The George Zimmerman trial continues this week with more witness testimony, including that of an FBI Audio Expert.

Today the trial continued with an expert testimony about the 9-1-1 call recordings, in which cries for help can be heard, from Hirotaka Nakasone, who testified that there was no way of telling who the voice heard yelling for help belonged too.

“It’s not fit for the purpose of voice comparison,” Nakasone testified.

The jury also heard testimony from Officer Doris Singleton, who took Zimmerman’s statement after the shooting. ABC.com is currently streaming the trial live on the web, you can watch it here. Zimmerman could face life in prison if found guilty.

Zimmerman, a former member of the neighborhood watch on trial for second-degree murder, is accused of shooting, and killing, Trayvon Martin, an unarmed seventeen-year-old. The case received huge media attention when it was discovered that Martin, a young African American, was shot and killed in a gated community after being followed by Zimmerman for wearing a suspicious hoodie. Zimmerman is pleading not guilty for reasons of self-defense, while many have claimed that Martin’s death was a simple case of racial profiling.

The high-profile trial, which began last week, has already been home to many dramatic testimonies. The testimony of Rachel Jeantel, a girl who claims she was the last person to speak to Martin before his death, caused a bit of a publicity uproar when she was subjected to a five hour cross examination by defense attorney, Don West. West badgered Jeantel, and called her credibility into question when she failed to read a letter she had allegedly written with the help of a friend to Martin’s mother on the stand. West proceeded to accuse her of lying under oath, according to The Washington Times. West has been a subject of controversy since day one of the trial, when he began his opening statement with a ‘knock knock’ joke.

Witnesses, John Good and Jonathan Manalo, two neighbors who lived near the crime scene, also testified, commenting on the physical confrontation between Martin and Zimmerman, and Zimmerman’s immediate reaction to Martin’s death, according to ABC News. Good testified that, while he did not get a clear look at the altercation, he did see what he believes to have been Martin straddling Zimmerman, a fact that could help Zimmerman’s defense, who claims that Martin was punching Zimmerman and banging his head into the concrete sidewalk. Other witnesses included first responders and other neighbors. The jury also heard various 9-11 calls from the incident and was shown crime scene photos, according to CBS News.

–Olivia Truffaut-Wong