Days have elapsed since February 26, the fateful night when 17-year-old Florida boy Trayvon Martin was shot dead by neighborhood watch volunteer George Zimmerman.

A video showing a handcuffed Zimmerman emerging from a police car to an interrogation room seem to refute his contention that Martin attacked him and banged his head on the concrete sidewalk. No signs of such injuries appeared.

In the meantime, two experts now say that the voice analysis of 911 emergency calls made in the last few seconds of Martin's life indicates that it was likely a teenager and not Zimmerman screaming, "Help!"

Tom Owen, forensic consultant for Owen Forensic Services LLC and chair emeritus for the American Board of Recorded Evidence, used voice identification software called Easy Voice Biometrics to rule out Zimmerman as the screamer.

The software upshot showed a 48 percent match which is far less than the 90 percent positive match expected with audio of that quality.

Owen concluded with "reasonable scientific assurance that it is not Zimmerman's voice," but could not confirm that it was Martin's cry because he had no sample of the teen's voice to compare.

A second expert, Ed Primeau, a Michigan-based audio engineer and forensics expert, used audio enhancement and human analysis rooted in forensic experience to arrive at the same conclusion. He said that he believes that it is Trayvon Martin's voice in the background, "without a doubt."

Zimmerman's family disagrees with the experts claims.

Robert - Zimmerman's brother - told a Miami television station that he believed it was his brother who called for help.

"I know that's George. I know that one of the saddest things for him in this whole thing is that no one came to his aid despite those screams," he said.

He believed that was George did to defend his life could have been avoided.

The unarmed Trayvon Martin was shot in Sanford, Florida and the issue of his age and race have pushed this tragic story into the forefront of media.

Martin was an African American teen. He was killed by George Zimmerman, a 28-year-old man of mixed family heritage - a Latin American mother and a white American father.

Martin was walking from a 7-Eleven convenience store to the home of his father's fiancé. That was when Zimmerman, a community watch volunteer, began following Martin. He called the Sanford Police Department saying he witnessed suspicious behavior.

Shortly afterward, there was a confrontation that ended when Zimmerman fatally shot Martin.