Legal Question in Constitutional Law in California

At the point that a person knows that he is helping another person in the commission of a crime which includes escaping from the scene of the crime that person becomes an accessory after the fact. If the person was aware before the crime is committed then they are an accessory in fact to the commission of the crime.

The person you describe would not be an accessory if she didn't know about the crime when she drove the criminal home. But she could still be charged if it *appeared* to prosecutors that she knew. And she could even be convicted if a jury was convinced beyond a reasonable doubt that she knew. The result would not be correct, but such things do happen.