OPINION
STOWERS, Justice.The State of New Mexico petitioned this Court on a writ of certiorari to review the judgment of the Court of Appeals in State v. Chapman, Ct.App. No. 7299 (Filed November 23, 1983). The jury found the respondent competent to stand trial and the Court of Appeals reversed. The Court of Appeals determined that the State’s evidence failed to establish that the respondent could rationally consult with his attorney with a reasonable degree of understanding or rationally perceive and comprehend the events in question.
The issue we decide on certiorari is whether the Court of Appeals substituted its judgment of the facts for that of the jury by finding that the facts did not support the jury’s determination that the respondent could assist his attorney. We hold that the Court of Appeals improperly substituted its judgment for that of the jury, and therefore’ reverse.
The respondent was charged with the murder of his parents. In two prior proceedings, the respondent was adjudged mentally incompetent to stand trial. In late 1982, the State again moved to reevaluate the respondent’s competency. After a jury trial on April 21, 1983, during which both sides presented expert testimony, the jury found the respondent competent to stand trial.
Due to the prior adjudication of incompetency, the burden was on the State to go forward with the evidence and to overcome a presumption of incompetency by a preponderance of the evidence. State v. Santillanes, 91 N.M. 721, 580 P.2d 489 (Ct.App.1978). The State contends that it met the burden of proving the respondent’s competency. The State further argues that the reversal of the jury decision was the result of the Court of Appeals’ reweighing the evidence. The competency of an accused must be proven by a preponderance of the evidence rather than beyond a reasonable doubt, and substantial evidence must be presented to support such a determination. See State v. Santillanes. Substantial evidence consists of such relevant evidence which is acceptable to a reasonable mind. State v. Armstrong, 82 N.M. 358, 482 P.2d 61 (1971).
In the present case, the jury was given a modified version of NMSA 1978, UJI Crim. 41.01 (Repl.Pamp.1982). UJI Crim. 41.01'has subsequently been revised and its present form is found at NMSA 1978, UJI Crim. 41.03 (Cum.Supp.1984). In this case, the jury was instructed as follows:
Evidence has been presented concerning the defendant’s competency to stand trial. The State has the burden of proving by the greater weight of the evidence that the defendant is mentally competent to be tried.
A person is competent to stand trial if he:
1. Understands the nature and gravity of the proceedings against him;
2. understands he is being tried on a serious charge; and
3. is capable of assisting in his own defense.
As to this issue only, your verdict need not be unanimous. When, as many as ten of you have agreed as to whether the defendant is competent to stand trial, your foreman must sign the proper form. [Instruction No. 2]
The State contends that the Court of Appeals improperly reweighed the evidence presented to the jury and then decided that there was insufficient evidence to show that the respondent met the third element required by former UJI Crim. 41.01. We agree. While conflicting expert testimony was presented at trial, the jury, as the fact finder, was not bound by, nor required to accept, the opinions of any of these experts. State v. Victorian, 84 N.M. 491, 505 P.2d 436 (1973). See also NMSA 1978, UJI Crim. 40.50 (Repl.Pamp.1982).
The record indicates that the State’s expert witness, Dr. Egelman, testified that the respondent had a good recollection of the events surrounding the killing and the killing itself. Dr. Egelman stated that the reason the respondent gave for killing his parents was a delusion. Furthermore, Dr. Egelman acknowledged that the respondent suffered from a mental illness. However, Dr. Egelman also testified that this illness did not mean that the respondent was not competent to stand trial because he could aid his attorney and was aware of the charges pending against him. On cross-examination, Dr. Egelman maintained that the respondent’s illness affected his reason for acting where his family was concerned, but not his ability to assist his lawyer. A defense expert testified that the respondent understood the charges and was aware of the roles of individuals in court proceedings; however, the respondent was unable to properly consult with and assist counsel. The conflicting expert testimony presented in this case does not change the right of the jury to accept or disregard such testimony. The jury was not required to accept the opinion of any of these experts. See State v. Victorian.
In concluding that the delusions suffered by the respondent rendered him unable to assist his attorney in formulating a rational defense, the Court of Appeals impermissibly substituted its own judgment for that of the jury. In State v. Lopez, 91 N.M. 779, 780, 581 P.2d 872, 873 (1978), this Court stated:
In reviewing the present case the appellate court should only examine the evidence to determine whether the trial court abused its discretion. The reviewing court cannot substitute its judgment for that of the trial court (citations omitted).
Similarly, the appellate court may not substitute its judgment for that of the jury. State v. Martinez, 95 N.M. 795, 626 P.2d 1292 (Ct.App.1979); State v. Elam, 86 N.M. 595, 526 P.2d 189 (Ct.App.), cert. denied, 86 N.M. 593, 526 P.2d 187 (1974). In the present case, the Court of Appeals erred in substituting its judgment of the facts for that of the jury by finding that the facts of this case did not support the jury’s determination that the respondent could assist his attorney. Moreover, the verdict of the jury is supported by substantial evidence.
The Court of Appeals is reversed. The jury’s determination that this respondent is competent to stand trial is hereby affirmed.
IT IS SO ORDERED.
FEDERICI, C.J., SOSA, Senior Justice and RIORDAN, J., concur. WALTERS, J., dissents.