The primary issue in this case is concerned with the nature of the evidence a defendant in a criminal proceeding must present in order to require the issue of mental illness or deficiency to be decided by *961the jury. A second issue which we will resolve is, assuming that some such evidence is produced, can the State of Wyoming then rely upon the presumption of sanity in order to avoid a judgment of acquittal? In this case the district court refused to submit the issue of mental illness or deficiency to the jury. We find that the defendant did introduce sufficient evidence to require the submission of that issue to the jury, and we will reverse the defendant’s conviction of the crime of involuntary manslaughter and remand the case to the district court for a new trial. In so doing we will hold that when the defendant produces evidence of mental illness or deficiency the presumption of sanity cannot be relied upon by the State of Wyoming, but there must be present affirmative evidence tending to establish beyond a reasonable doubt that the defendant was mentally responsible at the time of the crime.
On July 6, 1977, Thelma Kind’s four-month-old son drowned in the bathtub at her apartment in Buffalo, Wyoming. The undisputed evidence is that she left the baby in the bathtub, with the drain stopped and the water running, while she went to attend to some laundry which she was doing. Evidence of Thelma Kind’s statements to others discloses that she reported she was absent from the bathroom for only a short time. An investigative officer testified that he performed an experiment on the bathtub, and that when running the water at the rate Thelma Kind showed him she had it running when the baby drowned it took 22 minutes, 43½ seconds for the tub to fill to the overflow. Thelma Kind summoned help for her infant son, but the baby was dead at the hospital, all attempts at resuscitation having proved unsuccessful.
The Information filed by the county attorney charged Mrs. Kind with both voluntary and involuntary manslaughter in violation of § 6-58, W.S.1957 (now § 6-4-107, W.S.1977). The Information was amended prior to trial to delete an allegation that the homicide was committed involuntarily in the commission of an unlawful act. After receiving the State’s evidence, the trial court eliminated the State’s theory of voluntary manslaughter upon a sudden heat of passion, and the case was submitted on the theory of involuntary manslaughter by culpable neglect or criminal carelessness on Thelma Kind’s part. The jury found Thelma Kind guilty of involuntary manslaughter.
Appropriate instructions were requested by Thelma Kind for the submission to the jury of the issue of mental illness or deficiency. While it is noted that these instructions are not in the form suggested by § 4.101, Wyoming Pattern Jury Instructions, Criminal, no issue is raised that the instructions were not in proper form. Thelma Kind also requested a form of verdict for the purpose of submitting to the jury the question of mental illness or deficiency. These requests were refused by the district judge, who commented:
“ * * * I might say for the record just so it doesn’t look like at the present stage that I’m just arbitrarily off the top of my head refusing these instructions, have the record show that counsel and the Court had a rather extended discussion as to whether or not the defense had established the question of mental deficiency so as to raise it as an issue, and we attempted to work out something whereby it could be brought out if certain portions of the Wyoming State Hospital report dated October 12, 1977, were admitted by stipulation, and we couldn’t work out that stipulation, and therefore, the Court has considered that there was not sufficient evidence to raise the presumption of mental deficiency to an extent that the defendant, at the time of the alleged criminal conduct, as a. result of mental illness or deficiency, lacked substantial capacity to appreciate the wrongfulness of her conduct or to conform her conduct to the requirements of law. * * *”
The evidence upon which Thelma Kind premises her appeal from the trial court’s ruling may be summarized briefly. Exhibit A was a psychological evaluation of Thelma Kind which was accomplished within a *962month of her son’s death. The primary diagnosis was inadequate personality with a secondary diagnosis of anti-social personality. She was found to be possessed of below average intelligence, and only did well when presented with concrete thought problems. Exhibit B was a summary of an evaluation at the Wyoming State Hospital which was accomplished in 1972 and 1973. The final diagnosis there was borderline mental retardation, psychosocial (environmental) deprivation, and schizophrenia, paranoid type. This exhibit included a report of Thelma Kind’s accounts of auditory hallucinations involving a dead brother, a similar visual hallucination, hearing voices in which her name is mentioned, and feelings of being followed. Exhibit C contained information relative to Thelma Kind’s commitment to the Wyoming State Children’s Home which included a report from a psychological clinic which diagnosed her as an inadequate personality. An expert witness who had done the psychological examination which was marked as Exhibit A testified about this diagnosis, and its manifestations in Thelma Kind’s instance.
In presenting her appeal, Thelma Kind states the issues as follows:
“I. Whether the trial judge was required by § 7-ll-305(a) to submit to the jury a verdict by which it could find the defendant not guilty by reason of mental illness or deficiency excluding responsibility.
“II. Whether if this court adheres to the ‘some evidence’ test concerning quantum of evidence necessary to raise the issue of mental illness or deficiency, this burden was clearly met by the defendant.
“HI. Whether the court below in determining if the question of sanity should be submitted to the jury, clearly applied an erroneous test, which has no support in Wyoming law.
“IV. Whether the state failed to carry its burden of proof in regard to all the essential elements of the crime; specifically, there was not sufficient evidence to support a finding beyond a reasonable doubt of the mental sanity of the defendant.”
In answering these contentions, the State of Wyoming argues first that the issue of the defendant’s mental capacity was not withheld from the jury, and further that the trial court did not err in refusing to give the instructions on mental illness or deficiency and submit the form of verdict requested by the appellant.
With respect to Thelma Kind’s first contention, we must amplify her argument briefly. In part, § 7-ll-305(a), W.S.1977, relates to pleas and a sequential trial procedure with this latter aspect of the statute having been declared unconstitutional by this court in Sanchez v. State, Wyo., 567 P.2d 270 (1977). The last sentence then provides:
“In addition to other forms of verdict submitted to the jury, the court shall submit a verdict by which the jury may find the defendant not guilty by reason of mental illness' or deficiency excluding responsibility.” (Emphasis added.)
