What are the remaining contentions in defendant's defence of involuntary manslaughter under section 192 of the California Penal Code?

We turn now to defendant's remaining contentions, which relate to the correctness of the referee's findings. Defendant first contends the referee erred in finding he violated section 192 of the Penal Code because the People failed to show beyond a reasonable doubt either that he had an intent to commit manslaughter, or was guilty of criminal negligence. For this assertion he relies on Penal Code section 20 and People v. Stuart (1956) 47 Cal.2d 167, 302 P.2d 5. Section 20 provides, in relevant part, 'In every crime or public offense there must exist a union, or joint operation of act and intent, or criminal negligence.' Applying this section, we held in Stuart that a pharmacist who sold a lethal drug could not be convicted of involuntary manslaughter under Penal Code section 192, subdivision (2)--a killing in the commission of a misdemeanor--absent evidence of criminal negligence.