Is a person who aids or abets a crime liable for the crime if the original crime was committed independently by another person?

As referenced above, principals to crime (that is, those who are equally responsible for its commission) include not only the actual perpetrator of the crime but one who aids or abets its commission. One can aid or abet by being present and assisting at the time of the crime (People v. Villa (1957) 156 Cal.App.2d 128, 133, 318 P.2d 828) or, if not present at the time of commission, by advising or encouraging its commission. ( 31.) One who aids and abets a crime is liable not only for a crime committed in accordance with the advice and encouragement given, but also for any other crime the perpetration of which by the direct actor was the natural and probable consequence of the criminal act encouraged. (People v. Durham (1969) 70 Cal.2d 171, 181, 74 Cal.Rptr. 262, 449 P.2d 198.) One may therefore become criminally liable for a crime committed independently by another (either within or outside the presence of the aider and abettor) if the original crime jointly contemplated could reasonably lead to the crime perpetrated. In such situation the aider and abettor's guilt is based not on his own actions, but on the actions of his partner in crime. The aider and abettor's liability is thus "derivative." As explained by Professor Kadish in "Complicity, Cause and Blame: A Study in the Interpretation of Doctrine" (1985) 73 Cal.L.Rev. 323, 337: