I refused to live with that level of fear. I had to know.

You did.

Ever since I heard it, it's been replaying in my head over and over. It was all very unbelievable.

It happened on Thanksgiving. Two teenagers missing.

I just buried my head into my hands and I started to CR where.

They were and what they did would launch a terrifying case.

Why did this have to happen here.

With a deadly end?

Nobody's leaving until we figure out what happened.

A man at home, alone and afraid.

They were really attacking his home.

You have a right to protect your home and to protect yourself.

He planned, he prepared, and he was determined to kill.

The most chilling detail of all, what you'll hear on tape.

I'm still.

No one would be the same.

I think that's probably one of the hardest parts about all of it.

I'm Lester Holt and this is Dateline. Here's Kate Snow with 12 minutes on Elm Street.

Twelve minutes, not a long time, but for three people whose paths collided on Thanksgiving Day, 12 minutes was all it took for their lives to explode in a flash.

I refuse to live in fear.

12 minutes that would haunt their families.

I dropped to my knees and I was like, this can't be happening.

Basically why?

Every second of those terrifying minutes would be fiercely debated.

Your natural instinct is to save yourself however you need to do it.

A town divided over what happened inside this house on Elm Street.

I've had a lot of weird things happen in trial. I've never in my life had evidence such as this.

This might be more than what we're initially being told.

But before all the fear and the finger pointing, it was just another Thanksgiving weekend in November 2012 in the small town of Little Falls, Minnesota.

Everybody knows everybody and everything about everybody.

18 year old Rachel Brady was spending the holiday with her 17 year old brother Nick and their 18 year old cousin, Hayley Kiefer. The cousins were inseparable, had been ever since they were little.

We were always together. We would go camping, we were always in the water, always doing something. Me and Hailey were always together.

Nick was the fun, loving one in the group. Kimberly is his mom.

He found joy in everything and he would make sure to find something to make you smile.

He'd just sit there and hug me and be like, oh, Rachel, Rachel, my big sister. And then make me laugh every single time.

Like all kids, they liked to tease each other. Like when Rachel called Nick the nickname he'd had when he was a little boy, Nickel Baby. That like just the family jokey nickname for him. Nobody else called him that just the family.

Oh, no. His like really good friends would call him it after they heard me call him it. He would get so mad at me for saying it in front of his friends.

Growing up, Nick was into sports and loved the outdoors. So did his cousin Hayley, who was as bright and active as he was.

She was vivacious. She was bubbly and funny.

She was very athletic. In high school, she was in gymnastics and softball and track.

The close knit cousins spent the Wednesday before Thanksgiving together. Rachel says there isn't all that much for teens to do in Little Falls. So they would drive around town in the red Mitsubishi Nick rebuilt himself. Would you cruise right down the main drag here?

Pretty much everywhere.

So just spent. Just spending the day with no cares?

Yeah.

They all spent the night together at a friend's apartment on Thanksgiving morning. Nick and Haley left around 11am and.

Then they said they were gonna go to my mom and dad's house.

The plan was to meet later at grandma's house. But Nick and Haley never showed up. Kimberly and Rachel tried calling them. Is it strange for Nick to not answer his phone?

Absolutely.

Even if I would have like called over and over again, he would have called or answered and been like, what do you want?

Strange for Haley to not answer her phone?

Extremely. She would have never not answered my phone call.

So where could Nick and Haley be on Thanksgiving of all days? Adding to their worry was the weather.

It had started snowing, so I'm thinking, okay, the weather. Maybe he got stranded somewhere. And I was hoping that he was just bearing it up and staying overnight. And I try, yeah, in a safe place.

Are you worried about a car accident?

I was very worried.

Nick wasn't experienced at driving in the snow. The family spent Thanksgiving night on edge. And sure enough, on Friday morning, there was frightening news.

We heard about a car accident that had a red car and we thought it was him right away. And so we went and looked and it ended up being car pieces for a different car. And so then when that wasn't him either, we started to get extremely worried.

We drove up and down the back roads though. I mean, up and down the highway, any way I could think of anywhere.

