George Zimmerman Trial for Trayvon Martin Death: Prosecution Paints Defendant as Vigilante Now, to the explosive start of george zimmerman's high-profile trial. As a prosecutor used zimmermann's own words to portray him as a vigilante who targeted martin. Let's go to matt gutman in sanford, florida. He has the latest for us. Prosecutors expected to roll out key witnesses today who are going to paint george zimmerman as a man almost destined to kill trayvon martin. A man who wanted him dead. The defense is going to counterpunch, saying zimmerman acted as many of us would act in self-defense. After a day in court where lawyers dropped f-bombs, and their jokes bombed, shocking jurors. It took a few words to send a jolt through the courtroom. punks. These , they always get away. Those were the words in that grown man's mouth, as he followed in the dark, a 17-year-old boy who he didn't know. Reporter: Assistant district attorney john guy opening the prosecution's case by quoting what george zimmerman told the police dispatcher the night he shot and killed trayvon martin. Those were the words in that defendant's head, just moments before he pressed that pistol into trayvon martin's chest and pulled the trigger. Reporter: Prosecutors saying zimmerman was hell-bent on harming martin. George zimmerman did shoot trayvon martin because he had to. Reporter: Then came the defense's attorney. Attorney don west, instead opting to open with a joke. Knock, knock? Reporter: Not a single juror laughed. And look closel that's the lead prosecutor, shaking his head. West's statement lasted 2 1/2 hours, five-times as long as the prosecutor's. But the all-female panel sat up as he argued zimmerman was attacked by martin and fired only in self-defense. George zimmerman was crying out for help. And no one helped. Yes, he did have the gun. And thank god. Reporter: Already, four witnesses taking the stand, including the police dispatcher, who spoke to zimmerman that night. Are you following him? We don't need you to do that. Reporter: Saying zimmerman didn't follow his instructions. But he didn't think that then-28-year-old neighborhood watch volunteer sounded hostile during their call. Did you hear any of that hostility in the conversation? Reporter: I was there in court, robin, as trayvon martin's mother rushed out, overcome by emotion. Trayvon martin's father, dabbing away the tears. We could see over 200 witnesses in this trial. Those wounds for this family opening up again and again as this trial continues. We're going to bring in abc news chief legal affairs anchor, dan abrams, right now. Break down the opening arguments, beginning with the prosecution. I think the prosecution was very effective by starting what is in george zimmman's head? For second-degree murder they have to show intent. They are talking about the words he was saying. What was he saying on the 911 tape to create a whole atmosphere surrounding george zimmerman, that was about aggression and was all part of him going after trayvon martin. I think it was very effective. The defense, on the other hand, they, at this point, have a pretty strong legal defense. For him to start with this knock-knock joke. And put aside the fact that it's almost absurd, the notion in this case, of starting the defense with a knock-knock joke. But the joke itself was also offensive to the jurors. It was basically saying, how dumb are jurors, who might be picked to be on the george zimmerman case? Oh, they know nothing about george zimmerman. Ha, ha. It's not only not funny, but insulting to them. The other thing I think was a problem in the context of the defense's opening, was at one point, you heard the defense attorney talk about the shooting. And he says, thank god that george zimmerman had a gun, meaning so he could defend himself. There's a way for you to present this case and say, he was right, he was entitled. He shouldn't be prosecuted. But to say, thank god, I think there were two, main points with that joke and those words that could stick with these jurors in a very, very dangerous way for the defense. And quickly, today, prosecutors are going to try to convince the judge to allow nonemergency calls that zimmerman made to be played in court. They want to show a pattern. This is a guy that called 911 all the time. He was always angry. He was always thinking that there was someone out there. And they think that that's relevant to his state of mind. We'll see today if the judge allows that in. Dan, thank you very much. Let's go to josh elliott and