Does the crime scene need to be sufficient to establish "act tending to demonstrate aiding and abetting"?

crime scene does not suffice to establish aiding and abetting, acts tending to demonstrate aiding and abetting include "presence at the scene . . . , companionship, and conduct before and after the crime, including flight." (People v. Haynes (1998) 61 Cal.App.4th 1282, 1294.) A lookout need not signal a warning to be found culpable, because his presence facilitates the crime in other ways, serving as "encouragement to his companions and . . . a deterrent [to citizens who might interfere with the criminal activity]." (People v. Moore (1953) 120 Cal.App.2d 303, 306.) Here, evidence was presented that the men at the bus stop were close by and left the scene with the perpetrators. One of them carried a backpack consistent with the one found with defendants containing stolen property. The jury could reasonably infer that Medina acted as a lookout and deterrent, fled the scene with the carjackers, and provided the backpack to hide stolen goods. Substantial evidence supports his guilt.