(dissenting)—I dissent. Crane's right to jury unanimity was violated by the trial court's failure to give a Petrich instruction. State v. Petrich, 101 Wn.2d 566, 570-*33672, 683 P.2d 173 (1984) provides that, when the State has presented evidence of several criminal acts in support of a single criminal charge, either the State must elect the act upon which it will rely for conviction or the court must instruct the jury to reach a consensus as to the act upon which its guilty verdict is based. Without such specification, there can be no guaranty of jury unanimity.
In the instant case, the State presented evidence of several incidents occurring between May 9 through May 15 which could have been the cause of Steven Collins' death. These included Steven being beaten with plastic toys such as those found in the Crane apartment, being severely shaken, and possibly being thrown against a wall or from a car. Because the State did not specify to the jury which act it was relying upon to support its murder charge, the trial court's failure to require jury unanimity requires reversal of Crane's second degree murder conviction.
Analysis
Judge Grosse summarized the holding of the Court of Appeals reversing Crane's second degree murder conviction, with which I concur, as follows:
We are compelled to follow the rationale of Petrich, a case where the State proved multiple acts of sexual abuse. Here, the State was required to prove second degree assault causing blunt trauma to the head. It presented evidence of several assaults occurring from May 9 through May 13, any one of which could have caused the trauma and thus supported the conviction. We are not certain that the jurors unanimously agreed on one of the assaults in convicting Crane of second degree murder.
(Italics mine.) State v. Crane, cause 20670-2-1 (Dec. 4, 1989), slip op. at 6-7. State v. Crane, noted at 56 Wn. App. at 1019 (1989).
A defendant may be convicted only when a unanimous jury concludes the criminal act charged has been committed. Petrich, 101 Wn.2d at 569.
[WJhere the evidence tends to show two separate commissions of the crime, unless there is an election it would be impossible to know that either offense was proved to the *337satisfaction of all of the jurors beyond a reasonable doubt. The verdict could not be conclusive on this question, since some of the jurors might believe that one of the offenses was so proved and the other jurors wholly disbelieve it but be just as firmly convinced that the other offense was so proved. The greater the number of offenses in evidence, the greater the possibility, or even probability, that all of the jurors may never have agreed as to the proof of any single one of them. . . . [T]he proper course in such a case, after the evidence is in is to require the state to elect which of such acts is relied upon for a conviction.
Petrich, at 570 (quoting State v. Workman, 66 Wash. 292, 294-95, 119 P. 751 (1911)). If the State does not make such an election, it is the court's responsibility to instruct the jury that "all 12 jurors must agree that the same underlying criminal act has been proved beyond a reasonable doubt," Petrich, 101 Wn.2d at 572, to protect the defendant's right to jury unanimity. If the jury is not properly instructed, the error will be deemed harmless only if no rational trier of fact could have entertained a reasonable doubt that each incident established the crime beyond a reasonable doubt. State v. Kitchen, 110 Wn.2d 403, 405-06, 756 P.2d 105 (1988).
In the instant case, the State presented medical evidence that Crane assaulted Steven Collins on several occasions between May 9 and May 15. The State made the following charge against Crane in an information:
COUNT I: SECOND DEGREE MURDER, committed as follows: That the defendant, on or between May 9, 1986 and May 15, 1986, while committing and attempting to commit the crime of second degree assault, and in the course of and in furtherance of said crime and in immediate flight therefrom, did cause the death of Steven Collins, a human being, not a participant in such crime, said death occurring on or about the 17th day of May, 1986; proscribed by RCW 9A.32.050(1)(b), a felony.
(Italics mine.) Clerk's Papers, at 65. The trial court gave the jury an instruction which read in relevant part:
To convict the defendant David Crane of the crime of murder in the second degree as charged in Count I each of the following elements of the crime must be proved beyond a reasonable doubt:
*338(1) That Steven Collins died on May 17, 1986;
(2) That on or between the 9th and 15th day of May, the defendant committed the crime of second degree assault by knowingly inflicting grievous bodily harm upon Steven Collins by causing Steven Collins to sustain massive blunt trauma to the head;
(3) That the defendant caused the death of Steven Collins in the course of and in furtherance of such crime;
(Italics mine.) Clerk's Papers, at 28. Because the jury was never instructed to consider only the assault occurring on May 15 when deliberating as to the second degree murder charge, we are left with the possibility that some jurors believed one incident, perhaps a beating with the plastic tools, caused Steven's death, while another believed a different incident, perhaps a severe shaking, was the cause. If this was the case, there was a lack of unanimity on all of the elements necessary for a valid conviction. Petrich, 101 Wn.2d at 572; State v. Workman, 66 Wash. 292, 294-95, 119 P. 751 (1911). Because there is no way to establish this was not the case, Crane's conviction must be reversed.
Moreover, the failure to give a Petrich instruction was not harmless error unless no rational trier of fact could have had a reasonable doubt that each incident established the crime beyond a reasonable doubt. Kitchen, at 405-06 (modifying the Petrich harmless error standard). This approach presumes that the error was prejudicial. Kitchen, at 411.
As the Court of Appeals notes, the failure to give a Pet-rich instruction was not harmless in the instant case. Crane is charged with second degree murder. If no rational juror could have reasonably doubted that each assault committed between May 9 and May 15 caused the death of Steven Collins, the error was harmless. In other words, each assault must have been indispensable to Steven Collins' death.
