George Zimmerman, the neighborhood watch crime captain who shot dead 17-year-old Trayvon Martin, originally told police in a written statement that Martin knocked him down with a punch to the nose, repeatedly slammed his head on the ground and tried to take his gun, a police source told ABC News. Zimmerman had claimed he had called police about Martin, whom he found suspicious, then went back to his car when Martin attacked him, punching him. The new information is the most complete version yet of what Zimmerman claims happened on the night of Feb. 26 when he shot and killed...