Produced by Resa Matthews, Mary Ann Rotondi, Marc Goldbaum and Stephanie Slifer

[This story first aired on March 24. It was updated on Oct. 20]

It's a murder case that shook a community and one that hinges on a personal activity tracker and another technology: Google Dashboard, a tool that many people don't even know they have. But could it convict a killer?

Nicole Vander Heyden went out with friends for a night on the town in Green Bay, Wis., on May 20, 2016. She never made it home. A day later, she was found dead in a field, having been beaten and strangled to death.

Nicole Vander Hayden

The murder left her friends and family shaken, and the community wondered how it could happen. At the time, Vander Heyden was living with her boyfriend, Doug Detrie, and their 6-month-old son. Detrie was interviewed by sheriff's deputies and quickly became the prime suspect when blood was found on the floor of their garage and in Vander Heyden's car.

Investigators also wondered why Detrie waited hours before reporting her missing. "It doesn't seem like a guy who's particularly worried about his girlfriend, the mother of his child, does it?" Slinger tells "48 Hours" correspondent Erin Moriarty.

Detrie was wearing a Fitbit device when he was interviewed and when he was arrested. Data recorded about his activities during the window of time Vander Heyden was murdered told a very different story – one that cleared him. He was released 18 days after his arrest.

Over the next several months, Nicole's clothing and items at the murder scene were processed for DNA. That would lead investigators in yet another direction – and to another man.

"Nobody knew who he was," says Kate Briquelet, a writer for the Daily Beast and a native Wisconsinite. "He had no connection to Nikki, no connection to Doug, no connection to any of their friends. I mean, he was literally a mystery man."

A YOUNG MOM VANISHES

Kate Briquelet: Green Bay is supposed to be a really safe place. You know, mothers don't go missing, and … police don't find their bodies in farm fields.

In February 2018, friends and family of Nicole Vander Heyden gather in a packed Brown County courtroom, seeking justice for her brutal, senseless murder, two years earlier.

Kate Briquelet: What happens in this case could definitely come down to the technology.

Kate Briquelet: Who would do this? Who would do this to Nikki?

Tiffany Hoffman was a close friend of Nicole's, who everyone called Nikki. They had been friends for years and shared a love of the outdoors.

Tiffany Hoffman: I was just … it's not real, you know, that can't be…

Erin Moriarty: What's the first thing that comes to mind when you think of her?

Tiffany Hoffman: Light. Spirit. A verve and a zest and zeal. …She was close with her family, and loved her children.

Nikki was a mom to three: Mikayla and Tyler from a previous marriage, and 6-month-old Dylan, whose father was her boyfriend, Doug Detrie.

A cellphone photo of Nicole Vander Heyden and Doug Detrie at the Steel Panther concert. Brown County Sheriff's Office

The two had met in January 2015, and soon moved in together.

Tiffany Hoffman: She was really, really happy. When she talked to me, she said they both were excited. Yeah, they both were excited to have a baby.

On the night of Friday, May 20, 2016, the couple make last-minute plans to get a babysitter and join friends at a bar called the Watering Hole to see a Steel Panther concert.

Kate Briquelet: I think Nikki was really looking to let loose and have a good time.

As the concert is ending, Nikki decides to go with his friends to another bar, called the Sardine Can.

Erin Moriarty: And leave him.

Kate Briquelet: Doug agreed that he would … finish his conversation that he was having and find her at the next bar.

Nikki, seen on security camera video at the Sardine Can, appears to be having a great time, talking and dancing with friends.

But as the night wears on, and Detrie still hasn't shown up at the Sardine Can, Nicole gets upset and begins sending him angry texts.

Kate Briquelet: They were scorching. And they were all but accusing him of infidelity.

Sometime after 11:30 p.m., Nikki tries calling Detrie, but he doesn't answer.

Kate Briquelet: So another friend calls Doug, and he answers. And this enrages Nikki.

So she gets up and leaves the bar.

One of Detrie's friends runs after her, begging her to come back to the bar. But she refuses. Instead, Nicole walks up the street, turns left, and vanishes into the night.

