OPINION OF THE COURT BY
HAYASHI, J.This is an appeal by the State of Hawaii from a judgment of acquittal granted by Judge Huddy under Hawaii Revised Statutes *71(HRS) § 704-408. Appellant claims, and we agree, that there was sufficient evidence presented so as to require the judge to present the issue of sanity to the jury.1 We also decide that a defense of multiple personality syndrome (MPS) does not per se require a finding of acquittal.
Defendant was indicted on November 20,1979, on three counts of sodomy in the first degree (HRS § 707-733(l)(a)(i)) and one count of rape in the first degree (HRS § 707-730(l)(a)(i)). His victims were all young girls, whom he would lure into secluded areas. He filed a notice of intention to rely on the defense of mental disease, disorder or defect under HRS § 704-404(1) on March 12, 1980. Defendant had previously been examined by Vadim P. Kondratief, M.D. in California, who referred defendant to Bernauer W. Newton, Ph.D., also in California, both of whom testified for the defense.
On March 17, 1980, the court pursuant to HRS § 704-404(2), ordered further mental examination of the defendant to be performed by three court appointed psychiatrists: Drs. Creighton U. Mattoon, Emily Khaw and Gene Altman.
On October 16, 1980, the defendant filed a motion for judgment of acquittal. Hearings on that motion and a motion for closure of the hearings were held intermittently beginning December 1, 1980. On December 2, the court consolidated the hearing on the motion for acquittal with a motion for determination of fitness to proceed.
On January 9, 1981, the judge found defendant unable to assist iñ his defense, and pursuant to HRS § 704-406 suspended the proceedings, deferring the matter of acquittal.
For the next year and a half, State psychiatrist Dr. Morgan treated defendant at Hawaii State Hospital in Kaneohe, and on June 25, 1982, the defendant was brought back into court. The defendant was presented as fit to proceed, so the court renewed hearings on the motion for the judgment of acquittal. On August 27, 1982, the judge granted the motion, and this appeal followed.
*72I.
In every criminal case there exists a presumption that a defendant is sane. This presumption can be overcome by evidence to the contrary, and then the State has the burden of proving a defendant’s sanity beyond a reasonable doubt. State v. Valentine, 1 Haw. App. 1, 612 P.2d 117 (1980).
The defendant in the case at hand introduced testimony from five psychiatrists to rebut the presumption of sanity. There was no contention that this was not sufficient to rebut the presumption. Accordingly, the burden of proof shifted to the State to prove, beyond a reasonable doubt, that appellant was sane at the time of the offenses.
The testimony introduced by the defense addressed the fact that under HRS § 704-408, a defendant will be relieved of criminal responsibility if at the time of the alleged conduct the defendant suffered from a mental disease, disorder, or defect which substantially impaired his capacity to appreciate the wrongfulness of his conduct or to conform his conduct to the requirements of the law. In support of his motion for acquittal, the defendant raised the defense that at the time of the offense he was suffering from multiple personality syndrome, which should exclude his responsibility for his actions.
Multiple personality syndrome (MPS) is a disorder where there are within one individual, two or more distinct personalities, each of which is dominant at a particular time. Each individual personality is complex and integrated with its own behavior pattern and the personality that is dominant at any particular time determines the individual’s behavior. Often there is amnesia on the part of one personality for the existence of the other.2
The defense of MPS was raised in connection with HRS § 704-408 because one personality often cannot control the actions of another personality. This disorder is extremely rare, and has recently come to the attention of several courts. The trend in these courts is toward examining the sanity of each personality presented *73in an individual, or at least the personality which allegedly committed the offense.
The law adjudges criminal liability of the person according to the person’s state of mind at the time of the act; we will not begin to parcel criminal accountability out among the various inhabitants of the mind.
Kirkland v. State, 166 Ga. App. 478, 304 S.E.2d 561, 564 (1983). Recent cases dealing with the multiple personality defense have held that it is immaterial whether the defendant was in one state of consciousness or another, so long as in the personality then controlling the behavior, the defendant was conscious and his or her actions were a product of his or her own volition. State v. Darnall, 47 Or. App. 161, 614 P.2d 120 (1980); State v. Grimsley, 3 Ohio App. 3d 265, 444 N.E.2d 1071 (1982); and Kirkland, supra.
The cases dealing with MPS can be examined in a similar fashion as other defenses of insanity. If a lunatic has lucid intervals of understanding he shall answer for what he does in those intervals as if he had no deficiency. The law governs criminal accountability where at the time of the wrongful act the person had the mental capacity to distinguish between right and wrong or to conform his conduct to the requirements of the law. Since each personality may or may not be criminally responsible for its acts, each one must be examined under the American Law Institute (ALI)-Model Penal Code (MPC) competency test. See State v. Nuetzel, 61 Haw. 531, 606 P.2d 920 (1980); and Kirkland, supra.
