To be found guilty under a theory of aiding and abetting, the defendant generally must know of the direct perpetrator's criminal purpose, must intend to aid and abet the perpetrator, and must do or say something that in fact aids and abets the crime.
Someone who aids and abets a crime is generally just as guilty as the direct perpetrator. This is true whether the aider and abettor had a minor role in the crime or was the most culpable person.
Examples of aiding and abetting include someone who is a lookout, who drives the getaway car, or who stays with the direct perpetrator during the crime as show of force or to help give the direct perpetrator courage to commit the crime.
An aider and abettor can also be someone who orders the direct perpetrator to commit the crime (like a senior gang member directing a junior gang member to commit a crime).
The aider and abettor does not need to be present when the crime occurs. On the flip side, mere presence at the scene of a crime, standing alone, is not enough to find someone guilty as an aider and abettor.
If someone only helps the direct perpetrator after the crime has been completed, such as by hiding the person, or destroying or disposing of evidence, that person is an accessory after the fact, not an aider and abettor.
If someone intends to aid and abet one crime, but a different crime occurs, the aider and abettor may still be guilty of that other crime, if the other crime was reasonably foreseeable under the circumstances. This is called the natural and probable consequences doctrine.
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