When Detrie finds out that Nikki has left, he and his friend Greg drive around looking for her.

When they can't find her, they go in to the Sardine Can, where Detrie, who can be seen on surveillance video, has more to drink before the two of them head out.

911 Operator: Brown County 911 … where Is your emergency … Richard Vandehey: We just found a human body laying in some weeds

Early the next afternoon, farmer Richard Vandehey makes a gruesome discovery.

Richard Vandehey: At first I thought it was deer, because of the rust color in her hair … then I realized it was a young lady.

Sgt. Rick Loppnow: She was naked. …Other than socks that were on her feet and a pink wristband. …Other than that we had no form of identification

Brown County Sheriff Sergeant Rick Loppnow is among the first to respond to the scene.

Sgt. Rick Loppnow: …there was a lot of blood. There was obvious injury -- trauma on the side of her face.

Sgt. Brian Slinger: Obviously the first step of the investigation is to identify who the person is.

Sergeant Brian Slinger is the lead detective on the case.

Sgt. Brian Slinger: That in and of itself was difficult due to the severity of the injuries.

Deputies get their first lead at 4:30 that afternoon, when Doug Detrie calls 911 to report Nikki as missing.

Sgt. Brian Slinger: Her description matched what we had found in the field as far as age, approximate size -- hair color.

Slinger sends officers with a hidden camera to Detrie's home, which is just a little over three miles away from where the body has been found.

Officer: So you left the Sardine Can and drove around for another 30-40 minutes? Doug Detrie:Yeah we didn't get back here till-- I don't even know what time it was. It was-- it was late. 2:30.

Detrie tells deputies that after Greg dropped him off, he fell asleep around 3 a.m. And except for getting to check on the baby, he was asleep until after 6 a.m.

Officer: Did you do anything to cause her to go missing? Doug Detrie No, not at all.

That night, Detrie's parents watch baby Dylan, while Doug is further questioned at the station. It's here they tell him that Nikki has been murdered.

Doug Detrie: It can't be … no please, no.

As Detrie is being questioned, detectives get a warrant to search his and Nikki's home. They find blood on the floor of the garage … and in Nikki's car.

Sgt. Brian Slinger: on the headboard, on the side and, then, in the backseat area.

They also discover a pair of Air Jordan's in the garage that appear to match the shoe print found on Nikki's back, and seem to have blood smudges on the bottom.

Sgt. Brian Slinger: For us, it's adding up. OK. This-- this is our guy.

Just before dawn, an off-duty patrolman reports items scattered along a highway ramp less than two miles from where Nikki's body has been found.

Sgt. Brian Slinger: There was a purse … as well as her cellphone and … items that she was wearing that night

And there are more damning clues found in a neighbor's yard, who lives across the street from Doug and Nikki.

Erin Moriarty: And what was found here?

Sgt. Brian Slinger: A large quantity of blood that was determined to be Nicole's as well as some clumps of blonde hair … And, then, there was also a cord which I would describe as, a phone … charging cord.

Kate Briquelet: This was a huge discovery for police. …Now they had a murder scene. And it was 118 feet from Detrie's front door.

More than70 pieces of evidence are sent to the state crime lab. Now detectives had a theory about how Nikki had died.

Sgt. Brian Slinger: There was some sort of argument between her and Doug, maybe, when she got home and that … somehow ended up out in the street

Sheriff deputies are recording when they arrest Doug Detrie, who quickly becomes emotional.

Detrie isn't charged with murder, but deputies hold him on a $1 million bond, while they wait for DNA results.

Sgt. Brian Slinger: Is there DNA on the bottom of this shoe? Is that blood on the bottom of this shoe?

Eighteen days later, investigators are stunned. Crime lab tests show the blood in the car isn't Nikki's, the blood in the garage isn't human, and the stains on the shoe aren't blood at all.

Sgt. Brian Slinger: We had nothing on Doug. So he was released.

What's more, on the night Nicole disappeared, Doug just happened to be wearing a Fitbit – a personal tracking device. It goes on your wrist, like a watch, and it tracks your activities: the steps you take, your heart rate, even your sleeping patterns.