II.
Before we examine the testimony relating to the competency of the alleged personalities of the defendant elicited from the psychiatrists, we must address defendant’s claim that the court erred in not striking the testimony of one of the psychiatrists, Dr. Khaw.
Generally, in determining whether the conclusions or opinions of an expert witness are admissible, the court must exercise a large measure of discretion with which an appellate court is reluctant to interfere unless that discretion has been manifestly abused to the prejudice of the complaining party. State v. Torres, 60 Haw. 271, 589 P.2d 83 (1978); 31 Am. Jur. 2d Expert and Opinion Evidence § 3. *74The determination of qualification is in the first instance for the court, and is discretionary. But qualifications also go to weight, and Hawaii Rules of Evidence (HRE) Rule 702.1, expressly provides for cross-examination on this subject. See, State v. Okura, 56 Haw. 455, 541 P.2d 9 (1975).
The standard of review therefore, is whether the court abused its discretion in failing to strike the testimony. Defendant argues, and we agree, that the qualifications and methodology of the doctor had been seriously called into question, and we also agree that the trial court gave little, if any weight to Dr. Khaw’s testimony.
Court: I’ll find her qualified as a psychiatrist, and in that capacity, with expertise to render diagnosis and treatment of people who may or may not be affected with a mendal [sic] disorder, which includes multiple personality. But it’s always for the trier of fact to weigh and evaluate the opinion of any expert, and the trier of fact may accept or reject it. So the question is again to the weight and effect for trier of fact to give to the testimony.
Tr. 1/6/81 at 49. But we disagree with defendant’s contention that:
[h]ad Defendant’s motion (to strike Dr. Khaw’s testimony) been granted, the court below would have been entirely without any evidence or inferences required to be drawn therefrom pursuant to State v. Freitas, supra, and State v. Summers, supra, other than the exensive [sic] evidence of insanity and lack of penal responsibility adduced by Defendant. On that state of the record, the judgment of acquittal below would have been compelled.
Defendant’s Answering Brief at 30. Defendant has failed to show a clear abuse of discretion or any resulting prejudice from the introduction of the testimony, because as will be noted below, the question of acquittal was one for the jury or trier of fact, who could have given Dr. Khaw’s testimony the weight it deserved. There was also other evidence elicited from the other psychiatrists which could support an inference that defendant was sane.
III.
An examination of the testimony of the psychiatrists reveals that few of the experts agreed as to any of their opinions.
Dr. Kondratief, the first to examine the defendant, had not *75treated nor diagnosed anyone who had MPS, and had only seen two or three cases of MPS. Before he referred the defendant to Dr. Newton, he had formed a diagnosis that the defendant was suffering from fugue, temporary amnesia or MPS. After discussing the matter with Dr. Newton, he formed a final diagnosis of MPS. His opinion was that defendant as a whole lacked substantial capacity to appreciate the wrongfulness of his conduct and also lacked substantial capacity to control his conduct to the requirements of the law. He testified that personality A had no control or knowledge of personality B. He also testified that B was not capable of understanding the proceedings against him, but never expressed his opinions as to whether A or B could control their actions or appreciate the wrongfulness of their conduct as separate personalities.
Dr. Newton treated the defendant through hypnosis, and prepared tapes of his sessions which allegedly showed defendant’s several personalities. He had diagnosed seventeen cases of MPS and had treated eleven patients for MPS, and stated that the defendant as a whole was capable of appreciating the wrongfulness of his1 conduct, but was not capable of conforming his conduct to the requirements of the law. He stated that personality A understood the charges against him and could conform his behavior to the requirements of the law. He testified that defendant was in the B state when he committed the acts, and that B could appreciate the wrongfulness of his acts but could not conform his behavior to the requirements of the law.
Dr. Altman, one of the court appointed psychiatrists, had never treated or diagnosed any cases of MPS. After viewing a summary tape prepared by Dr. Newton, and discussing the case with Dr. Newton, he came to his diagnosis that defendant suffered from MPS. He stated that personality B had committed the offenses, that B knew that what he was doing was wrong, and that B had some degree of volitional control over his actions.
Dr. Khaw, another court appointed psychiatrist, had never treated nor diagnosed nor even seen a case of MPS. After viewing the summary tape prepared by Dr. Newton, she still claimed to never have seen a case of MPS. Her diagnosis was that defendant’s mental condition was sexual perversion, pedophilia. She stated that defendant knew what was wrong and could conform his behavior *76to the requirements of the law, although it was difficult for him to do so.
