SANFORD, Fla. June 29, 2012— -- George Zimmerman's father listened to frantic howls for help overheard in a 911 call today and told a Florida courtroom that the voice "was absolutely George's."
Zimmerman's father, Robert Zimmerman, took the stand during a bail hearing for his son. Zimmerman is charged with second degree murder in the shooting death of unarmed teenager Trayvon Martin.
Both the father and the son appeared in court with the distinct outline of bullet proof vests beneath their suits.
The judge did not immediately rule on Zimmerman's request to be let out on bond.
During the hearing, Zimmerman's lawyer Mark O'Mara played a tape of a 911 call in which a woman tells police that someone is yelling and she thinks they are calling for help. In the background of the call can be heard frantic screams for help, at least 14 calls for help in a 40 second period.
The howls stop and the woman tells the 911 dispatcher that she just heard a shot.
Robert Zimmerman listened to the tape with the rest of the courtroom and was then asked if he could identify the voice calling for help.
"It was definitely George's," the father said.
The parents of Trayvon Martin insist that the voice calling for help that their son.
Earlier in the hearing, a member of a Sanford, Fla., ambulance crew told a court that Zimmerman's head, including his moustache and beard, were covered in blood after the shooting of Martin.
EMT Kevin O'Rourke testified during Zimmerman's bond hearing this morning that "45 percent" of Zimmerman's head had blood on it and that the lacerations on Zimmerman's head "would probably need stitches."
O'Rourke also testified that Zimmerman's nose was broken and urged him to see a doctor within 24 hours.
The EMT examined Zimmerman after having checked on Martin, who had died after being shot by Zimmerman.
Zimmerman, 28, has said that he shot the unarmed teenager after being knocked down, having his head banged on the pavement and then believing that Martin was going for Zimmerman's handgun.
Zimmerman's lawyers today tried to establish that their client might have thought he had suffered a "life-threatening injury."
In addition, a forensic accountant for the defense, Adam Magill, walked the court through the donations to Zimmerman's legal defense fund.
Under cross examination, however, accountant Adam Magill testified that Zimmerman and his wife had shifted about $132,000 between four accounts, often transferring sums of $9,999. Transfers of $10,000 or more are required to be noted by banks and a prosecutor suggested it was intended "to make it look like he didn't have the money."
Zimmerman hopes a judge will agree to let him out of jail today. The judge revoked Zimmerman's $150,000 bond earlier this month when prosecutors told the judge Zimmerman and his wife misled the court about how much money they had.
He appeared in court today without the shackles he wore in his last appearance, but the outlines of a bullet proof vest under his gray suit was clearly visible. He faces the prospect of a prolonged stay in jail if his plea to get out on bond is rejected.
Also present was the family of Trayvon Martin.
It is Zimmerman's second appearance before Circuit Court Judge Kenneth Lester . During the last one on April 20 he sat stone faced as his wife brazenly lied to the court about the Zimmerman's finances.
Zimmerman's wife, Shellie Zimmerman, told the judge she was essentially broke, when in the days leading up to that hearing, she and her husband held clumsily coded jailhouse conversations about shuffling to various accounts $135,000 in cash amassed from donations to Zimmermans website. Audio tapes of the hushed jailhouse conversations were released earlier this month.
Shellie Zimmerman has been charged with perjury.
Orlando defense attorney Mark Lippman said that whether or not Lester grants Zimmerman bail, he is likely to "receive a tongue-lashing from the judge."
It is also expected that if the normally stern judge grants Zimmerman bail, the bond would be much higher than his previous bond of $150,000. Typically bail bondsmen charge 10 percent of the total bond.
ABC News' Candace Smith contributed to this report