Rachel posted messages on Facebook. Has anyone heard from Haley or Nick? Still nothing. By Friday afternoon, they were out of their minds with words.

I mean, we called and called and called. No answers, no nothing. We kept getting the voicemails and I was like, nick, this is getting serious. You know, we.

I started crying on one of them and I was like, you better not be making fun of Me.

This better not be a joke.

Yeah.

Before the day was over, the family would find out this was no joke. Something terrible had happened to Nick and Haley. But it wasn't a car crash or an accident. It was something no one in Little Falls could have seen coming.

I tried to be a good person.

Across town, there was concern too. When we return, just worry and panic.

It's like something's wrong.

Someone else had also met with trouble that Thanksgiving Day. The deadly kind.

The Friday after Thanksgiving 2012. Kimberly Brady was worried sick that her son Nick and her niece Haley never showed up for Thanksgiving dinner. They'd been missing for more than 24 hours. Did you have a mother's intuition?

I just saw. I knew something was wrong. I was just so unlike Nicholas.

By Friday afternoon, the family was frantic. So you decided to call the police?

We went in.

We went in to the sheriff's cars.

Right away and filled out missing persons reports for both of them.

As authorities processed those reports, three other sheriff's deputies were over on Elm street investigating something so troubling, they later called in a crime scene van. That got the attention of John and Kathy Lang, who saw the van go straight towards the house of their good friend Byron Smith, a 64 year old retired man living on his own.

I was decorating the Christmas tree. I saw a big, huge truck go down his road, called the Bemidji Crime Scene Unit. And I shouted for John, I think you were in the kitchen. And I said, call Byron's cell. Something has happened.

What did you worry Kathy? What did you think had happened?

I thought he was dead.

Kathy and John feared the worst for their friend, who'd seemed out of sorts in recent months. Everything was fine when Byron first moved back to his hometown of Little Falls about five years earlier after a career that took him all over the world with the US State Department.

He was talking about living in Moscow, in Cairo and Dakar, and it's amazing. A worldly guy, very much so. A great conversationalist and fun to talk with.

But recently, Byron wasn't himself. His house had been broken into a few times. The thieves taking everything from money to precious family heirlooms. The Langs say their friend who'd mentored Boy Scouts and let their son's rock band jam in his garage, had become afraid. He was acting real quiet, real scared. And then that crime scene van showed up outside Byron's home. And Kathy was sure her friend was in trouble.

Just worry and panic. It's like something's wrong.

She was right. Something was wrong. Burglars had struck again. This time, Byron was home, and he had a gun. He'd managed to defend himself and survive the break in.

If you break into somebody's home, you better not have an expectation you're going to walk out alive because the law permits them to shoot you.

Mickel Wetzel is the Morrison County Sheriff. Byron told his deputies that he'd been in his basement in his reading chair when two intruders broke into his house and crept downstairs. Byron shot both of them dead.

Minnesota law is clear on this thing. You have the right to use deadly force against another person. If you believe your life or the life of another is in immediate jeopardy.

As investigators continued to secure the scene at Byron's house, the sheriff's office was calling another family. Kimberly Brady had been frantically trying to find her son Nick and her niece Haley. Now investigators knew what had happened to them. They drove out to speak with Kimberly, and they brought a chaplain.

As soon as I saw them turn the corner that something. I knew he was gone. I didn't know how or why. And then all of a sudden, I remember the door opened and the chaplain came out. All I said was, no. I don't really remember if I said anything else. He's like, your son is dead.

Nick and Haley were both dead. Kimberly fell to her knees. And then the chaplain told her it was no accident.

He's like, your son was shot. And I was like. And then I mean, shot. That just wasn't.

Doesn't fit.

I just remember feeling like. I said, what do you mean shot to death? When I could finally get something out. And they said, well, he was shot three times.

I was like, shot?

What do you mean, shot three times? And that was. I couldn't function. I couldn't really hear after that.

Were you there, Rachel?

During that, I walked in, and then my dad said that somebody. Somebody shot Nickel baby. And I remember I just went right outside and I sat in the snow and I just buried my head into my hands, and I started to cry. And then he tapped me on the shoulder and told me, haley's gone, too.

