Since Saturday when a jury announced it was deadlocked on a first degree murder charge against Florida software developer Michael -- The question so many of asked is what happened. Yes Dunn was... See More
Since Saturday when a jury announced it was deadlocked on a first degree murder charge against Florida software developer Michael -- The question so many of asked is what happened. Yes Dunn was convicted of three counts of attempted murder for firing at a car with -- inside after an argument over loud music. But on the most serious charge alleging the murder of seventeen year old Jordan Davis to jurors could not agree. Tonight in an ABC news exclusive. We know why. ABC's Byron Pitts has just finished the very first interview was one of those jurors for our series crime and. Do you think Michael -- -- -- with -- At this point. I I do myself personally yes. She was Jordan number four Valerie is her first -- home care nurse administrator she asked we not give her full name. For the first time tonight we're hearing what happened inside the deadlocked jury room where twelve people struggled to decide the fate of admitted killer Michael -- When you went to deliberating room you thought Michael Dunn was guilt. Of killing seventeen year old -- Yes what convinced you. Kinney it was unnecessary he didn't think Michael Dunn had to -- -- I don't believe. Most of the jury she told us agreed with her you -- first -- -- first pole guilt or innocence in the murder of Roger Davis what was the vote. Ten to 210 people thinking he was -- yes. And to set self defense 47 year old Michael Dunn never denied he shot -- killed seventeen year old Jordan Davis. But from the witness stand he pleaded it was self defense. Reenacting for the jurors those last fateful moment it's. And -- -- you're not gonna kill me is subject should -- shop. Sounds of gunshots were captured on the store surveillance -- And eventually pulled away. In town for a wedding he drove back to his hotel. And ordered pizza. Yeah. Yeah states is facing the -- to a car for unarmed teenagers since incorrect. During his testimony Dunn says he was sitting in this car waiting on his fiancee the gun inside the store. There were four teenagers and an SUV parked next to music player. He asked him to turn it down. Mind your job as a reminder notices. Ridiculously. Loud music which -- -- ask in the boy's attorney music -- Some of jurors said you know he even mentioned I've done in multiple times in my hometown asked folks to turn down their music and they get it. And that's what we saw little bit of the ego. Initially the music was turned down and then turned up again an argument started. -- -- seventeen year old Davis verbally threatened him that was about to get out of the SUV I hear. I should chill. -- and kill them. Now -- screening done insisted he saw what looked like a gun. Though police never recovered one in the vehicle or in the area and the teenagers who survived have always maintained there was no gun. And he says yeah until you -- American and let you know barrel. He's he's shown me -- he's threatening knee after the open -- the lower than you looked at me and said you're dead. At that point. What did you believe was about to happen to you. I think -- diners can be killed. Valerie says that was a key moment in the trial. -- insistence he believed he was in danger. That in this final directive from the defense attorney check page 25 start with page -- -- five. -- 25 -- the use of deadly force is justifiable Michael done reasonably believes that the forces necessary to prevent imminent death. Are great bodily harm. And we took a poll. There -- two US undecided 24. Was justified in the rest -- are not justified why are we in the others so convinced that Dunn was tilted. We all believed that there was another way out another option what about the testimony -- his -- Run their roar about what he thought about the music to replace. That was a big deal for mean because he testified he wouldn't stay or use the words. -- But he said he would use the words rap crap however in his in interview he did -- got a few times. Dozens DNC -- brawler was grilled by the prosecution. And went to the defendants say. -- -- -- -- -- It is an average tell you he's not a -- with a buyer. Now that -- you think he's not always with a lot. The jurors deliberated for nearly thirty hours there are reports -- there was yelling heard. Coming from the deliberations and there was -- about you did some of the yelling yes. At one point we are all trying to get their point -- -- scream yes. -- -- -- People are passionate about their -- -- yes. What started out on -- one has a ten to vote in favor of convicting Michael Dunn of murdering Jordan Davis ended nine to three. It had to be unanimous. On this trial -- that -- The jury did find -- I'm guilty of attempted murder for shooting at the other teenagers in the car. We did -- and it and it guilty of attempted second degree murder. How could you all convict Michael -- Of attempting to kill the other teenagers. In the car but not convict him of killing. Seventeen year. And that is some. Pretty much my sole purpose for being here because reading the social media. And people looking at us like we didn't do it justice or service we had a lot of discussion on him -- out of the car. And the threat has now gone and your intent is yet to still go ahead and pursue this vehicle. So for you all a dividing line was when he initially fired into the car thinking that there was a weapon that's one thing when the car pulled away -- kept shooting yet. You'll thought everyone thought he crossed a line there yes and that's the exact words used for for lot of -- -- America they would say. White man shoots and kills seventeen year old -- How could not be about race and some. Sitting in that room it was never presented that way we looked at it as. A bad situation. Where teenagers were together and words were -- and and. Lines across the jury was made up of eight whites to blacks Hispanic Indonesia Jordan davis' parents will likely watch this here. -- you say to -- I would say I am sorry of course nothing will bring back their son I hope that they feel that we didn't do them and that this service. Michael -- could well spend the rest of his life in prison. Jordan davis' parents who have a lifetime -- -- As for Valerie any other jurists life -- apps they'll never quite -- saying you think Michael -- -- options. It's -- option should think -- melanoma. Ignore the taunting. Put your car numbers. Back up to the front of the store. Moved the parking spot very. That's my feeling for Nightline -- it is in Jacksonville floor.
This transcript has been automatically generated and may not be 100% accurate.