It’s a judgment call, but the defense should inquire about how much time Trayvon spent with Sybrina (as compared to with Alica), and when was the last time she saw Trayvon alive.
“If they put her on the stand, I think cross will be brief or nonexistent.” Perhaps something like this:
Defense — Mrs. Fulton, were you in the courtroom during the testimony of the State’s audio expert, Dr. Nakasone?
SF — Yes.
Defense — Did Dr. Nakasone testify that it is impossible for anyone to identify who is screaming on the recording?
SF — Er uh er...
Defense — Would it refresh your memory for the recorder to read Dr. N’s testimony back to you?
SF — Er uh er...
Defense — Thank you. I withdraw the question. No further questions, Your Honor.