That's your brother and your best friend. Do you remember what was racing through your head, Rachel?

Basically, why? I guess we all just couldn't believe it was both at one time.

So suddenly, even harder to absorb how and where Nick and Haley were shot. They were the intruders Byron Smith killed.

It was all very unbelievable.

So what happened in that basement on Elm Street? The answer to that would lead to a heated debate. How far is too far when it comes to Defending your home. When do you cross the line between victim and criminal?

Coming up, what had Nick and Haley been up to? A grainy image captures a clue. Is that Nick?

You see him on different cameras, different angles, walking around the house.

Is that Haley? Deputies are about to learn something puzzling.

Why in the world are we only hearing about the shooting of two people.

A day later, When DATELINE continues.

The story of what happened on Elm street spread quickly around Little Falls, Minnesota, that two teenagers had broken into Byron Smith's house, leaving the terrified homeowner no choice but to shoot them in self defense. His friends and neighbors, John and Kathy Lang, had no trouble believing it.

What was scary, it was very personal to him because they were really attacking his home.

But the family of those intruders, they were in shock.

I didn't believe it. I thought it was completely not right or untrue.

Teenage cousins Nick Brady and Hayley Kiefer had gone missing the day before Thanksgiving. Now, as she learned the circumstances of her son's death, Nick's mother had so many questions. How do you reconcile in your head your beautiful boy who loves the outdoors and what they're telling you, that he broke into somebody's house?

I just. I couldn't imagine it. It just was so not him.

So you just couldn't reconcile him?

Yeah, I had a lot of trouble.

Kimberly had never heard the name Byron Smith, but Rachel had.

I knew that my brother had worked for him in the summer, but I didn't know him at all.

Nick had once done yard work at Byron Smith's house. Now the sheriff had evidence of what he was doing there. Again, Byron had set up surveillance cameras at his home. Frightened after a string of break ins, those cameras proved there was no mistake about the break in. Just after 12:30, the cameras pick up a man approaching the house. The hooded figure is Nick. He looks through several windows as if checking to see if someone's home. He clutches his hood closely concealing his face. Jeremy Lubertz is an investigative sergeant with the Morrison County Sheriff's Department.

You could see that there had been what appeared to be a little bit of casing done on Nicholas Brady's part.

He even heads toward one of the cameras and tries to dismantle it. Then he walks out of camera range, shatters a window and enters the house. Minutes later, the camera shows another hooded figure, this one carrying a purse and a cell phone.

It's Haley on the video. It shows that the female had come walking up through the yard up towards.

The house, all on tape, clear as daylight but why? What were Nick and Haley up to that day? They both went to my school at one time. Dylan Lang is the son of Byron's friends, John and Kathy. What did you know about those two teenagers?

I knew that Nick was aggressive.

He would be the kid who would.

Push you up against the locker and.

Kind of a bully, right? He was a bully and as it turned out, a thief. After the shootings, authorities determined that Nick had been behind one of those previous burglaries at Byron's house. Just a month earlier, he and a friend broke through this door and stole thousands of dollars in cash and priceless family heirlooms and more disturbingly, two guns. They took things that were really important to him personally, and then when he took the guns, he thought he was going to get shot by his own guns. He was extremely afraid. To Sergeant Lubertz, it all looked like a classic case of troublemaking kids crossing a line into dangerous criminal behavior.

You have two teenagers that seemed to be running kind of rampant. You can obviously see that they had a change in their lives.

The evidence appeared to all be there, clearly captured on that surveillance video. Nick and Haley had broken in, and Byron Smith seemed to have every reason to be afraid.

The impression that he kind of left on me was that he was living in fear. He was not sleeping. It was obviously bothering him physically and emotionally at first.

Even Nick's mom, while she didn't want to believe much of what she was learning about her son, tried to imagine herself in Byron's shoes.

I don't believe that breaking entering is right, and I wouldn't have expected it out of my son.

It looked like a tragedy all around. Two intruders and a fearful homeowner with no choice but to shoot them.

We know you have a right to protect your home and to protect yourself.

But a quick survey of the scene told Sheriff Wetzel that the teenagers were unarmed. As with any shooting, it would require more investigation.

