Tape shows Zimmerman re-enacting Martin shooting for police

A newly released videotape shows George Zimmerman re-enacting for investigators his version of events the night he shot and killed unarmed teenager Trayvon Martin.

The re-enactment, which was conducted at the scene one day after the Feb. 26 shooting, was among new evidence released by prosecutors in advance of Zimmerman's trial for second-degree murder. Zimmerman, a neighborhood watch volunteer, says he killed Martin in self-defense.

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The full tape was made available on the GZlegalcase.com website managed by Zimmerman's defense team.

In the tape, Zimmerman states that he was attacked by Martin that night in a gated community in Sanford, Fla.

"He took my head and slammed it against the concrete several times, and each time I thought my head was going to explode and I thought I was going to lose consciousness," George Zimmerman tells police on the tape.

He says he "started screaming for help," but that Martin pressed his hands over Zimmerman's mouth and nose and told him to shut up.

"I didn't want him to keep slamming my head on the concrete so I kind of shifted. But when I shifted my jacket came up … and it exposed my firearm. That's when he said you are going to die tonight. He took one hand off my mouth, and slid it down my chest. I took my gun aimed it at him and fired."

Update at 3:35 p.m. ET: USA TODAY's Marisol Bello has more details from the video. Here's some of her initial report:

Wearing a white polo shirt and khaki slacks, Zimmerman said he first saw Martin in front of a house that had been broken into a few weeks ago. He said it was raining and Martin stopped in front of the house, looking around.

"I felt something was off about him," he said.

Zimmerman told police he drove past Martin and stopped a few houses up to call 911. He said he lost sight of Martin, who reappeared and circled his car with his hand on his waist band. He said the dispatcher asked him where Martin was. He said he didn't know so he drove in the direction where he saw Martin heading. Zimmerman told police the operator asked him where he was so they could send a police officer.

He didn't know the name of the street so he said on the videotape that he thought to get out and look for the street sign. At that point in the video, he got out of the police car to show officers how he walked on a concrete path behind the houses. Two bandages could be seen on the back of his head.

He said he didn't see Martin as he walked to the end of the path. At that point the operator told him not to follow Martin. Zimmerman said he was heading back to his car to meet the police and had gotten off the phone with 911 when he saw Martin through the darkness.

"Yo, you got a problem?" Martin yelled, according to Zimmerman. Martin walked toward him.

"No, I don't have a problem," Zimmerman said he responded.

"You got a problem now," Martin said, Zimmerman recounted. "And then he was here and he punched me in the face."

Zimmerman stood on the grassy patch showing police where he said he stumbled and fell on his back. He said Martin landed on top of him. The two struggled; Zimmerman says he never hit Martin, but tried to push him away. Martin, he says, grabbed his head and slammed it against the concrete.

"I kept yelling, 'Help. Help,' " he told police. He said Martin put one hand over his nose and the other over his mouth and yelled for him to "shut the (expletive) up."

He squirmed to break free because every time his head hit the pavement, he said, "it felt my head as if my head was about to explode."

He said a resident opened a back door during the commotion and Zimmerman called for help. The person said he called police.

"I said, 'No. Help me, I need help,' " Zimmerman said. No one came.

Zimmerman's shirt and jacket pushed up during the commotion, exposing the Kel-Tec 9mm handgun on his right hip. Martin looked at it and Zimmerman said he told him, "You re going to die tonight, (expletive)."

Martin took one hand off Zimmerman's mouth and brushed it down Zimmerman's side, going for the weapon, Zimmerman said.

But Zimmerman said he reached for it first.

"I grabbed my firearm and just shot him, one time," he said, making a gun with his hand and shooting motion. Martin sat up and said, "Oh. You got me. You got it. Something like that," Zimmerman said.

Zimmerman said he didn't think he had shot him and that Martin was saying he had given up.

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