Thelma Kind argues that since this last sentence is phrased in mandatory fashion it requires the submission of the issue to the jury when a plea of not guilty by reason of mental illness or deficiency is entered. Thelma Kind overstates the thrust of this statute which, as enacted, did refer specifically to the hearing of evidence, even though the manner of doing so was disapproved in Sanchez, supra. In the absence of evidence submitted by a defendant in a criminal proceeding tending to establish mental illness or deficiency, a district court should not, despite the language of the statute, submit the issue of mental illness or deficiency to the jury simply on the basis of a plea of not guilty by reason of mental illness or deficiency.
Turning to the primary issue in this case, we previously have noted, although we did not recite in detail, the nature of the evidence which Thelma Kind presented with respect to mental illness or deficiency. While the form of our statute was changed in 1975, Ch. 191, S.L. of Wyo*963ming, 1975 1, the change did not alter the rule in Wyoming to the effect that once the defendant introduces evidence on the issue of mental responsibility the burden becomes that of the State to prove beyond a reasonable doubt that the defendant did not, as a result of mental illness or deficiency, lack substantial capacity either to appreciate the wrongfulness of his conduct or to conform his conduct to the requirements of law. State v. Sanchez, supra; Rice v. State, Wyo., 500 P.2d 675 (1972); Reilly v. State, Wyo., 496 P.2d 899 (1972), rehearing denied 498 P.2d 1236 (1972); Flanders v. State, 24 Wyo. 81, 156 P. 39 (1916), rehearing denied 24 Wyo. 81, 156 P. 1121 (1916); and State v. Pressler, 16 Wyo. 214, 92 P. 806, 15 Ann. Cas. 93 (1907). The evidence presented by the defendant in this case was ample to satisfy the requirement that she enter evidence of mental illness or deficiency, and it required the submission of that issue to the jury by the trial court. This is the basis of our reversal of this conviction.
The appellant suggests that the court below applied an erroneous test in concluding not to submit this issue to the jury. While the language of the trial judge in ruling upon the offered instructions well could lend itself to that conclusion, it also is susceptible to an interpretation that the trial judge was focused upon the matter of borderline mental retardation which was emphasized in the presentation of Thelma Kind’s evidence. The trial judge may, for that reason, have overlooked the other evidence of mental illness which was present in the record, and may have failed to respond to that evidence in ruling upon the offered instructions. Because of the presence of the other evidence of mental illness we do not decide in this case whether the evidence of mental retardation standing alone would have required the submission of the issue of mental responsibility to the jury. We must wait for a proper case to present that problem under our statute.
The appellant also contends that because of the failure of the State to go forward with evidence as to the mental responsibility of Thelma Kind, her Motion for Judgment of Acquittal should have been granted. She argues that the State may not rely upon a presumption of mental responsibility to meet evidence by the defendant on the issue. We agree with this argument of Thelma Kind. Since our statute does require the prosecution to prove the mental responsibility of the defendant beyond a reasonable doubt it is our conclusion that it is antithetical to that requirement to permit the prosecution to rely upon a presumption of sanity the effect of which is limited to excusing it from introducing evidence if the defendant introduces none.2 Once the defendant has offered evidence tending to show a lack of mental responsibility, the State then can rely only upon evidence which would show mental responsibility, and this is the manner in which it must meet its burden of establishing that element of its case beyond a reasonable doubt. Cf., Sanchez v. State, supra. See e. g., People v. Cochran, 313 Ill. 508, 145 N.E. 207 (1924), and Bradford v. State, 234 Md. 500, 200 A.2d 150, 17 A.L.R.3d 134 (1964). In this instance the record did contain evi*964dence in the defendant’s exhibits and in testimony elicited by the State from a defense witness from which mental responsibility at the time of the offense could be inferred. A jury issue was present under all the evidence.
The suggestion of the State that the issue of mental competence actually was submitted to the jury is of no avail here. It was submitted only in the form of advice that the jury could consider the mental capacity of the defendant in considering whether there was culpable neglect or criminal carelessness. This instruction did not in any way require proof of the additional element of mental responsibility by the prosecution. The difference between mental competence and mental responsibility is apparent and basic. Consequently the issue was not submitted.
Reversed and remanded for a new trial in accordance with the foregoing opinion.
ROSE, J., filed a partially concurring and partially dissenting opinion.
ROONEY, J., having recused himself from participation in this case, GUTHRIE, J., retired, was assigned, having been retained in active judicial service pursuant to § 5, Art. 5, Wyoming Constitution, and § 5-l-106(f), W.S.1977, by order of the court entered on January 1, 1979.
. Compare § 7-242(a), W.S.1957:
“(a) The prosecution shall prove beyond a reasonable doubt both the commission of the offense charged and the sanity of the defendant at the time of the commission of the offense; provided that the state shall be aided by the presumption that the defendant is sane until evidence to the contrary is presented; and the burden of first going forward and entering evidence of insanity shall be upon the defendant. The testimony of examining experts authorized in this act [§§ 7-239 to 7-243] shall be received either on behalf of the state or the defendant, under the rules of evidence applicable to criminal cases.”
with § 7-ll-305(b), W.S.1977:
“(b) The prosecution shall prove beyond a reasonable doubt all the elements of the offense charged and the mental responsibility of the defendant. However, every defendant is presumed to be mentally responsible and the burden of first going forward and entering evidence on the issue of mental responsibility is upon the defendant.”
. This was the rule prior to the 1975 amendment of the statute. Reilly v. State, Wyo., 496 P.2d 899 (1972). There is nothing to indicate that the legislature intended to change this rule when it amended the statute.