Dr. Mattoon, the last of the court appointed psychiatrists, testified that he had never diagnosed, treated, nor seen anyone with MPS. He diagnosed defendant as having MPS after talking with Dr. Newton for four hours in the court halls before testifying. He stated that both A and B could understand that the acts were wrong, but that it did not matter to B. He testified that A could control himself to the requirements of the law, as could B, and that it was B who performed the acts.
Finally Dr. Morgan, who had treated six cases of MPS, stated that he wasn’t sure that the defendant had MPS until after he began treating him. (Dr. Morgan had testified earlier that defendant had MPS, but after treating the defendant he testified that during his earlier testimony he actually was unsure of whether defendant had MPS.) After treating him for approximately six hundred hours, Dr. Morgan came to the conclusion that defendant had in fact three personalities: personality A, named Pod, was defendant’s normal waking state; personality B, named David, emerged at age sixteen and was the mediating personality between Rod and the final personality; the last personality’s name was Lucifer, who emerged at age three, and who had taken over at the times of the offenses. Dr. Morgan testified that the defendant as a whole lacked the capacity to appreciate the wrongfulness of his conduct and to conform his behavior to the requirements of the law. He testified that A and B knew that the acts were wrong but that C did not care whether they were right or wrong and that A and B had the capacity to conform their conduct to the requirements of the law but C did not care about his conduct or the consequences.
A summary of the testimony of all the psychiatrists reveals that: defendant had anywhere from one to three personalities; A could appreciate the wrongfulness of his acts and conform his behavior to the requirement of the law, but could not control B; B could understand the wrongfulness of his conduct but could or could not (depending on whose testimony was more persuasive) control his behavior to the requirements of the law; and C did not care whether what he did was right or wrong or about the consequences of his conduct. Dr. Khaw, theorizing there was one personality, *77testified A committed the acts; four doctors theorizing there were two personalities, testified B committed the acts; and Dr. Morgan testified that C executed the crimes.
IV.
In light of the above testimony, we find merit to the appellant’s claim that the judge erred in granting the acquittal without giving the matter to the jury. The standard of review on appeal is that it is a jury question unless a reasonably minded jury viewing the facts and inferences in a light most favorable to the prosecution would necessarily possess a reasonable doubt as to defendant’s sanity. State v. Nuetzel, 61 Haw. 531, 606 P.2d 920 (1980). State v. Freitas, 62 Haw. 17, 608 P.2d 408 (1980), held that where the evidence is such that a jury might fairly have or not have a reasonable doubt as to defendant’s sanity, the issue becomes a question of fact for the jury, and a motion for judgment of acquittal will be denied. The testimony in this matter is disjointed and:
[w]hat psychiatrists may consider a mental disease or defect for medical purposes where clinical treatment is the main concern may not be the same as mental disease or defect for the jury’s purpose where an accused’s criminal responsibility is at issue.
State v. Nuetzel, 61 Haw. at 543, 606 P.2d at 928. The expert may testify as to mental states, but they are not competent to render an opinion as to the impact of the mental state on legal accountability. This is a question for the jury where, as here, there are divers opinions as to which personality performed the acts and whether that personality was sane or not.
The purpose of expert testimony is to assist the trier of fact on matters not of common knowledge, where the witnesses have knowledge, training and experience enabling them to form a better opinion on a given state of facts than that formed by those not so well equipped. 31 Am. Jur. 2d Expert Opinion and Testimony § 16. The jury is entitled to know the facts on which an expert bases his opinion in order to make its own assessment of the expert’s opinion and the reliability of the diagnostic and analytical process employed. State v. Summers, 62 Haw. 325, 614 P.2d 925 (1980).
It is well settled that we are not bound by expert testimony as to the sanity or mental state of an accused, even where it is undis*78puted, but the fact finder may reject it out of hand.
Kirkland, supra, at 565; see also, Bachran v. Morishige, 52 Haw. 61, 469 P.2d 808 (1970). Since the jury may reject an expert’s testimony, it would appear axiomatic that they could reject part of the testimony of an expert. Thus they could accept one psychiatrist’s testimony as to whether a defendant could appreciate the wrongfulness of his actions, and accept another psychiatrist’s testimony regarding the capability of the defendant to conform his conduct to the requirements of the law. They could therefore arrive at a conclusion conjectured by no one expert alone.
V.
It also appears in this case, that the trial judge improperly weighed the testimony of the doctors, and acted as a trier of fact rather than a judge on the motion for acquittal.