When the Fitbit data stored in Doug's phone is examined, it corroborates his story.

Sgt. Brian Slinger: …he had a few footsteps throughout the night … getting up to go to the bathroom, check on the baby, whatever. His story that he told us was absolutely, 100 percent true.

So who killed Nicole Vander Heyden? Will high-tech forensics blow this case wide open?

TRACKING A MYSTERY MAN

Nicole's mother and her brother Brandon struggle to understand how anyone could murder their beloved Nikki.

Vicki Meyer: It was a horrendous thing and it's just so hard to let that out of your heart.

Erin Moriarty: What do you miss the most?

Vicki Meyer: I'm waiting for her to come walking through my door again, you know. I miss her in the most-- I miss her.

Brandon Meyer: I have a picture of … me and her when … we were younger … And just I look at that every night and I miss her all the time.

Remember, the evidence appears to clear Doug Detrie, so in June of 2016, his focus turns to raising his son Dylan, while Nicole's two older children live with their father.

The case torments Sergeants Brian Slinger and Richard Loppnow. They are back at square one, with no idea who did this.

Erin Moriarty: The two of you have this horrific murder on your hands. What are you feeling at that moment?

Sgt. Brian Slinger: We needed to figure out how Nicole got home.

Sgt. Brian Slinger: We pulled video cameras from every single bridge in the city of Green Bay … because in order for her to walk home, she would've had to cross a bridge...

They reinterview witnesses and re-examine phone logs.

Sgt. Brian Slinger: I'll be honest with you, it was getting to the point we worried it was going to become a cold case.

Their first big break comes over the course of the summer. DNA results trickle in -- and they are tantalizing. The officers learn that many of the samples taken from Nicole's clothing and from the neighbor's yard have DNA from an unidentified man. On dozens of samples, the same partial profile -- but never enough for a positive ID.

Sgt. Brian Slinger: We had this one consistent mystery guy, I guess you'd call it. …And our job was to try and find out who that was.

Kate Briquelet: It was just a very confusing time. Nobody knew who would have done this to Nikki.

And then finally, that August, almost three months after Nicole disappeared, the officers get a call from the crime lab. One of the socks Nicole had been wearing has enough DNA to run through the national database – and they get a name.

Sgt. Brian Slinger: The excitement was amazing.

The DNA belongs to a man named George Steven Burch.

Sgt. Brian Slinger: It was a hit out of the state of Virginia.

Erin Moriarty: Virginia?

Sgt. Brian Slinger: Yeah. Virginia.

Sgt. Brian Slinger: So it was like, OK, who is -- who is George Burch? And -- and why is he in Green Bay, Wisconsin, of all places?

Sgt. Rick Loppnow: Yes. We have a name now. But, now, we need to start digging on who this person is.

Burch moved from Virginia to Green Bay on March 1, 2016, looking for a fresh start. A longtime friend gave him a place to stay and helped him get a job. He also loaned Burch a car -- a red, Chevy blazer.

That red Blazer would provide crucial evidence. It had been involved in a hit-and-run accident and destroyed in a fire a few weeks after Nicole's death. So when detectives run Burch's name through the local police database, up pops the accident report, which leads them to an address – for George Burch.

Surveillanance video caprures George Burch smoking on his front porch. Brown County Sheriff's Office

Sgt. Brian Slinger: First time I drove by the house, there he is standing outside in front of the house smoking a cigarette. And my -- my hair stood up on the back of my neck. I had goose bumps. It was like, "Oh my God, there's our guy."

They videotape his movements and keep their suspicions to themselves. And they learn that when Burch was questioned about the hit-and-run, he handed over his cellphone. And on it, a high-tech treasure trove.

Kate Briquelet: He gave them consent to search his phone. They extracted the entire thing.

Sgt. Brian Slinger: So I requested a copy of that. …It's an Android phone. [It] had-- a Gmail account associated with it. We were recently made aware of this Google Dashboard data that could, potentially, give us GPS data.

