Is a person who aids and abets a crime even if someone else committed some or all of the criminal acts?

" 'All persons concerned in the commission of a crime, ... whether they directly commit the act constituting the offense, or aid and abet in its commission, ... are principals in any crime so committed.' [Citations.] Thus, a person who aids and abets a crime is guilty of that crime even if someone else committed some or all of the criminal acts. [Citation.] Because aiders and abettors may be criminally liable for acts not their own, cases have described their liability as 'vicarious.' [Citation.] This description is accurate as far as it goes. But ... the aider and abettor's guilt for the intended crime is not entirely vicarious. Rather, that guilt is based on a combination of the direct perpetrator's acts and the aider and abettor's own acts and own mental state." (People v. McCoy (2001) 25 Cal.4th 1111, 1116-1117, italics in original.)

A person aids and abets the commission of a crime when he, acting (1) with knowledge of the perpetrator's unlawful purpose, and (2) with intent or purpose of committing, encouraging, or facilitating the commission of the offense, (3) by act or advice aids, promotes, encourages or instigates the commission of the crime. (People v. Croy (1985) 41 Cal.3d 1, 11-12; People v. Beeman (1984) 35 Cal.3d 547, 561.) Direct evidence of the mental state is rarely available and may be shown with circumstantial evidence. (People v. Beeman, supra, at pp. 558-559.)