What is the test for a jury to determine whether each aider and abettor personally acted with malice?

In arguing that the instructions were flawed because they did not require the jury to determine "whether each aider and abettor personally acted with malice and a willful, premeditated and deliberated intent to kill," Sanchez relies primarily on People v. McCoy (2001) 25 Cal.4th 1111 (McCoy). In McCoy, the court explained that "outside of the natural and probable consequences doctrine, an aider and abettor's mental state must be at least that required of the direct perpetrator" in order for the aider and abettor to be vicariously liable. (Id. at p. 1118.) Thus, when the charged offense is murder, "the aider and abettor must know and share the murderous intent of the actual perpetrator." (Ibid.) "Aider and abettor liability is premised on the combined acts of all the principals, but on the aider and abettor's own mens rea." (Id. at p. 1120, italics added.)⁹