Most people aren't aware, Google Dashboard is a program that combines cellphone tower data, local Wi-Fi hot spots and GPS locators to calculate the actual location of the phone -- at any given time.

The officers subpoena Google for the contents of George Burch's phone. What they get back is astonishing. Burch apparently spent much of the night Nicole disappeared at Richard Craniums, a bar a half-mile from the Sardine Can.

The data tracks Burch at 2:30 a.m. leaving Richard Craniums, and driving to Nicole's house -- the crime scene -- where he stayed for nearly an hour.

Sgt. Rick Loppnow: …it was very obvious that here's our guy.

He is next tracked at the field where Nicole's body was found, then near the off-ramp where her bloody clothes were discarded, and then, at 4:22 a.m., back at his home.

Erin Moriarty: When you saw that he was right there, what -- what was your reaction?

Sgt. Rick Loppnow: It's a huge piece of evidence, obviously.

Finally -- enough for an arrest – captured on police dashboard cameras.

Sgt. Brian Slinger: we sent one guy out to the house a little bit earlier to get eyes on. …And [he] … called me. …And he's like, "Oh my God … he's on the move. We gotta go now." …We all had to rally up, get in our cars and drive.

Four months after Nicole Vander Heyden's murder, George Steven Burch was arrested and charged with first-degree intentional homicide Brown County Sheriff's Office

On a drizzly September day, four months after Nicole's death, George Burch is arrested and charged with first-degree intentional homicide.

Interrogation room: Officer: The reason you're here … is in reference to a homicide investigation, into Nicole Vander Heyden. So if I read you your Miranda rights, you don't want to talk to me? George Burch: I would prefer a lawyer. Officer: OK.

Nicole's former brother-in-law, Shawn Vander Heyden, says the news came as a big surprise.

Shawn Vander Heyden: I had no clue who he was or where this guy came from … but -- I was just happy to hear that they had -- they had someone.

Nicole's family and friends have a new anguish; waiting for a trial. In March 2017, on what would have been Nicole's 32nd birthday, they came together on Lake Michigan to release lanterns in her honor.

Tiffany Hoffman: It was so cold. So cold. But her memory, you know, warmed us. …we all went out on that dock, on that pier, and lit our lanterns, and sent 'em off in – into -- into, you know, her memory.

Erin Moriarty: Why lit lanterns? Why was that used to honor her?

Tiffany Hoffman:The lights. Her light. She was a light for so many in this world.

Nearly one year later, on Feb. 19, 2018, George Burch goes on trial for Nicole's murder.

The prosecution has a strong case.

Prosecutor David Lasee [in court]: Mr. Burch must be held accountable.

But, according to the defense, prosecutors have the wrong man.

Defense Attorney Scott Stebbins: You will know that Douglas Detrie, Nicole's boyfriend, murdered Nicole.

THE TECHNOLOGY EVIDENCE

For Nicole Vander Heyden's family, every day of George Burch's murder trial is agony.

Erin Moriarty: Vicki, how did you get yourself to go every day to that courtroom?

Vicki Meyer: I don't know. God. He must have just taken our hands and led us there because, we wanted answers.

Friends say it is agonizing for Doug Detrie too, especially once he learns George Burch's defense team is planning to blame Nicole's murder on him.

Shawn Vander Heyden: …he was nervous. And I would be, too. …you know, you were accused of murder, and it's so many things goin' through your head.

And now, Doug Detrie's testimony is critical to the prosecution.

Erin Moriarty: It's kind of interesting that the man who you first thought might have killed his girlfriend is gonna be one of the most important witnesses at this trial. Right?

Sgt. Brian Slinger: Right. …He will be very important.

Just as important would be "the technology evidence" -- data collected from both Doug Detrie's Fitbit and George Burch's phone. Prosecutors say that Detrie's Fitbit shows he couldn't be the killer.

Prosecutor David Lasee [opening statement]: The autopsy results, the DNA identification, the Google Dashboard data, the records from Fitbit … that is the evidence that will drive you. You will follow that evidence and you will find the truth.