It would be ordinary. With two people dead in a home that nobody's leaving until we figure out what happened.

Beginning with one question, a pretty big one.

Why in the world are we only hearing about the shooting of two people in a house a day later?

It turns out Sergeant Lubertz and other deputies had rushed to Byron Smith's house Friday afternoon, only to learn that the break in and shootings happened Thursday on Thanksgiving Day.

I asked him, I said, why didn't you call law enforcement? And he tells me, I didn't want to bother you guys on Thanksgiving Day.

That struck the sheriff as extremely odd.

Nobody Worries about wrecking our Thanksgiving. They don't worry about wrecking our day.

So the intruders had been dead for 24 hours when Byron called a neighbor for help and asked him to call the sheriff's office. When you found out that Byron smith had waited 24 hours, my mind was.

Then, why, if he was so scared, wouldn't you be on the phone? I mean, because those kids had families too, that were waiting.

And then for him to say he didn't want to bother anybody on Thanksgiving, really.

It became clearer and clearer and clearer that there were some things that were strange about this case.

Investigators were about to learn a lot more about that shooting in the house on Elm Street. And what happened next would tear this town apart.

Coming up, I was no longer willing.

To live in fear.

Byron Smith's story, was it all adding up?

You would think after such a horrific event, you would be very emotional, maybe crying. I didn't notice any of that.

Nick Brady and Haley Kiefer had broken into Byron Smith's house. The frightened homeowner said he'd shot them in a moment of self defense. But investigators had questions for Byron, so Sergeant Lubertz escorted him down to headquarters right away that Friday.

Can you tell me your full name, please? Byron David Smith.

I just wanted his story, you know, I wanted to find out the rest of the facts of what happened at the house.

Whoever it was who was breaking into my home had been doing it for so long that I was no longer willing to live in fear.

Byron explained how he'd been terrified ever since that break in a month earlier when two of his guns were stolen.

These are people who have stolen my guns. I figure they're willing to use guns if they steal guns.

Byron wasn't home during those other break ins, but this time he was as seen on this home security camera. He said he'd moved his truck a few blocks away that morning so he could clean his garage. The teens must have thought he wasn't there.

I needed to clean out the garage and I wanted it out of the way for a while.

Byron told him how he was in the basement when he heard the first intruder break in upstairs and head down toward him.

That you heard footsteps coming down the stairs, is that correct? Yes. And then I saw his feet and then I saw his legs. And when I saw his hips, I shot.

It was Nick. Byron shot him three times.

I was reacting. Okay. What were you reacting to is what I'm asking. The threat. The previous losses. I spent 20 years overseas. A couple years in Bangkok, several years in Cairo, 20 years overseas, not one problem, and I retire to my peaceful hometown.

While Byron's voice broke a few times during his account of the shooting, Sergeant Lubertz was surprised at how calm and matter of fact he was for most of the interview.

You would think after such a horrific event, shooting and killing two people that broke into your house, that he would be very emotional, maybe crying at times. I didn't notice any of that from Byron Smith. He just maintained his composure, which was rather odd.

Much stranger still, the investigator thought, was Byron's account of what happened. A few minutes after he shot Nick Haley entered the house and Byron fired again.

You jammed trigger clicked and she laughed at me. I just pulled out the.22 and shot her. If you're trying to shoot somebody and they laugh at you, you go again.

Was Haley really laughing as he shot her? To the sergeant, it seemed like such a bizarre detail. And then Byron told them this.

I thought she was dead and it turned out she wasn't. So I did a good clean finishing shot.

He shot Haley six times in all. And with that, the investigators came to believe this was something other than a simple case of self defense.

My question, Byron, is why did you shoot again? She didn't have a weapon in her hand. She wasn't actually. I don't know if she had a weapon in her hand until later. I wasn't looking at her hands but.

She was laying there hurt.

Did she? She wasn't threatening you? I'm just asking. She was threatening me.

There was certainly a continuation of the use of deadly force after it appeared to us the threat had stopped and that made us believe that this needs to be looked at by the prosecuting attorney.

