"I tried to defend myself," Zimmerman said in his first interview the night of the shooting. "He just started punching me in the face, and I started screaming for help. I couldn't see. I couldn't breathe."
Zimmerman also said Martin noticed he was armed with a gun and tried to reach for it.
"I felt his arm going down my side, and I grabbed it. I grabbed my firearm, and I shot him one time," Zimmerman told police.
6. Martin and Zimmerman's mothers testify: The mothers of Zimmerman and Martin both claimed screams for help on a 911 call placed the night Martin died are those of their son.
Identifying the voice is considered key to proving whether Zimmerman or Martin was the aggressor the night the 17-year-old was shot and killed.
On Friday, prosecutor Bernie de la Rionda played the 911 call for Sybrina Fulton, Martin's mother. When de la Rionda asked Fulton if she recognized the screaming voice, Fulton said it belonged to "Trayvon Benjamin Martin." During cross-examination, defense attorney O'Mara asked Fulton, "As his mother, there was no doubt it was him screaming?" She told him, "Absolutely."
Hours later, the defense called Gladys Zimmerman as its first witness. O'Mara played the 911 call and asked her if she could tell whose voice is on the recording. She confirmed it was her voice of her son, George.
When asked by O'Mara how Zimmerman could be certain, she replied, "I know because he's my son."
O'Mara said at a press conference after the day's testimony that both mothers may indeed hear their own son's voice on the 911 call.
"We have to treat them as the grieving parents they are in different ways," he said.