(ABC News) A woman who was talking on the phone to Trayvon Martin moments before he was shot and killed by George Zimmerman acknowledged on the stand today that she does not know whether Zimmerman or Martin started the fatal fight.

The testimony of Rachel Jeantel, 19, was dissected over two days of often testy cross examination by Zimmerman’s lawyers in which she was challenged on her assertion that she heard Martin say “get off” just before he was shot.

Zimmerman, 29, is on trial for second degree murder in Martin’s death on Feb. 26, 2012. Martin, 17, was unarmed, but Zimmerman maintains he shot the teenager in self defense.

Jeantel, a key prosecution witness in the racially charged trial, testified that she was talking on the phone with Martin when he told her a “creepy ass cracker” was following him. She told defense lawyer Don West that “cracker” is how she referred to white people in her community.

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