Byron Smith was arrested that day, but later released on bond. A grand jury was convened to look at the case in Little Falls. His friends were shocked that authorities could believe Byron was anything but an innocent victim.

It was ridiculous that he would be this cold blooded killer. Like really, he's a quiet, soft spoken person. I just didn't fathom it.

While Byron was free on bond, his friends, the Langs, say he couldn't bear to go back to his own home. So they took him in. I could hear him in his room many, many nights. I'm so sorry. I feel so bad. I didn't want to hurt anybody. I could hear him in there crying. The case quickly became a big controversy in Little Falls, Minnesota. Do people take sides?

Absolutely. People became more opinionated about what happened.

Some people would come up to me, he's going to prison. He shouldn't have done that. And I said, well, you haven't heard the whole story.

I think that Byron's got a lot of support in this area.

Bill Anderson is Byron's neighbor, the same one who called authorities the day after the shootings.

Myself, would I have done the same thing that Mr. Smith did? No doubt in my mind. No doubt in my mind. It seemed like a big box of puzzle pieces.

Prosecutors Pete Orput and Brent Wartner were in charge of evaluating the case against Byron. And they knew it was controversial from the start.

When Brent and I got involved in it, the emails started, the phone calls castigating us for taking this. After all, doesn't a homeowner have a right to defend his dwelling? You know, I didn't argue with people. I just said, well, just stay open and let the evidence come out. And then let's see if you hold that same view.

After looking at all the evidence, the prosecutors believed there was a strong case the moment Nick broke the window and entered into that house. Didn't Byron Smith then have the right to defend himself?

Yes, yes, he did. But that's not what he did. He went way, way beyond defending himself.

That grand jury in Minnesota agreed. In April of 2013, five months after the shootings, Byron Smith was indicted on two counts of first degree murder. Now there would be a trial in the case everyone in town was talking about, with revelations from both sides coming up.

I've tried a lot of murder cases and this one seemed like a real challenge.

Why?

Because a lot of people thought we'd lose it.

Murder or self defense?

Why did he wait so long before calling?

Authorities fear the explosive debate heads into court when DATELINE continues.

Byron Smith's first degree murder trial got underway in April 2014. And just like. Like the town itself, carved in two by the mighty Mississippi river, the people of Little Falls, Minnesota found themselves divided. On one bank stood those who saw Byron as a cold blooded killer who fired nine shots at two unarmed teenagers. When you're talking about multiple shots down on the ground, right away jumps out at you, you know, hey, this is premeditated murder. On the other bank were those who viewed Smith as a man with every right to defend himself and his home against intruders.

They weren't invited for Thanksgiving dinner. There wasn't a table set for them. They didn't come through the door, but they certainly found a window to come in.

But Nick's mother, Kimberly Brady, was determined, even through her own grief, not to make up her mind until she'd heard all the facts.

I kept an open mind because if he was fearful for his life, I couldn't fault him for defending himself. I waited until I heard all the evidence.

The evidence said Byron Smith's defense attorney, Steve Meshbescher, would show his client had done nothing wrong.

This is a case about big misunderstanding. This is about Byron Smith being accused of a crime he did not commit.

Did you believe that Byron Smith was justified in shooting Nick Brady and Haley Kuiper?

Yes. It's not something he wanted to do, but he didn't ask them to burglarize his home in a violent way on Thanksgiving. They chose to do that and he reacted.

So the defense came to court confident a jury would see it that way. In Minnesota, as I understand it, you have the right to protect your life. You have the right to protect your home, your property, as long as it's reasonable.

If somebody breaks into your home and commits a felony offense in your home, you can kill that threat.

Meshbescher said that everything Byron did that Thanksgiving Day and the next was evidence that he was truly terrified inside his own home. Why did he wait so long before calling authorities?

Fear. He was afraid. There was a third or fourth or fifth person. So he's afraid of the backyard, the front yard, the stairway, the door. He's just in utter fear. And he goes in a closet and hides in his own house until the fear subsides.

As for Smith's calm demeanor and the matter of fact way in which he described the killings.

And you're pulled out the.22 and shot her.

