If credible, the woman's account could eventually shed some light on whether Zimmerman really killed the teen in self defense like he claims. So far, though, little has been released about what exactly she saw.
According to a report found amid in the newly public evidence, the woman spoke to special prosecutor Angela Corey's investigators somewhat reluctantly more than a month after the Feb. 26 killing. She had already talked to police detectives and a private investigator by that time.
A neighbor of Zimmerman's in the Retreat at Twin Lakes community in Sanford, Fla., her name is blacked out through most of the report. Prosecutors were ordered by the judge to keep all witness identities confidential. The name "Brett" appears twice in the document, but there is no way to tell for sure whether it is the woman's name.
She was interviewed by investigators Dale Gilbreath and T.C. O'Steen on April 4 at the Orlando offices of the attorneys she hired to represent her throughout the case.
From the start, the woman told them she was upset. She had given a written statement to a private investigator working for Martin's family, but she was under the impression it wouldn't be handed over to law enforcement. Now, authorities had it.
She told them she called 911 after hearing two men arguing loudly outside and then looked out to see them wrestling on the ground.
She heard "horrifying" calls for help and "agonizing yelps," but she could not tell which one was yelling. The woman said she saw one man on top of the other, moving in some sort of "side to side" motion and throwing no punches.
Zimmerman has said he was attacked and knocked to the ground by Martin, who then got on top of him and started slamming his head into the concrete beneath them.
While she was on the phone with 911, the woman said she heard a series of three pops. She thought a gunshot would be louder and she saw no flash of light like she expected, but the larger of the two men got up from the fight while the other remained on the ground. The summary of her interview does not say whether she believed the larger man had been the one on the top or bottom of the fight.
After the shooting, the larger man began to walk toward her window and she could see he was Hispanic, like Zimmerman. He put his hand up to his forehead as if he was looking into the distance.
The evidence released Thursday demonstrates that the woman's statement is the fullest account of the killing itself that prosecutors have outside of Zimmerman's own statements to police.
Other neighbors in the community heard the commotion or saw bits of the struggle, but no one else appears to have seen the shooting itself.
Still, the woman's version of events has a few discrepancies from the rest of the information public at this point.
For instance, authorities have said there was only one gunshot that night and that it hit Martin in the chest, killing him at the scene. The woman also said Zimmerman was wearing a short sleeve shirt, but in fact he was wearing an orange and black jacket as can be seen in photos police took after the shooting.
It's also clear the woman is jittery about talking about what she saw, hiring lawyers and hoping that at least one of her statements would never be given to authorities.
But the same woman may also have already spoken to the media. CNN's Anderson Cooper talked to someone in late March who claimed to be an eyewitness to the shooting.
At the time, it was impossible to verify the claims. The person refused to be shown on camera or give any details about his or her identify, including a gender. But what he or she said matched up fairly closely to what the woman told investigators in the newly released report. For example, the person told CNN that Zimmerman began to walk toward his or her window just after the shooting.
It's unclear how seriously prosecutors and defense attorneys are taking the woman. In the few court hearings that have been held about the case so far, her statements haven't come up.