The evidence presented at trial did not clearly establish that each episode of abuse between the 9th and the 15th was necessary to Steven Collins' death; rather, the medical testimony indicated the assault that caused the boy's death likely occurred on May 15, the afternoon he was taken to *339the hospital. Still, the jury was instructed to determine whether an assault resulting in Steven Collins' death occurred on or between May 9 and May 15, after hearing testimony that Steven might have been beaten or thrown by Crane prior to May 15. Thus, although the medical evidence indicated otherwise, the jury was free to, and in fact was instructed to, consider whether perhaps an earlier beating with plastic tools or being thrown before May 15 resulted in the boy's death. For these reasons, the Court of Appeals reached the following conclusion:
Because the evidence was largely circumstantial as to each assault we conclude that the error was not harmless; that a rational trier of fact could have a reasonable doubt as to whether Crane assaulted Steven with plastic tools, shook him, or threw him against a wall or out of a car. Without a Petrich instruction Crane was denied a fair trial [,] and we must reverse the judgment and sentence for second degree murder.
State v. Crane, supra, slip op. at 8-9. I agree with the court's conclusion. The trial court's failure to give a Petrich instruction was not harmless error.
The majority unfairly criticizes the Court of Appeals opinion as relying on factual determinations which do not reflect the evidence presented at trial in concluding Petrich requires an instruction in this case. Majority, at 328-30. In fact, the application of Petrich to this case was irreversibly determined at the trial rather than the appellate level by the State's charging of murder based on acts occurring between May 9 and 15, instead of just on the 15th; by the State introducing circumstantial evidence that assaults occurred other than on the 15th; and by the court's instruction to the jury to consider acts occurring between the 9th and 15th as possibly resulting in Steven Collins' murder. At this point, Petrich required that the State either indicate which act it was relying upon or the court to instruct the jury to unanimously agree on the act which caused the death. Neither was done.
The majority states that the Court of Appeals incorrectly concluded from the testimony that each alleged assault actually occurred and, therefore, Petrich required that the *340jurors unanimously agree which one caused the death. Majority, at 328. The court made no such conclusion and, in fact, states on page 8 of its opinion that the evidence as to the various assaults was largely circumstantial. The point made by the Court of Appeals was that the State's mere introduction of evidence of other assaults, when combined with the instruction to consider the time period between May 9 and May 15, permitted each juror to make his own decision as to which assault resulted in the death of Steven Collins. Without the aid of a Petrich instruction, the verdict violated Crane's right to jury unanimity.
The majority further unfairly criticizes the Court of Appeals opinion because, "[wjhile the evidence does support that several assaults occurred during the charging period, it does not support the court's conclusion that any one of them could have led to the child's death." (Italics omitted.) Majority, at 329. Again, the relevant inquiry is whether the jury was permitted to consider more than one act or incident as the basis for the murder charge. The jury instruction clearly permitted—in fact, invited—the jury to do just that. Regardless of whether the State based its entire case on the assault occurring on the 15th, and regardless of whether the medical experts agreed that the fatal injuries would have probably rendered the child unconscious within minutes, the important thing is the jury was permitted to consider more than one act as the basis for its conviction for second degree murder. Had the State told the jury to rely only on the assault on the 15th, or had the court instructed the jury to agree which assault caused the death, Crane's right to jury unanimity would not have been violated. This did not happen. The error is presumed prejudicial unless no rational juror could reasonably doubt but that each assault beyond a reasonable doubt resulted in the second degree murder. As already discussed, such was clearly not the case here.
*341The majority avoids the Petrich jury instruction requirement by relying on the "continuous conduct" exception to Petrich. Majority, at 330. Under this exception, a continuing course of conduct may form the basis of one charge in an information. 101 Wn.2d at 571. The majority applies this rule to the time between 3 and 5 p.m. on May 15, "the most logical period of time when the fatal injuries were inflicted". Majority, at 330. This exception is inapplicable here where the jury was presented with evidence of assaults which occurred over a 6-day period and instructed to consider this 6-day period in its deliberations. The instruction to consider all 6 days could not have been harmless, as the majority determines at page 331, especially when combined with the evidence of other assaults the State voluntarily introduced.
Moreover, the evidence did not, as the majority indicates, establish conclusively that the fatal injury was inflicted on May 15. Although the doctors agreed that the injury more likely than not occurred that day, Dr. Feldman testified that, given Steven's abnormal behavior in the days before his death (he acted lethargic, withdrawn, and frightened and did not have his usual appetite), it was possible, but highly unlikely, that a blow received before the 15th had resulted in a slow deterioration. In light of this, was the jury to determine, in the face of being told otherwise by the judge, that it was not to consider evidence of other assaults occurring between the 9th and 15th? The failure to give a Petrich instruction is presumed prejudicial. It was clearly so here.
Conclusion
Crane was entitled to a Petrich instruction to protect his right to jury unanimity, which was not given. The failure to give the Petrich instruction was prejudicial error. Consequently, Crane was denied a fair trial, and his second degree murder conviction must be set aside.
*342I would affirm the Court of Appeals decision reversing defendant's second degree murder conviction.
Utter, J., concurs with Dore, C.J.