On the exterior he appears to be calm, but he's talking about how frightened he is internally. He's trying to explain to the police what happened. He's trying to help them solve what occurred.

But would the defense be able to convince the jury that Byron Smith's own account of the shootings, how he gave Haley a self described finishing shot, was really justified?

I did a good clean finishing shot.

From a human standpoint, it just sounds so cold blooded.

It does. And I had to deal with the way it sounded. But it's not evidence of what he's thinking. It's evidence of emotion. It's not evidence of murder.

Meshbescher thought his strongest evidence to justify the shootings was the fact that Nick Brady had broken into Byron Smith's house before, had even stolen guns. So Byron had every reason to fear for his life. You wanted to show them that these were kids that were up to no good.

No, that's not what I wanted to do. I wanted the jury to see the Truth rather than just see a painted picture that the media was playing of their high school photographs.

But the judge said testimony about Nick's involvement in that previous break in was irrelevant and inadmissible. Mesh Bescher also couldn't say in court that there was evidence that Nick and Haley together had robbed another house, too.

Unfortunately, the judge would not allow that evidence to come in. And I thought he was making a grave error.

And so Byron Smith's friends watching in court could only hope that the jury would see things as they did, that he was a scared man who defended his life and property.

We knew him as our friend Byron, so it was ridiculous to us. For authorities calling him a cold blooded.

Killer, it would be an uphill battle in the court of public opinion, thought Prosecut. They knew they had the burden of proof.

I've tried a lot of murder cases, and this one in particular seemed like a real challenge.

Why?

Because a lot of people thought we'd lose it.

A lot of people saw this as a referendum on whether it's okay to protect your property and protect your life. You don't see it that way.

Not this case, not these facts.

But to prove murder in the first degree, the state would have to show that Byron acted not just with excessive, unreasonable force, but also with premeditation. And while the defense may have had a lot of townspeople on its side, the prosecution had something else. A piece of evidence they felt would sway any juror to see Byron Smith not as a fearful victim, but as a calculating killer. Did. Did Byron tell investigators that he had made audio tapes?

No, he did not.

Coming up.

You're dead.

The revelation that stopped everyone cold. Those 12 deadly minutes heard on tape.

Can you ever erase that from your memory?

Not ever.

There are people who think Byron Smith is a hero. What do you say to them?

I say he's a murderer. And murders can't be heroes.

In a sharply divided Minnesota courtroom, the prosecution argued that Byron Smith was no fearful, innocent victim, but an angry man bent on violent confrontation. He told investigators from the beginning that he was sitting reading a book in the basement, that he was caught unaware. You don't buy any of that?

No, not at all.

The prosecutor said they had evidence that it was premeditated murder. They told the jury Byron had set a trap for the burglars. Remember the story about moving his truck to clean the garage? The prosecutor said that was a lie, that Byron had in fact moved the truck to make it look like he wasn't home. You think Byron wanted to catch the people who had Been breaking into his house.

Clearly he planned, he prepared, and he was determined to kill whoever is breaking into his house and stealing his property.

The prosecution said Byron was in the basement not to read a book, but to wait like a hunter.

It just seemed like Byron Smith was deer hunting, like a lot of folks do in Minnesota, where you get in your stand and you wait and you wait, and when a deer comes by, you shoot and kill it. And it just seemed like that's what he did with these kids.

But could they prove it? Turns out the prosecutors had something they'd never encountered in nearly half a century of combined trial work. Do you remember when you first listened to it?

I do, and it knocked me out. I've never been able to hear a murder actually occurring.

Byron Smith had recorded the break in and the shootings. Investigators found this digital audio recorder on a bookshelf in the basement. It had captured more than six hours worth of audio that day. You ended up with a trove of information, his own words on tape.

Indeed we did.

Here is Byron Smith, shortly before the break in, talking to himself.

You're the last guy in your left eye. Why would he say that a half hour before anyone came over? Well, when you go through the autopsy photographs, you see that he shot Hailey Kiefer in her left eye.

He was planning where he was going.

To shoot an intruder, not just shooting him, but where. Where in the face is he going to shoot him?

Then it sounds like Byron is planning not just the shooting, but also his defense. He practices contacting a lawyer.

