What is the test for an aider and abettor of a crime?

As discussed, under the natural and probable consequences doctrine, "a person who aids and abets a confederate in the commission of a criminal act is liable not only for that crime (the target crime), but also for any other offense (nontarget crime) committed by the confederate as a 'natural and probable consequence' of the crime originally aided and abetted." (People v. Prettyman, supra, 14 Cal.4th at p. 254.) Accordingly, to convict a defendant of a nontarget crime as an aider and abettor, the jury must find that the defendant assisted or encouraged the commission of a target crime, a confederate committed an offense other than the target crime, and the nontarget offense committed by the confederate was a natural and probable consequence of the target crime that the defendant assisted or encouraged. (Ibid.) "[T]he jury need not unanimously agree on the specific target crime that the defendant aided and abetted. . . . Nevertheless, at trial each juror must be convinced, beyond a reasonable doubt, that the defendant aided and abetted the commission of a criminal act, and that the offense actually committed was a natural and probable consequence of that act." (Id. at pp. 267-268.) The instructions to the jury must accurately "describe[e] each step in this process [to] ensure proper application by the jury of the 'natural and probable consequences' doctrine." (Id. at p. 267.)