Doug Detrie is seen wearing his Fitbit tracker as investigators record him filing a missing persons report. Brown County Sheriff's Office

Detrie's Fitbit is seen in the video captured by officers on their very first interview the day he reported Nicole missing. Prosecutors say downloaded data shows Detrie barely moved in the hours they believe Nicole was killed and left in the field.

Prosecutor David Lasee: Is that based on the data you obtained directly from Fitbit?

Tyler Behling | Forensic crime analyst: Yes it is. Everything that I could view directly on the device it lined up with what had previously been stated.

Erin Moriarty: Did you ever during this trial or have you thought much about it that how lucky it was that Doug happened to be wearing a Fitbit that night and the next morning?

Shawn Vander Heyden: Yeah. …That was huge in this case, I think, right there. …That pretty much said he -- he wasn't there when this all happened.

On day three of the trial, Detrie takes the stand. Prosecutors aim to present him as a normal guy; not the best boyfriend, maybe, but an unlikely killer.

Prosecutor David Lasee: Tell us about your family?

Doug Detrie: My mother, my father, my amazing little son Dylan.

Detrie tells the jurors he and Nikki dreamed of getting married one day. And early on in the night she disappeared, they were having fun. Nikki didn't usually drink, he says, but that night they were both partying hard.

Prosecutor David Lasee: What was the pace she was drinking that night?

Doug Detrie: Pretty quickly. I think she had, like, two down and I was still on my first one.

Once they got separated and Nikki went ahead to the Sardine Can with friends, Detrie continued drinking and smoked some marijuana. Before long, Nikki sent him her first angry text, wondering where he was.

Nikki's texts got angrier, and she accused him of being with other women.

Prosecutor David Lasee: ...at any point in response to those messages, did you get upset with with Nikki?

Doug Detrie: No, I didn't.

The texts kept coming. Detrie said he offered to pick her up, but her phone died.

Prosecutor David Lasee: Were you concerned that Nikki was missing at that point in time?

Doug Detrie: I was -- not concerned that she was missing. I was kinda concerned, like, why is she upset?

Prosecutor David Lasee: Doug, did you have absolutely any involvement in Nikki's disappearance or death?

Doug Detrie: No, I did not.

Under cross-examination, Burch's attorney Lee Schuchart pushed Detrie on whether things at home were really as good as he said they were.

Burch's lawyer shows jurors a text Detrie sent to his mom 10 days before Nikki died:

"I'm very seriously thinking about telling Nikki and the kids they have to move…"

Burch Defense Attorney Lee Schuchart: So in May of 2016, though, there were times where you were seriously considering breaking up with Nikki and the kids?

Doug Detrie: I never really, like, seriously thought about it. Like -- like, made plans or anything like that.

Burch Defense Attorney Lee Schuchart: It was just a lie to your mom.

What the jury would never hear is that several of Detrie's past girlfriends accused him of being jealous, abusive, and controlling.

Kate Briquelet: One girlfriend claims that he put a tracking device on her phone so he'd always know where she was.

Nicole Vander Hayden and Doug Detrie Facebook

In her barrage of angry texts to Detrie that night, Nicole also accused him of being abusive.

Burch Defense Attorney Lee Schuchart: Did you hurt Nikki that night?

Doug Detrie: Do you mean physically or what? I -- no. I mean--

Burch Defense Attorney Lee Schuchart: Did you physically beat her in the past?

Doug Detrie: No, I never physically beat N-- Nikki.

Burch Defense Attorney Lee Schuchart: Had you cheated on her in the past?

Doug Detrie: No, I have not.

Erin Moriarty: Doug is not an angel. Isn't that gonna be a problem in this jury?

Sgt. Brian Slinger: Doug Detrie's not on trial. George Burch is on trial.

Defense attorneys ask the babysitter who took care of Dylan that night, to recount an odd conversation she had with Detrie the day after Nicole died.

Dallas Kennedy | Babysitter: I just asked, "What happened?" you know, "What happened?" and he replied, "I don't know, she hit her head and she just wanted to walk home."

