SANFORD, Fla. -- With 8 days to go until the grand jury gets the case, today FBI agents spent the day combing the neighborhood of Sanford, questioning potential witnesses.
Federal officials call it a "parallel investigation," focusing on whether Trayvon Martin's civil rights were violated.
George Zimmerman says he shot the 17-year-old in self defense. A scream that lasts just a second is now the centerpiece of what happened 36 days ago in Sanford.
9-1-1 Operator: Do you think he's yelling HELP?
9-1-1 Operator: Alright, what is your ... (unintelligible)
Witnesses of this struggle have different versions of how they saw it happen. But forensic "audio" experts say their technology reveals it is "not" George Zimmerman screaming.
The experts who analyzed the calls for the Orlando Sentinel say their technology is wrong- only one percent of the time. It's the same kind used by our nation's top security entities.
But what is more certain than the technology -- the cries for what some say is justice in this case -- an arrest of Zimmerman won't be silenced easily.
That's the debate across the country right now.