheless erroneous—and prejudicial per se.
Accordingly, I would vacate the judgment as to penalty and remand the cause to the trial court with directions to give defendant the opportunity to raise and litigate the issue of mental competence, and thereafter to impose the appropriate sentence.
Appellant’s petition for a rehearing was denied September 19, 1991. Mosk, J. was of the opinion that the petition should be granted.