Every development in the Trayvon Martin case continues to generate widespread reaction, both heated and polarized. George Zimmerman claims he shot Martin in self-defense, and Sanford, Florida’s investigating officers gave Zimmerman the benefit of the doubt. One key piece of evidence is a scream for help recorded during a 911 call. Was that Zimmerman or Martin who cried out before the shot was fired? The Orlando Sentinel submitted the recording to a forensic voice consultant. Jeff Weiner reports for the Sentinel.