What is the legal test for direct aiding and abetting in a murder case?

"[A]n aider and abettor's mental state must be at least that required of the direct perpetrator.... 'When the offense charged is a specific intent crime, the accomplice must "share the specific intent of the perpetrator"; this occurs when the accomplice "knows the full extent of the perpetrator's criminal purpose and gives aid or encouragement with the intent or purpose of facilitating the perpetrator's commission of the crime." [Citation.]' [Citation.]" (People v. McCoy (2001) 25 Cal.4th 1111, 1118, italics added, fn. omitted.)

"Aiders and abettors may ... be convicted of first degree premeditated murder based on direct aiding and abetting principles. [Citation.] Under those principles, the prosecution must show that the defendant aided or encouraged the commission of the murder with knowledge of the unlawful purpose of the perpetrator and with the intent or purpose of committing, encouraging, or facilitating its commission. [Citation.] Because the mental state component - consisting of intent and knowledge - extends to the entire crime, it preserves the distinction between assisting the predicate crime of second degree murder and assisting the greater offense of first degree premeditated murder. [Citations.] An aider and abettor who knowingly and intentionally assists a confederate to kill someone could be found to have acted willfully, deliberately, and with premeditation, having formed his own culpable intent. Such an aider and abettor, then, acts with the mens rea required for first degree murder." (People v. Chiu (2014) 59 Cal.4th 155, 166-167.)

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