What is the test for an aider and abettor to be held responsible for assisting and assisting in the crime?

Mendoza (1998) 18 Cal.4th 1114, 1122.) "The actual perpetrator must have whatever mental state is required for each crime charged, . . . An aider and abettor, on the other hand, must 'act with knowledge of the criminal purpose of the perpetrator and with an intent or purpose either of committing, or of encouraging or facilitating commission of, the offense.' [Citation, original italics.]" (Id. at p. 1123.) An aider and abettor "may be held criminally responsible as an accomplice not only for the crime he or she intended to aid and abet (the target crime), but also for any other crime that is the 'natural and probable consequence' of the target crime." (People v. Prettyman (1996) 14 Cal.4th 248, 261.)

As our high court has stated, "the doctrine enunciated in People v. Beeman (1984) 35 Cal.3d 547, 554-555 . . . , that one may be liable as an aider and abettor 'when he or she aids the perpetrator of an offense, knowing of the perpetrator's unlawful purpose and intending, by his or her act of aid, to commit, encourage, or facilitate commission of the offense, "snares all who intentionally contribute to the accomplishment of a crime in the net of criminal liability defined by the crime, even though the actor does not personally engage in all of the elements of the crime." [Citation.]' [Citation.] Aiding and abetting does not require participation in an agreement to commit an offense, but merely assistance in committing the offense. [Citation.]" (People v. Morante (1999) 20 Cal.4th 403, 433.)