Well, a friend of Zimmerman's says the person calling for help was him, but witnesses who actually heard the cries said it sounded like a young boy and ceased abruptly after the shot was fired. I am sure that is a question that can be answered forensically.
And if I am not mistaken, it was a chilly, rainy night, and it does not take much chill for a person who lives in Miami to feel cold and want to be bundled up.