Can a jury return a guilty verdict on a charge of murder if it finds concurrent causes of death, even if the criminal act was not a principal cause of death?

Defendant claims that these instructions misstated the law by permitting the jury to return a guilty verdict on a charge of murder if it found concurrent causes of death, even if the criminal act was not a principal cause of death. The law provides, however, that as long as the jury finds that without the criminal act the death would not have occurred when it did, it need not determine which of the concurrent causes was the principal or primary cause of death. Rather, it is required that the cause was a substantial factor contributing to the result: "`[N]o cause will receive judicial recognition if the part it played was so infinitesimal or so theoretical that it cannot properly be regarded as a substantial factor in bringing about the particular result.'" (People v. Caldwell (1984) 36 Cal.3d 210, 220, 203 Cal.Rptr. 433, 681 P.2d 274; see also In re M.S. (1995) 10 Cal.4th 698, 719-720, 42 Cal. Rptr.2d 355, 896 P.2d 1365.)