The Court: The only question that the Court had in that regard was Dr. Khaw’s testimony. But in review of her testimony, giving full weight and effect to her testimony, the Court placed some emphasis on her testimony to the effect that she believed that it was very, very hard for the defendant to control his conduct or to conform his conduct to the requirements of law. She used phrases such as “very, very hard.” “I think he can.” “Difficult.” And, when the Court weighs that testimony along with the testimony of Dr. Newton and the other doctors who have testified, the Court has reached the conclusion that necessarily a judgment of acquittal is required in this case.
Tr. 8/27/82 at 60-61.
The Court: The impact, the effect of the weight of the testimony is for the trier of facts.
The Court: I can weigh it.
Tr. 12/16/80 at 54. The weighing of testimony is reserved for the jury or trier of fact unless no reasonable juror could disagree as to an outcome. State v. Summers, supra. The sanity issue before this court and the role of the jury was discussed in Nuetzel.
The jury, as the trier of facts, remains the sole sentinel in the protection of both the rights of the accused and the welfare of society, enabled finally to consider all relevant facts pertaining *79to the defendant’s state of mind at the time the act was committed, and being thereby better qualified to render its ultimate moral judgment under the law.
State v. Nuetzel, 61 Haw. at 543, 606 P.2d at 928. The judge acted improperly in granting the motion for acquittal in this case.
We hold therefore, that the question of defendant’s sanity at the time of the offense and the corresponding question of which personality was present at the time of the offense were questions properly for the jury or the trier of fact.
VI.
While defense counsel at oral argument conceded that this court probably had jurisdiction under HRS § 641-13(2) to hear this case because no jury had been impanelled, we feel it necessary to discuss the issue of double jeopardy.
Under HRS § 641-13(2), an appeal may be taken by and on behalf of the State “from an order or judgment, sustaining a special plea in bar, or dismissing a criminal case where the defendant has not been put in jeopardy.” Double jeopardy does not attach unless there is a risk of a determination of guilt. Serfass v. United States, 420 U.S. 377, 95 S. Ct. 1055, 43 L. Ed. 2d 265 (1974). In State v. Hagerud, 174 Mont. 361, 570 P.2d 1131 (1977), defendant was acquitted by reason of mental defect excluding responsibility in a pretrial evidentiary hearing to determine whether defendant at the time of the offense.charged was so clearly unable to appreciate the criminality of his conduct or conform his conduct to the requirements of the law that trial would be useless. On appeal, the court held that the defendant was never once put in jeopardy as he was never subjected to the possibility of conviction of the crime charged and, thus, to permit the State to obtain review of the district court’s decision acquitting defendant did not put defendant in double jeopardy in violation of his constitutional rights.
Hawaii case law has recognized two inquiries which must be made to determine whether double jeopardy has attached. The first is to determine when jeopardy attaches, and the second is to determine if, on the facts of the case, a retrial is barred by the double jeopardy clause. State v. Miyazaki, 64 Haw. 611, 645 P.2d 1340 (1982). Here no jeopardy attached. This was a pretrial motion *80to determine whether defendant at the time of the offense charged was unable to appreciate the wrongfulness of his conduct or to control his conduct to the requirements of the law. There was no possibility of a conviction, and thus a trial is not barred by the double jeopardy clause of the Fifth Amendment.
Arthur E. Ross (Ernest J. Freitas, Jr. on the reply brief), Deputy Prosecuting Attorneys, for plaintiff-appellant. John S. Edmunds (RonaldJ. Verga, with him on the brief; John S. Edmunds, A Law Corporation, of counsel) for defendant-appellee.Accordingly, the decision of the lower court is vacated and the case remanded for further proceedings consistent with this opinion.
HRS § 704-408 was amended by the legislature in 1980 to require the court to submit the issue of criminal responsibility to the jury or trier of fact at the trial of the charges against the defendant. The amendment does not apply to this case, however, since it does not apply to any crime which occurred prior to June 7, 1980.
French and Shechmeister, The Multiple Personality Syndrome and Criminal Defense, 11 Am. Acad. Psych. & L. Bull. 1 at 17-25 (1983).
HRS § 704-404(1) reads:
Whenever the defendant has filed a notice of intention to rely on the defense of physical or mental disease, disorder, or defect excluding responsibility, or there is reason to doubt his fitness to proceed, or reason to believe that the physical or mental disease, disorder, or defect of the defendant will or has become an issue in the case, the court may immediately suspend all further proceedings in the prosecution. If a trial jury has- been empanelled, it shall be discharged or retained at the discretion of the court. The dismissal of the trial jury shall not be a bar to further prosecution.