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George Zimmerman trial: Person screaming on 911 call is "my son, George," murder suspect's mother testifies

George Zimmerman sits in court during his trial in Seminole circuit court, July 5, 2013 in Sanford, Florida. (Photo by Gary W. Green-Pool/Getty Images)

(CBS) --The mother and uncle of accused murderer George Zimmerman testified late Friday afternoon that they recognized his voice as the person screaming in the background of a crucial 911 call.

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READ: Trayvon Martin Shooting: A timeline of events

The contested call was placed by a neighbor the night Zimmerman fatally shot Florida teen Trayvon Martin during an altercation in a Sanford, Fla., gated community last year. Friday morning, Martin's mother, Sybrina Fulton, testified the screams were those of her son.

The testimony of Zimmerman's family members came after the state formally rested its case around 5 p.m. Zimmerman is accused of second-degree murder in Martin's shooting death. He claims he shot the teen in self-defense.

The 911 call is a key piece of evidence because it could provide clues as to who was the aggressor in the fatal Feb. 26, 2012 confrontation.

The first witness to testify for the defense was Gladys Zimmerman, the defendant's mother. When asked who she thought was screaming in the background of the call, she said, "My son, George," motioning to him sitting in the courtroom.

When asked whether she was certain, she nodded, saying, "Because he's my son."

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She said she had heard her son scream, but not in the way he was screaming on the call, demonstrating "anguish," "fear," and "terror," she said.

Gladys Zimmerman's brief testimony was followed by Jorge Meza, Zimmerman's uncle.

Meza, employed by the Orange County Sheriff's Office, said he's known Zimmerman since "Oct. 5, 1983. The day he was born."

Meza described working on the computer one evening last year when he heard his nephew's voice broadcast on a television news report his wife had been watching.

"It is the unique way you recognize your family member when they laugh, when they cry," Meza said. "This was the moment I recognized it was George screaming for help."

Meza said he instantly recognized the voice, though he hadn't been watching the news report with his wife and said she didn't tell him the report was about his nephew.

"That voice just came and hit me," Meza said. "It hit me the way I heard that, but more than heard that, I felt it inside of my heart. I said, 'That's George.'"

Court has recessed for the weekend, and the defense is expected to continue its case beginning Monday at 9 a.m.

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