Burch Defense Attorney Lee Schuchart: So specifically, when you asked him what happened, he said that I don't know, she hit her head, correct?

Dallas Kennedy: It came out of his mouth, that comment. I don't know what that meant, but it came out of his mouth.

Would the questions raised about Detrie make jurors wonder if the right man was on trial? And would they buy George Burch's stunning version of what happened that night?



GEORGE BURCH'S STORY

It's day eight of the George Burch murder trial and with it comes the testimony everyone has been waiting to hear: Burch's version of what happened the night Nicole Vander Heyden was murdered.

Kate Briquelet: There was a lot of skepticism about George Burch's story … yet we all wanted to hear it from George's mouth.

Defense Attorney Scott Stebbins: Let's start from the beginning.

George Burch: OK.

Prompted by his attorney, Burch tells jurors he's a hard-working family man with an easy going nickname:

George Burch: Most people call me "Big Country."

Public Defender Scott Stebbins takes Burch back to the night of the murder. Burch claims he ran into Nicole at the local bar called Richard Craniums.

Defense Attorney Scott Stebbins: How were you acting towards her?

George Burch: I was flirting –

Defense Attorney Scott Stebbins: And how was she acting towards you?

George Burch: Somewhat the same pretty much – flirting back and forth with each other.

George Burch takes the stand in his trial for the murder of Nicole Vander Heyden CBS News

According to Burch, they continued flirting until closing time around 2:30 a.m. And just as the Google Dashboard evidence showed, he drove Nicole the eight miles to her house and pulled up to the curb across the street.

George Burch: We sat there and talked for a few minutes.

Defense Attorney Scott Stebbins: OK, what happened after that?

George Burch: Started, I guess, foolin' around, messin' around a little bit, started kissing.

Burch then detailed what he says was consensual sex. Nicole was in the back seat and Burch, too big to fit in the back seat with her, stood just outside the rear passenger door.

George Burch: I was standing outside the Blazer.

Nikki's family and friends had to sit there silently and listen.

Shawn Vander Heyden | Nicole's former brother-in-law: Anyone who knew Nicole knew that that was nothing that she would ever do – ever do – that was not her.

But it's what Burch says happened to him while he says he was having sex that was perhaps the most difficult to accept. He says he was knocked out.

George Burch: The next thing that I remember apart from us having intercourse was literally waking up on the ground outside the truck.

Defense Attorney Scott Stebbins: Did you hear anything?

George Burch: The first thing I heard was, "don't even f------think about it."

Burch said he turned and saw someone standing behind him holding a gun.

Defense Attorney Scott Stebbins: At that point did you know who that individual was?

George Burch: Never seen him before in my life.

Defense Attorney Scott Stebbins: Do you know who that individual is now?

George Burch: Now I do.

Defense Attorney Scott Stebbins: Who was it?

George Burch: It was Doug Detrie.

Burch says he saw Nicole laying on the pavement.

George Burch: I didn't know if she was alive. There was a lot of blood.

The 6'7 250-pound Burch said Detrie told him to put Nicole's body in the Blazer and then drive to the field. Detrie, he said, ordered him at gunpoint to carry Nicole's body down an embankment.

George Burch: That's when I turned and with everything I had I lunged at him and pushed him as hard as I possibly could.

Burch said he ran back to the Blazer and headed for home, throwing Nicole's clothes out the window on the way. The next day, he met up with friends and went fishing.

George Burch went fishinn the day after Nicole Vander Heyden was murdered

Defense Attorney Scott Stebbins: You didn't call 911.

George Burch: No sir.

But he didn't tell anyone else either.

George Burch: You don't tell on people. People get killed all the time where I'm from for that.

As Burch told his story, two women were in the courtroom listening to every word. They had travelled more than a thousand miles to be here every day.

Carla Rhoads: We just wanted him to see our face every day and know that we haven't forgotten what he did. And we've never forgotten Joey.

In 1997, Joey White was murdered in Newport News, Va. The man accused of killing him: Neighborhood rival George Burch. But this jury will never hear about it.

