close call. >> the defense's day was built around testimony from zimmerman's friends and colleagues, who all say it's his voice screaming for help in the background of the 911 call. >> do you know who is voice that is in the background, screaming? >> yes, definitely. it's georgy. >> i thought it was george. >> and tell me why you think that? >> just the tone, the -- just the volume and the tone of what i was hearing. and it just sounded like george. >> i recognized his voice. i've heard him speak many times. i have no doubt in my mind that's his voice. >> whose voice is it? >> george zimmerman's voice. >> there's absolutely no doubt in my mind that it's george zimmerman. and i wish to god i did not have that ability to understand that. >> lisa, given the totality of that testimony, is that why you believe it was unnecessary to call trayvon martin's father to the stand at the end of the day? >> no, i think because the two