I realize I don't have an appointment, but I would like to see one of the lawyers here.

Ten minutes later, the practicing is over. The recorder captures something real. How quickly did everything go down that day?

12 minutes.

12 minutes from the first shot fired at Nick Brady to the ninth and final one fired at Haley Kiefer.

It was frightening.

The Prosecutors played all 12 minutes in court, but first warned Nick and Haley's families, who sat through every day of the trial, that they may not want to hear it. He actually suggested you probably shouldn't be there that day.

He did? More than once.

Why did you want to be there?

I needed to know. I mean, you need to hear the whole story to understand it. I think in this case, you can't just make a snap judgment.

This is the sound of Nick entering the home, walking down the stairs to the basement.

And as he's going down the stairs, you can hear him get shot.

We won't play that part of the recording, but listen to what Byron says. After shooting Nick three times, you're dead. You can then hear Byron reload his gun. Ten minutes go by, then the recording picks up a whisper. It's Haley coming into the house looking for her cousin.

So she comes in and goes right to the basement. Starts walking down, and that's when he shoots her.

Here on the recording is what the prosecution says is a pivotal moment. In his interview with investigators, Byron had said he felt threatened by Haley and that she'd been laughing at him when he fired.

She laughed at me.

But on that audio recording of the shooting, which again we have edited, the prosecution says Haley clearly sounds terrified.

Oh my God.

She's screaming in a high pitch, saying, oh my God. Oh my God.

And after he's done shooting, this is what Byron says. Those in court saw Byron Smith wipe away tears as the audio played. There was stunned silence, save for the quiet sobs from Nick and Haley's families. Can you ever erase that from your memory?

Not ever.

I think ever since I heard it, it's been replaying in my head over and over. I feel like anytime I hear somebody say, oh my God, that's what I think of.

But the prosecution wasn't done with that recording.

Cute. I'm sure she thought she was a real pro.

Because Byron continued to talk to himself after the teens were dead.

I felt like I was cleaning up a mess.

I don't see them as human.

I see them as vermin.

What do you hear when you hear those words?

Pure evil. I don't know how you can say that about anybody, let alone two precious kids. And I don't believe he was scared. I believe it was premeditated murder.

But in court, the defense said that recording, as disturbing as it is, proves no such thing.

I tried to be a good person.

Rather, it shows a man quite possibly driven mad with fear.

I feel a little bit safer. Not totally safe. I'm still shaking a bit.

He's talking to himself, mumbling things. A lot of things didn't make sense.

He sounds frankly like someone who's maybe losing his mind.

Someone who's or lost their mind. He simply had no ability to deal with reality at that time.

After a week of testimony, the case went to the jury. It was anyone's guess which portrait of Byron Smith those 12 people would believe. The cold blooded killer lying in wait or the terrified man under siege in his own home. What were you thinking as the jury went out to deliberate?

I gave it all to God. I was pretty peaceful.

Just put your faith in him.

I did.

And waited and waited it wasn't a long wait. The jury was back in less than four hours. The verdict, guilty of first degree murder for killing both Nick Brady and Hailey Kiefer.

I waited, I heard, then I believed, and then it was said.

I was very happy to see him taken away, but there was no winners.

It doesn't give you your brother and your best friend back. Exactly. But Byron's supporters felt the opposite of relief.

Shocked, stunned.

Well, it was such a one sided trial. It was so unfair. Kathy says there's so much more to her friend. The jury never learned.

He just came here to retire and want a quiet life. This should have never happened.

It was just 12 minutes that changed so many lives in so many tragic ways. Byron Smith will live out his retirement in prison having received an automatic life sentence. And Nick Brady and Hayley Kieffer, two young cousins who made a terrible decision to enter that home, paid for it with their lives. And their loved ones are left to mourn a future that will never be. You had a little baby girl not too long ago and Nick and Haley weren't here to see that.

I think that's probably one of the hardest parts about all of it. I would have loved to see my brother hold her.

He would have been Uncle Nick.

Uncle Nickel, baby.

That's all for now. I'm Lester Holt. Thank you for joining us.