Shayna Stowe: He was out on bond when he killed Joey.

Joey White Shayna Stowe

Shayna Stowe was White's fiancé and mother of his child.

Shayna Stowe: He was my first love. He was it.

Carla Rhoads is Joey's sister.

Carla Rhoads: I miss him a lot.

Burch testified at that trial, too.

Carla Rhoads: He looked at us, laughed at us, you know the whole time. Smirked.

Erin Moriarty: And what happened?

Shayna Stowe: Not guilty.

Carla Rhoads: It was shocking when they said "not guilty."

Neither was surprised that Burch had been accused of another murder.

Shayna Stowe: I'm not shocked at all … I mean I wouldn't be surprised if he's killed other people. I mean look at what he did. I mean it's brutal.

When it was finally District Attorney David Lasee's turn to cross examine Burch he had one thing in mind:

Prosecutor David Lasee: … to show how ridiculous his story was.

And he says he had plenty to work with – like Burch's claim that Nicole would have agreed to have sex in the car.

Prosecutor David Lasee: So Nicole would rather have sex with you in front of her neighbor's home with your butt hanging out of the door of the car, than ask the babysitter to go home.

George Burch: Sir, I don't know. I wasn't the one making decisions.

And if Burch was hit hard enough to knock him out, why didn't anyone see bumps or bruises on his head when he went fishing the next day?

George Burch: I'm 6'7" so it's hard for someone to see the top of my head.

And why would Detrie murder Nicole and let Burch get away?

Prosecutor David Lasee: So rather than just beating you or killing you in the middle of the street he decided to enlist you – a total stranger – to help him dispose of the body of his girlfriend.

George Burch: I don't know what his plans where.

At one point, Lasee pushes Burch on a possible motive:

Prosecutor David Lasee: What really happened was you drove Nichole home fully expecting that you were going to have sex right?

George Burch: I was hoping that we would.

Prosecutor David Lasee: And when you get there and it becomes clear that Nikki isn't going to have sex with you, when she attempts to go into her house and leave your vehicle that's when your mood changes right?

George Burch: No sir.

Prosecutor David Lasee: That's when things get aggressive don't they.

George Burch: Not at all.

Prosecutor David Lasee: That's when you grab that cord and strangle her don't you?

George Burch: No sir, not at all.

Prosecutor David Lasee: That's when Nikki gets slammed on the ground repeatedly when she's trying to run toward her house.

George Burch: None of that is true.

And Burch loses his cool when Lasee presses him on an inconsistency in his story.

Prosecutor David Lasee: So clear this up for me, you're backing down the embankment with Nicole's body in a fireman's carried position, right?

George Burch: No.

Prosecutor David Lasee: What are you doing?

George Burch: I told you before and I will say it one more time for you sir. I was carrying her over to this area…

Shawna Stowe: I think it was a big turn when you saw him lose his temper.

Carla Rhoads: And I think we both said, "Well, there's the real Steve Burch coming out – not George. Not Big Country. This is how we knew him.

Prosecutor David Lasee: You're assaulted, you're held at gunpoint, you carry the mangled body of a woman to her final resting place and the next day you're going fishing with your buddy with a smile on your face and not a care in the world.

George Burch: I wouldn't say not a care in the world. That would definitely not be something I would say.

WHO WILL THE JURY BELIEVE?

The prosecution got one last chance to present witnesses to rebut the story George Burch told the jury.

Sgt. Rick Loppnow: During George Burch's testimony he specifically said, I recall, that they were having sex, her pants were off already at that point. So during the rebuttal, we brought those pants to enter into evidence and make sure they were viewed.

Prosecutor David Lasee: If she had been disrobed in her car, how do those clothes get not just bloody, but dirty and hairy? Those clothes are filthy. And they're demonstrative of being worn during a struggle.

Carefully and respectfully, Sgts. Brian Slinger and Rick Loppnow unwrapped and displayed the pants that Nicole wore the night she died found blood soaked and muddy on the highway.

