*222 Opinion
George F. Ladd, claimant to the heirship in the estates of James Noel Ladd and John Christopher Ladd, appeals from an order determining that Gloria B. Ladd (respondent) is the sole heir of both decedents.
Gloria Ladd killed her two teenaged sons, James and John. Appellant concedes that the motivation for the killings was that respondent was contemplating suicide and “didn’t want them upset by being homeless orphans and other trauma that goes with suicide.” Respondent was charged with murder (Pen. Code, § 187) and pleaded not guilty and not guilty by reason of insanity. A judge sitting without a jury found her guilty of murder in the first degree, and insane at the time of the commission of the offense. Upon a further finding that respondent had not recovered her sanity, the court rendered judgment committing her to a state hospital for treatment. (See Pen. Code, § 1026.)
James and John died intestate. The administrator of their estates petitioned the court for an order determining heirship. (Prob. Code, § 1080.) The superior court determined that respondent is the sole heir to the estates of her two sons. (Prob. Code, § 225.) This appeal by a paternal uncle of James and John challenges the order.
Appellant contends that respondent is barred from inheriting decedents’ estates by Probate Code section 258, which provides in part: 1 “No person who has unlawfully and intentionally caused the death of a decedent. . . shall be entitled to succeed to any portion of the estate or to take under any will of the decedent. ... A conviction or acquittal on a charge of murder or voluntary manslaughter shall be a conclusive *223 determination of the unlawfulness or lawfulness of á causing of death, for the purposes of this section.”
The laws of inheritance and testamentary disposition are wholly statutory and subject to legislative control, and do not depend on the ideas of the courts as to justice and natural rights. (See
Estate of Kirby
(1912)
The language and legislative history of section 258 are relevant to determine the Legislature’s intent. (See generally
Estate of McGowan
(1973)
The Legislature made several changes in 1963. (See generally
Probate Code
(1963) 38 State Bar I. 769.) The reference to a person “convicted of the murder or voluntaiy manslaughter of the decedent” was changed to a person “who has unlawfully and intentionally caused the death of a decedent.” This amendment was perhaps designed for the murder-suicide cases. (See
Estate of McGowan, supra,
For purposes of section 258, the Legislature classified persons who are accused of causing the death of a decedent into four categories:
1. If the person has not been convicted or acquitted of murder or voluntary manslaughter, the probate court must determine whether or not the claimant “unlawfully and intentionally” caused the death of a decedent to decide whether or not section 258 terminates the claimant’s inheritance rights. (See
Estate of Kramme, supra,
2. If a person is acquitted of murder or voluntaiy manslaughter, the acquittal is a conclusive determination that the person did not “unlawfully and intentionally” cause the death of the decedent and section 258 does not terminate the claimant’s inheritance rights. (See
Wilson
v.
Wilson, supra,
3. If a person is convicted of murder or voluntary manslaughter, the conviction is a conclusive determination that the person “unlawfully and intentionally” caused the death of a decedent, and section 258 terminates his or her inheritance rights.
*225 4. If a person caused the death of a decedent in the perpetration of or attempt to perpetrate certain specified felonies, the person is not entitled to an interest in the decedent’s estate.
Inferably, the Legislature based these classifications on the mental state or culpability of the person who caused the death of a decedent, or on the punitive value of section 258. (Cf.
People
v.
Holt
(1944)
Respondent pleaded not guilty and not guilty by reason of insanity to a charge of first degree murder. By stipulation the two pleas were tried together (cf. Pen. Code, § 1026). The plea of guilty was decided first; respondent was presumed sane at this guilt phase. The trial court determined that respondent was guilty of first degree murder. This finding did not constitute a “conviction” of murder for purposes of section 258. The word “conviction” has several meanings in California law. (See
Helena Rubenstein Internat.
v.
Younger
(1977)
It is reasonable to conclude that the Legislature intended that this judgment constitute an “acquittal” for purposes of section 258. First, the California courts refer to a judgment entered after a finding of insanity as an acquittal. (See, e.g.,
People
v.
Drew
(1978)
This conclusion, that the Legislature intended that a judgment after a finding of insanity constitute an acquittal for purposes of section 258, is bolstered by a review of the insanity and diminished capacity defenses. A finding of diminished capacity or of insanity is a conclusion drawn from evidence of a defendant’s mental condition.
(People
v.
Wetmore
(1978)
*227
A criminal defendant charged with murder or voluntary manslaughter could raise the diminished capacity defense to establish that he did not form the mental state necessary to commit the offense. If successful, the defendant could be acquitted of the higher offense and convicted of involuntary manslaughter. (See
People
v.
Ray
(1975)
We conclude that section 258 does not preclude inheritance by respondent from her sons.
Appellant also contends that he is entitled to an interest in decedents’ estates under Probate Code section 229, subdivision (b),
4
and that the trial court erred when it determined that respondent was the sole heir under Probate Code section 225.
5
The burden of proof was on appellant to establish that he was entitled to an interest in decedents’ estates under section 229.
(Estate of Westerman
(1968)
The judgment is affirmed.
Notes
Probate Code section 258 provides in its entirety: “No person who has unlawfully and intentionally caused the death of a decedent, and no person who has caused the death of a decedent in the perpetration or attempt to perpetrate arson, rape, robbery, burglary, mayhem, or any act punishable under Section 288. Penal Code, shall be entitled to succeed to any portion of the estate or to t#ke under any will of the decedent; but the portion thereof to which he would otherwise be entitled to succeed goes to the other persons entitled thereto under the provisions of this chapter or under the will of the decedent. A conviction or acquittal on a charge of murder or voluntary manslaughter shall be a conclusive determination of the unlawfulness or lawfulness of a causing of death, for the purposes of this section.”
‘A person is not responsible for criminal conduct if at the time of such conduct as a result of mental disease or defect he lacks substantial capacity either to appreciate the criminality [wrongfulness] of his conduct or to conform his conduct to the requirements of law.’"
“First, was the accused because of a diminished capacity unaware of a duty to act within the law? . . . Second, even assuming that the accused was aware of this duty to act within the law, was he. because of a diminished capacity, unable to act in accordance with that duty?” (Id., at p. 758; see also id., at p. 760 [“a person’s ability to conform his conduct to that comprehended duty”].)
Probate Code section 229, subdivision (b), provides: “If the decedent leaves neither issue nor spouse, that portion of the estate created by gift, descent, devise, or bequest from the separate property of a parént or grandparent shall go to the parent or grandparent who made such gift, devise, or bequest or from whom the property descended, or if such parent or grandparent is dead, such property shall go in equal shares to the heirs of such deceased parent or grandparent.”
Probate Code section 225 provides: “If the decedent leaves neither issue nor spouse, the estate goes to his parents in equal shares, or if either is dead to the survivor, or if both are dead in equal shares to his brothers and sisters and to the descendants of deceased brothers and sisters by right of representation.”
