Today in a courtroom in Florida, a spectacle. Three hours of can't look away testimony from the man accused of murdering an apparently unarmed teenager over loud rap music in a car. Michael Dunn... See More
Today in a courtroom in Florida, a spectacle. Three hours of can't look away testimony from the man accused of murdering an apparently unarmed teenager over loud rap music in a car. Michael Dunn repeatedly tried to convince the jury he acted in self-defense while prosecutors repeatedly ripped into him as a cold blooded killer. This is a case that touches the two classic American hot buttons of race and guns. And NBC's Ryan Owen has this report for our series "Crime and punishment." I'm looking out the window and I said you're not going to kill me you son of a And I shot. Reporter: In his own words and in riveting detail -- It wasn't just my life I was worried about, you know? Reporter: Admitted killer Michael Dunn recreates for the jury moments that led to the shooting death of 17-year-old Jordan Davis. Did you notice any differences about your body physically? I'm shaking. I'm quivering like a leaf. Reporter: Prosecutors call it cold blooded murder. Dunn maintains it was self-defense. It started when Dunn and his fiancee Rhonda rower pulled into a Jacksonville, Florida, gas station in November 2012. They parked in ex-to an SUV full of teens. Body panels on the SUV were rattling. My rear-view mirror was shaking. My eardrums were vibrating. This was ridiculously loud music. Dunn's fiance testified the 47-year-old software developer had this reaction? And what did the defendant say? I hate that thug music. Reporter: Rower went inside to buy a bottle of wine. Seconds later, gunshots. Oh, my god. Somebody is shooting. Reporter: Dunn pulled his semiautomatic pistol out of the glove box and fired ten times. Today he testified while she was in the store he talked to the young men in the SUV and said can you turn that down, please. They turned it off. If the music wasn't off, at least the base stopped completely. Okay. And at that point, what did you say? I said thank you. Reporter: Dunn said the pleasantries didn't last long. He said the 17-year-old in the rear passenger seat started mouthing off. I should Kill that . Now he's screaming. There's no mistake of what he said. That is what he said. Reporter: Today, Dunn tried to convince the jury Jordan Davis was a foul moout mouuthed shotgun wielding teen who actually pointed a gun to him. To my eye it was a 12 gauge, maybe 20. He said yeah, I'm going to kill you. I'm looking at a barrel. He's showing me a gun and he's threatening me. Anticipa and after he opened the door, he looked at me and said you're dead . At this point, what did you believe was about to happen to you? I thought I was going to be killed. Reporter: That was only one of the buzz words Dunn used to try to convince this jury the shooting was self-defense. He seemed to hit them all. I was still fighting for my life. I knew I had done nothing wrong. I had every right of self-defense and I took it. Reporter: But prosecutor John guy would have none of it. Jordan Davis was never a threat to you, was he, Mr. Dunn? Absolutely he was. Reporter: As soon as his cross-examination began, we reminded why defense attorneys cringe when their clients take the stand. I don't want to call it an act of desperation, but they really had no choice. Without his testimony, there was no evidence of self-defense. All you had was a man shooting nine times into a car with a bunch of teenagers. He would easily be convicted. So he had to get on the stand. He had to explain why he fled the scene and why he didn't call 911. You were being disrespected by a mouthy teenager, weren't you? No, I was being threatened. Threatening to kill somebody isn't a disrespect. That is just crazy. Reporter: Prosecutor guy reminded the jury no gun was found in the teens' SUV and grilled Dunn on every inconsistency. Including the fact that his own fiancee said he never mentioned a gun the night this happened. You did not tell her in that three miles anyone pulled any weapon on you, did you? I think I did. I think I was very clear that they threatened my life. Reporter: My question was did you tell her they had a weapon of any kind? Yes, I did. Reporter: Mr. Dunn, the truth is you never told the love of your life that those boys had a gun. You weren't there. Reporter: All right, ma'am, if you come right around here. Later, prosecutors brought his fiancee back to the stand to hammer home the point. Did the defendant ever tell you he saw a gun in that red SUV? No. Back in the hotel room that same night, did the defendant ever tell you he saw the boys with a firearm? No. Did he ever tell you he saw the boys with a weapon? No. Reporter: Dunn claims the fiance got something else wrong, the last words she heard him say before the shooting. I hate that thug music. Reporter: You don't recall saying I hate that thug muse snik. No, if I Staal called it anything, I would call it rap crap. Thug music isn't something I say. Reporter: He was quizzed about his behavior after the shooting. Mr. Dunn, you left the gas station because you knew you had shot into the car of an four unarmed teenagers. Reporter: Dunn acknowledged that he and rower fled the scene of the shooting and never called police. Instead, they returned to this hotel and ordered pizza and made some cocktails. I didn't call the police until the following morning. Reporter: You called the pizza man. Reporter: Dunn said he didn't realize anyone can be killed until late that night when he used his cell phone to look up information about the shooting. I ran to the bathroom and vomited. Reporter: But he still didn't call police. He drove home to central Florida where he was later arrested. Dunn was on the stand for more than three hours and he was the defense's final witness. All right, ladies and gentlemen, the defense has now rested their case. Reporter: By late tomorrow, the jury should begin deliberating his fate. Prosecutors want first degree murder, but many observers think that's a stretch. They've lost credibility by doing that. This is not a case of premeditated murder. He didn't know these kids ahead of time. He didn't go to the gas station in order to shoot them. They love to overcharge because it frightens defendants. It hurts them in trying to get out on bail. It sends the message to the public that this is really a vicious crime, but when they get to the trial, can they really prove it? Reporter: That will be up to 12 jurors who will have Michael dup Dunn's own words fresh in his mind. Reporter: I'm Ryan Owens for "Nightline" in Jacksonville, Florida.
This transcript has been automatically generated and may not be 100% accurate.