end of this trial you will know in your head, in your heart, in your stomach that george zimmerman did not shoot trayvon martin because he had to. he shot him for the worst of all reasons, because he wanted to. >> george zimmerman is not guilty of murder. he shot trayvon martin in self-defense after being viciously attacked. >> in his closing arguments mark o'mara called for a moment of silence, first for a minute and then two and then more. to demonstrate how much time the defense says martin had to run and get home after he saw zimmerman. >> that's how long trayvon martin had to run, about four minutes. when he said he was running, that's how long. >> then hauled out a chunk of concrete to show how martin used the sidewalk as a weapon.