SANFORD, Fla. — The prosecution in the murder trial of George Zimmerman wrapped up its case after a dramatic day of testimony Friday, with Travyon Martin’s mother and brother saying the screams for help that can be heard in the background on a 911 call came from the 17-year-old.

Before the defense began its case, defense attorney Mark O’Mara argued Zimmerman should be acquitted, saying prosecutors hadn’t proved their case.

“What is before the court is an enormous amount of information my client acted in self-defense,” O’Mara told Judge Debra Nelson, who continued to listen to arguments late Friday afternoon.

Before the state rested, Martin’s mother, Sybrina Fulton, sat expressionless on the witness stand while prosecutors played the 911 recording, in which high-pitched wails can be heard as Zimmerman’s neighbor urges a dispatcher to send police quickly. Moments later on the call, there is a gunshot and the crying stops.

“Who do you recognize that to be?” prosecutor Bernie de la Rionda asked Fulton.

“Trayvon Benjamin Martin,” she replied.

She was followed on the stand by her son Jahvaris Fulton, Martin’s 23-year-old half brother, who also testified the cries came from Martin.

Identifying the voice could be critical to the case because it could help the jury determine who was the aggressor during the scuffle that ended with Zimmerman killing Martin. Zimmerman’s father has claimed it’s his son yelling.

Zimmerman, the former neighborhood watch volunteer charged with second-degree murder, has said he shot the teen in self-defense during a fight.

Late in the afternoon, the prosecution rested after calling 38 witnesses over two weeks.