I have an idea what witness this might be.
There was a woman who called 911 to report the altercation. This is the call on which you can hear the gunshot in the background. You can also hear her yelling at someone else in the house telling them NOT to go out and help the person who was screaming for help.
One of the networks had an interview with this woman with her appearance and voice disguised. She said she peeked out the window and talked about the larger man being on top and hearing the cries for help.
The news media reported this as a grown man killing a young boy.
So everyone who didn't personally examine the body was under the impression that the young boy was the smaller person and had the higher-pitched voice. This was compounded by the photos of 12-year-old Trayvon being used by the media.
In fact, Zimmerman is only 5'8" and was the smaller man by several inches. Zimmerman also has a high-pitched voice even when he is not screaming, as anyone can hear on the recording of the police dispatcher call.
So we may have here a situation in which witnesses have interpreted what they heard or saw by reference to the mis-reporting in the media, leading them to believe they know the opposite of what occurred.
It was the woman who appeared twice on CNN. Cboldt and Maggie had her number the first time she appeared with AC.
She came back later because she had new evidence...
Sounded like a “valley girl” to me.