(CBSNews) -- The mother and brother of Trayvon Martin testified Friday morning that the Florida teen was the person who was screaming in the background of a 911 call the evening he was fatally shot.
Sybrina Fulton, Martin's mother, was the first to take the stand. She began by describing her son's tattoos, including Fulton's name, which she said was on his wrist. Prosecutor Bernie de la Rionda played her the tape of the 911 call the night of the fatal altercation with former neighborhood watch captain George Zimmerman.
"Ma'am that scream or yell, do you recognize that?" de la Rionda asked.
"Yes," she said.
When asked who she thought it was, she said, "Trayvon Benjamin Martin."
The 911 tape is a crucial piece of evidence because it could provide clues as to who was the aggressor in the Feb. 26, 2012 confrontation. Zimmerman, 29, claims Martin attacked him and he shot in self-defense.
Who is screaming on the tape has been a key point of contention. Before the trial launched last week, defense attorneys successfully blocked a prosecution expert who said he identified the screams as Trayvon Martin. Zimmerman's father has said the screaming was his son's.
Early this week, a voice expert testified that is was impossible to scientifically analyze whose voice was screaming, but that a person familiar with the voice--such as a family member - might have a "better chance" at identifying it.
"If it wasn't your son screaming, if it was in fact, George Zimmerman, you would have to accept the possibility that it was Trayvon Martin who caused his own death, correct?" defense attorney Mark O'Mara asked.
"Correct," Fulton said.
O'Mara asked her whether she would hope that her son did nothing that would cause his own death.
"What I hope for is this wouldn't have never happened, and he would still be here. That's my hope," Fulton said.
Also taking the stand Friday morning was Martin's brother, Jahvaris Fulton. Fulton said he was "very close" with his brother and that he recognized the voice on the tape as Martin's.
Responding to questions from O'Mara, however, Fulton said he told a reporter that he wasn't sure who the voice belonged to.
"I guess I didn't want to believe that it was him, that's why during that interview I said I wasn't sure," Fulton said. "Listening to it was clouded by shock and denial and sadness."