As the Trayvon Martin controversy splinters into a debate about self-defense, a central question remains: Who was heard crying for help on a 911 call in the moments before the teen was shot?
A leading expert in the field of forensic voice identification sought to answer that question by analyzing the recordings for the Orlando Sentinel.
Tom Owen, forensic consultant for Owen Forensic Services LLC and chair emeritus for the American Board of Recorded Evidence, used voice identification software to rule out Zimmerman. Another expert contacted by the Sentinel, utilizing different techniques, came to the same conclusion.
Zimmerman claims self-defense in the shooting and told police he was the one screaming for help. But these experts say the evidence tells a different story.
On a rainy night in late February, a woman called 911 to report someone crying out for help in her gated Sanford community, Retreat at Twin Lakes.
Though several of her neighbors eventually called authorities, she phoned early enough for dispatchers to hear the panicked cries and the gunshot that took Trayvon Martin's life.
George Zimmerman, a Neighborhood Watch volunteer, shot Trayvon, an unarmed 17-year-old, during a one-on-one confrontation Feb. 26.
Before the shot, one of them can be heard screaming for help.
Owen, a court-qualified expert witness and former chief engineer for the New York Public Library's Rodgers and Hammerstein Archives of Recorded Sound, is an authority on biometric voice analysis — a computerized process comparing attributes of voices to determine whether they match.
After the Sentinel contacted Owen, he used software called Easy Voice Biometrics to compare Zimmerman's voice to the 911 call screams.
"I took all of the screams and put those together, and cut out everything else," Owen says.
The software compared that audio to Zimmerman's voice. It returned a 48 percent match. Owen said to reach a positive match with audio of this quality, he'd expect higher than 90 percent.
"As a result of that, you can say with reasonable scientific certainty that it's not Zimmerman," Owen says, stressing that he cannot confirm the voice as Trayvon's, because he didn't have a sample of the teen's voice to compare.
Forensic voice identification is not a new or novel concept; in fact, a recent U.S. Department of Justice committee report notes that federal interest in the technology "has a history of nearly 70 years."
In the post 9-11 world, Owen says, voice identification is "the main biometric tool" used to track international criminals, as well as terrorists.
"These people don't leave fingerprints, but they do still need to talk to one another," he says.
'The home run'
Trayvon Martin shooting: It's not George Zimmerman crying for help on 911 recording, 2 experts say
Trayvon Martin's family says unarmed teen begged for his life. Experts say it's not George Zimmerman's voice.
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