New evidence was released Wednesday in the Case Against George Zimmerman.
Special Prosecutor Angela Corey released two voice samples Zimmerman gave to authorities.
In them, he can be heard repeatedly shouting "Help" and "Help me."
The samples were taken so FBI audio experts could try to determine whether the voice heard screaming for help in the background of a 911 call belonged to Zimmerman or 17-year-old Trayvon Martin, on the night the teen was killed.
Zimmerman gave that voice sample to Tom Artingstall, an investigator with the Seminole/Brevard County State Attorney's Office. This test was done on March 22, which was the same day Corey's office took over the case.
For the test, Artingstall tried to mimic the conditions that would most closely resemble the 911 call from the night Martin was shot. Artingstall phoned into the Seminole County 911 dispatch line and then had Zimmerman yell while being some distance away from the phone.
Several media organizations hired independent audio experts to see if they could match Zimmerman's voice to the voice heard screaming for help on the 911 tape. They concluded the voice on the 911 tape likely did not belong to Zimmerman.
However, the FBI experts who did the voice comparison issued a 3-page report on their findings and indicated, "Voice comparison is not possible for the designated voices due to extreme stress and unsuitable audio quality."
On March 15, Benjamin Crump, the attorney for Martin's family, said the family is convinced those calls for help on the 911 tape were from Trayvon.
"To hear his pleas, to hear where three witnesses have said the young man was crying out for help before George Zimmerman shot him in cold blood," Crump said during a press conference.
Zimmerman doesn't want to wear prison uniform in court
Meanwhile, Zimmerman wants to wear plain clothes to his bond hearing Friday.
In a new motion filed Monday, defense attorney Mark O'Mara asked the judge to allow his client to wear civilian clothing instead of a prison uniform.
- VIEW: Motion to permit the defendant to appear in civilian clothing and without restraints at bond hearing
Zimmerman is charged with second-degree murder for shooting and killing Martin on Feb. 26.
O'Mara also asked that Zimmerman be allowed to appear without handcuffs or restraints. He noted his client was allowed to wear plain clothes to his first bond hearing in April.
Zimmerman's initial bond was revoked after it was revealed that his wife, Shellie, lied in court about how much money the couple had. He surrendered himself again to the Seminole County Jail in early June.
"It is unlikely that the interest by the media in this case will wane any time soon," said O'Mara in his latest motion. "The manner in which Mr. Zimmerman is portrayed by the media will have a tremendous impact on his ability to receive a fair trial."
O'Mara claimed the image of Zimmerman in a jail uniform and shackles at his first court appearance has circulated across the Internet, calling the photo "extremely prejudicial" to his client.