In People v. Zermeno (1999) 21 Cal.4th 927, the California Supreme Court held that proof another gang member aided and abetted an assault with a deadly weapon committed by the defendant, and for which the defendant was then on trial, could not be used with defendant's conduct to establish the necessary pattern of criminal activity. The court concluded the act of aiding and abetting an assault with a deadly weapon and the assault itself qualified as but one offense, and thus there was insufficient evidence of the requisite two predicate offenses. (Id. at p. 932.) This conclusion was compelled by the nature of an aider and abettor's criminal liability, which is solely vicarious, and the statutes which discussed an aider and abettor's liability by references to the commission of "a crime," or "the offense" which are singular terms. "Thus, both statutes Pen. Code, 971 and 31 describe aider and abettor liability as involving a single offense, the one committed by the perpetrator." (People v. Zermeno, supra, at p. 932.)