Is there insufficient evidence supporting her conviction of torture murder?

Defendant asserts first degree murder by torture requires torture to be the sole cause of death, and therefore claims there was insufficient evidence supporting her conviction of torture murder. She relies on the following statement found in People v. Johnston (1957) 48 Cal.2d 78; " 'An essential element of murder by torture is that the acts of torture must be the cause of death of the victim.' " (Id. at p. 89, italics added.) That statement, however, was part of the court's quotation of the jury instructions, not part of the court's holding. Indeed, whether the torture was "a" cause of death or "the" cause of death was not an issue in that case.