Trayvon Martin's Father Recalls 'Listening to His Life Being Taken'

SANFORD, Fla., July 8, 2013— -- Trayvon Martin's father took the stand today and challenged the testimony of two police officers who had testified that he said it was not his son screaming for help on 911 tapes.

The identity of the voice howling for help moments before George Zimmerman, shot and killed Martin was the focus of the defense's first full day of testimony.

While the prosecution insists that the voice pleading for help is Trayvon Martin, the defense has produced witnesses identifying the voice as Zimmerman's.

Zimmerman, 29, is charged with second degree murder for shooting Martin, 17, on Feb. 26, 2013. Prosecutors say the former neighborhood watch captain was profiling and following Martin. Zimmerman maintains that he shot the teenager in self-defense.

Two police officers described today how Tracy Martin, the slain teenager's father, listened to the tapes of the 911 calls two days after his son was killed. The screams for help could be heard in the background.

Catch up on all the details from the George Zimmerman murder trial.

The father said , however, that he did not deny it was his son's voice.

"[I] shook my head and said I can't tell," Tracy Martin told the Florida court. "I never said that no, it was not my son's voice."

Under cross examination by the prosecution, Tracy Martin said listening to the tape was an awful moment for him and that his "world turned upside down that day." The six women jurors watched the father intently during his testimony.

Tracy Martin later concluded that it was his son, he said, after listening to the tape about 20 times.

"I was listening to my son's last cry for help. I was listening to his life being taken. I was coming to grips with Trayvon was here no more. It was tough," he said.

Trayvon Martin's mother, Sybrina Fulton, and older brother, Jahvaris Fulton, have also testified that it was Trayvon pleading for help.

However, former Sanford police chief Bill Lee, speaking for the first time on the case since he was dismissed from his job, said that when the entire Martin family listened to the tapes it was in the mayor's office and Lee was excluded from the room.

Before the father took the stand, the jury heard two Sanford, Fla., police officers say that Tracy Martin said it was not his son's voice.

"I believe my words were, 'Is that your son's voice in the background?'" said investigator Chris Serino.

"What was his response?" asked Zimmerman's lawyer Mark O'Mara.

"It was more of a verbal and non-verbal. He looked away and under his breath said, 'No,'" responded Serino.

Serino, the lead investigator in Martin's death, said he played the tapes for Tracy Martin two days after his son's death on Feb. 26, 2012. He said the father was desperate for answers about his son's death.

The investigator said he played five or six of the 911 calls for Tracy Martin in which the screams for help could be heard in the background.

Officer Doris Singleton said she was choked up as she watched the tapes being played for the dad, who was listening to the screams and the gunshot for the first time.

"I could feel for him because I have children," said Singleton. "I could see him wiping tears from his eyes…You could see that he was upset."

She, too, said that Tracy Martin said he did not believe the screams were made by his son.

Serino later said when cross examined by the prosecution that Zimmerman also said "that doesn't even sound like me" when asked about the screams.

Their testimony came after five of Zimmerman's friends and co-workers took the stand today and said it was Zimmerman's voice screaming for help seconds before he shot the teenager.

The George Zimmerman Case in Pictures

"It's Georgie," said family friend Sandra Osterman when asked about the screams. "I know it."

John Donnelly, who called Zimmerman a "dear friend," told the jury, "There is no doubt in my mind. That is George Zimmerman and I wish to God I did not have the ability to make the determination," he said, wiping his eyes.

Donnelly, a former Army medic during the Vietnam war, reinforced his opinion under cross examination.

"The voice screaming in that video is absolutely George Zimmerman, sir," he testified.

He rejected the suggestion that he would color his testimony to help his friend.

"This courtroom is about truth," Donnelly said.