I'm not watching it, but if she is the girl, with whom Martin was speaking on the phone just before her death, I've always thought she is the most crucial witness of the case. Her statements to the police came before she knew Zimmerman's account, and her testimony will offer the best evidence of Martin's state of mind at the time of the altercation that resulted in his death. If the jury believes that Zimmerman initiated or provoked the confrontation, they can not consider his argument of self-defense. Conversely, if the jury believes Martin initiated the confrontation, then they can consider whether self-defense applies.