SANFORD, Fla. April 20, 2012— -- George Zimmerman stunned a Florida court today by taking the stand and apologizing to the parents of Trayvon Martin, who were sitting in the courtroom during Zimmerman's bond hearing.

"I am sorry for the loss of your son. I did not know how old he was. I thought he was a little bit younger than I am. I did not know if he was armed or not," Zimmerman said addressing Martin's family directly.

Martin's father, Tracy Martin, cried tears of anger after the apology, his attorney Ben Crump told reporters after the hearing.

Zimmerman took the stand wearing a dark suit with his hands shackled to a belt around his waist. He appeared to be wearing a bullet-proof vest beneath his loose-fitting suit.

His surprising testimony came the same day that ABC News exclusively obtained a photograph showing the bloodied back of Zimmerman's head, which was apparently taken three minutes after he shot and killed Martin. The photo could give credence to Zimmerman's claim that Martin had bashed his head against the concrete as Zimmerman fought for his life.

Click here to view the image. Warning: graphic content.

The bond hearing concluded this morning with Judge Kenneth Lester agreeing to allow Zimmerman, who is charged with second degree murder, to post a $150,000 bond to get out of jail. The prosecution had argued that Zimmerman should be denied bail or that it should be set at $1 million.

Zimmerman's attorney, Mark O'Mara, told reporters after the hearing that he does not expect Zimmerman to be out of jail for a couple of days because it will take some time to come up with the money for bail.

After the court hearing, O'Mara rejected the suggestion that they were "pandering" to the parents, and said Zimmerman wanted to apologize after hearing the parents on TV said that he had never done so.

"He wanted to respond. I took it that the family wanted to hear from him and he wanted to say it… It should have been done in a private setting but that wasn't afforded him," O'Mara said.

Ben Crump, a lawyer for Martin's parents, said the family was furious that Zimmerman could "give this self serving apology so he could get a bond." One of the lawyers for the family called the apology "disingenuous and insincere."

Zimmerman, 28, is being held on charges of second-degree murder for the Feb. 26 shooting of Martin, 17, which could carry a life sentence if he is convicted.

The exclusive photo obtained by ABC News shows blood trickling down the back of Zimmerman's head from two cuts. It also shows a possible contusion forming on the crown of his head. The original police report that night notes that the back of Zimmerman's head was wet, and that he was bleeding from the nose and head.

Zimmerman told police that night that he shot and killed the teenager in self-defense after Martin punched him and pounced on him. Zimmerman told police that Martin then bashed his head into the concrete sidewalk during the altercation that took place in the tidy middle-class development of the Retreat at Twin Lakes in Sanford, Fla.

Zimmerman was treated at the scene by paramedics, then cuffed and driven in a police cruiser to the Sanford police station. He was questioned for hours and later released. In police surveillance video obtained last month by ABC News, Zimmerman's wounds are not apparent, and there were no bandages on his head.

Zimmerman was not admitted to a hospital or given stitches the night of the incident.

The person who took the photograph of a bloodied Zimmerman, asking not to be identified, told ABC News exclusively that they did not see the scuffle that night, but did hear it. The person recalled seeing Martin's prostrate body on the wet grass and said the gunpowder burns on Martin's gray hoodie were clearly visible.

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