¶1dissenting.
¶2Appellant testified that he was “frightened” by the decedent’s actions just prior to the shooting. In order to support his claim of self-defense, appellant attempted to place the testimony of two expert witnesses before the jury. These witnesses were Dr. Albert Leavitt, Chief Psychologist of the Philadelphia Court of Common Pleas, and Dr. Kenneth Kool, M. D., a professional psychiatrist. Both had examined appellant prior to trial, and both were prepared to testify concerning appellant’s state of mind at the time of the shooting. According to the offer of proof placed on the record by appellant’s trial counsel, Dr. Leavitt would have testified that appellant was pathological and suffered from organic deficiencies which had accrued over time due to his heavy alcohol intake and perhaps also to poor diet; Dr. Leavitt would have stated that appellant was paranoid and overly suspicious, but that he would not actively look for trouble or confrontation. If he were threatened, however, his paranoid condition would be heightened, and he would assume a defensive posture, seeking out “concrete” and “tangible” means of defending himself, as opposed to seeking assistance from a third party or the authorities. Dr. Kool would have corroborated Dr. Leavitt’s diagnosis.
¶3The purpose of the testimony of these two psychiatric experts was to aid the jury in making a determination of appellant’s state of mind at the time of the shooting. The psychiatric testimony was designed to help the jury to *60understand appellant’s perception of the events leading up to the shooting, and based on that understanding of appellant’s subjective mental state, to determine whether or not this appellant acted reasonably under the circumstances.
“It is for the jury to decide whether the defendant’s belief was reasonable. Such a determination must be based on the facts and circumstances as the defendant perceived them. This they were unable to do because psychiatric testimony concerning the defendant’s state of mind and its effect on his perception of the facts and circumstances that immediately preceded the shooting was withheld from the jury.” Commonwealth v. Light, 458 Pa. at 340-341, 326 A.2d at 295 (Dissenting Opinion of Manderino, J., joined by Roberts, J., and Nix, J.)
¶4The issue presented in this case is not whether some unreal perfect being acted reasonably but whether a human being acted reasonably. The proper statement of the issue is necessary to its .proper resolution. Sane human beings vary greatly in their reasonable reactions to situations with which they are confronted. The jury, therefore, should be entrusted with the decision as to a particular defendant. The justice of a particular situation cannot be ascertained as a matter of law.
¶5As stated in Commonwealth v. Light, 458 Pa. 328, 340, 341, 326 A.2d 288, 295 (1974) (Dissenting Opinion of Manderino, J., joined by Roberts, J., and Nix, J.):
“It is easy to imagine situations where* two different people could, because of differences in their subjective states of mind ‘reasonably’ react in totally different ways to the same stimulus. For example, one who, confronted on a sidewalk by a growling dog, reacts in terror because of a subjective fear of animals, is no less reasonable (based on the facts as he perceives them) in his belief that the dog is about to attack than another who, because of years of training as a veterinarian and experience in handling dogs, sees that (based on the facts as he perceives them) there is no danger. (Emphasis in original.)
¶6*61The jury must therefore consider the circumstances as perceived by the defendant when determining the reasonableness of the defendant’s belief that he was in imminent danger of death or serious bodily harm. Psychiatric evidence as to a defendant’s state of mind immediately prior to the killing is relevant because it aids the jury’s understanding of the defendant’s perception of the circumstances preceding the slaying.
¶7In Murray v. Commonwealth, 79 Pa. 311, 317 (1875), it was said,
“It is not necessary that a man shall be in actual imminent peril of life, or great bodily harm before he may slay his assailant. It is sufficient if in good faith he has a reasonable belief founded upon the facts as they appeared to him at the time, that he is in imminent peril, even though it should afterwards appear that he was mistaken.” (Emphasis added.)
¶8The jury should decide the reasonableness of defendant’s belief that he was in imminent danger of death or serious bodily harm. The majority, however, says that the exclusion of relevant evidence such as that offered here was not error because, even if the psychiatric testimony had been admitted, “ . . . the record failed to establish as a matter of law a valid claim of self-defense.” (Majority opinion at p. 50.) I dissent.
¶9The majority’s analysis implies that the defendant in a homicide case must “establish” a self-defense claim. Our recent cases clearly indicate that once the possibility of a defense of self-defense has entered the case (regardless of the source of that possibility), the prosecution must prove beyond a reasonable doubt that the accused was not acting in self-defense at the time of the slaying in order for the conviction to be sustained. Commonwealth v. Walley, 466 Pa. 363, 353 A.2d 396 (1976); Commonwealth v. Cropper, 463 Pa. 529, 345 A.2d 645 (1975). To negate the claim of self-defense the prosecution must show that at least one of the elements of that defense was absent. Therefore, it is necessary for the prosecution to establish either that the *62defendant did not subjectively believe that he was in imminent peril of death or serious bodily harm, or if such belief was, in fact, held, the prosecution may negate the defense by proving beyond a reasonable doubt that that belief was unreasonable under the circumstances. Also, the prosecution could prevail by establishing that the slayer was not free from fault in provoking or continuing the incident which resulted in the slaying, or, the prosecution could meet its burden by showing beyond a reasonable doubt that the slayer had a duty to retreat or to avoid the danger and that he or she had the opportunity to do so but elected not to. See Commonwealth v. Myrick, 468 Pa. 155, 360 A.2d 598 (1976); Commonwealth v. Cropper, supra,463 Pa. 529, 345 A.2d 645 (1975).
¶10To state that “. . . the record failed to establish as a matter of law a valid claim of self-defense . . . ” therefore misconceives the nature of the problem. The question which must be answered is whether the prosecution has established beyond a reasonable doubt that the defendant was not acting in self-defense at the time the homicide was committed. Evidence of the defendant’s state of mind is relevant to the jury’s determination of that issue and, as conceded by the majority, its exclusion is therefore error. Contrary to the assertion of the majority, however, the exclusion of the evidence at issue in the instant case cannot be considered harmless because we, as an appellate court, cannot say beyond a reasonable doubt that the jury would have arrived at the same result had they heard it. The proffered testimony was such that it could have created a reasonable doubt in the jury’s collective mind as to whether the prosecution had established all the elements of the charge beyond a reasonable doubt. It could have, for example, created a reasonable doubt as to whether appellant acted with malice, for if he believed he was in imminent danger, he could not have acted maliciously. It could also have created a reasonable doubt as to the prosecution’s claim that such a belief was unreasonable under the circumstances. Furthermore, it had relevance concerning the question *63of provocation, and could have allowed the jury to acquit by creating a reasonable doubt as to whether appellant, as claimed by the prosecution, provoked the incident which resulted in the slaying.
¶11For these reasons I would reverse the judgment of sentence and remand for a new trial.