Sgt. Brian Slinger: It goes to George's credibility, which is zero, that this was not a consensual act … She fought, escaped the vehicle … he bludgeoned her, strangled her with her clothes on, and then transported her body to the scene … His story was a lie … he disrobed her at the scene and forgot her socks.

And then the final arguments: the prosecution reminded the jurors of the weight of evidence against George Burch.

Prosecutor Mary Kerrigan-Mares: Whose DNA is on her sock? …Who is with Nikki at the four key areas of Brown County? …Their explanation is ridiculous and it's insulting to your intelligence.

While the defense hoped to plant doubt.

Defense attorney Lee Schuchart: Justice for Nicole is not going to be delivered by a wrongful conviction of George Burch. Doug Detrie had the motive, the opportunity and the connection to this crime.

Prosecutor David Lasee: The man that met this woman in a bar, and admitted by his own account to dumping her body in that field, looks like this the next day [shows photos of Burch fishing]. Who does that?

Erin Moriarty: What was the feeling in the courtroom as the case went to the jury?

Kate Briquelet: It was very tense … And I was surprised that, I think, 45 minutes later, I mean not even an hour later, the jury had a question.

Jurors asked to see the bloody wire used to strangle Nicole, as well as cords found in Doug Detrie's garage, to see if they were possibly a match.

The jury asked to see the bloody wire used to strangle Nicole, as well as cords found in Doug Detrie's garage, to see if they were possibly a match.

Sgt. Brian Slinger: You know, the fact that they're thinking about that is telling me, 'OK, are they actually believing George Burch's story here?"

Kate Briquelet: It really made me wonder where this was gonna go.

After a nine-day trial and more than 50 witnesses, the jury took just over three hours to reach a verdict.

Shayna Stowe: I just had this horrible feeling it was coming back not guilty … It just was really hard. I could not breathe.

Carla Rhoads: And you could feel everybody was, like, shaking.

Judge: We the jury find the defendant, George Steven Burch, guilty of first-degree intentional homicide

Vicki Meyer: Everybody was just like … Just thank God that he was guilty. Thank God.

George Burch reacts to his guilty verdict CBS News

Sgt. Rick Loppnow: What sticks out in my mind was the gasp … hearing that from the family and knowing the relief that they had at that moment – that'll stick with me.

Erin Moriarty: In a good way…

Sgt. Rick Loppnow [emotional]: Absolutely.

Shayna Stowe: I know Joey was there for this… It was his 20-year anniversary of his death in October. It's just -- trying not to get upset.

Erin Moriarty: Could you see Doug Detrie?

Kate Briquelet: Doug Detrie, I think, was relieved. Doug Detrie was holding his mother. …Doug wasn't even on trial in this case, but he was finally free of any suspicion.

Erin Moriarty: So what you found from this case is that this technology can do more than connect someone to a crime, it can actually exonerate a person.

Sgt. Brian Slinger: Absolutely, yeah. …I feel bad that he sat in jail for 18, 19 days. …I mean, technology is very important and our goal is to exonerate people just as it is to find them guilty.

Kate Briquelet: If we didn't have these Google data locations on George's phone, if we didn't have the Fitbit … Would it be Doug Detrie sitting in prison as opposed to George Burch?

Back in court two months after the verdict, the judge speaks to George Burch before sentencing him, while Doug Detrie and his mother look on.

Judge: ...this family is destroyed and will never be like this again. This is a crime that would, I believe, merit the death penalty and for that you have to die in prison.

In a state with no death penalty, the sentence is as harsh as possible: life without parole.

It is what the families wanted, and yet, this is not a time for celebration.

The only comfort for Nicole's family is that George Burch can never destroy lives again.

Brandon Meyer: When they convicted George … It was a feeling of happiness, but yet still, like, somewhat of a realization that she's actually gone now. And it's hard.

Erin Moriarty: What's the first thing that comes to mind when you think of your daughter?

Vicki Meyer: Her big smile, her big gorgeous smile. …She just radiates. She just does. She was always happy. And that just so reflects who she was.

Erin Moriarty: What do you all tell her children? Michaela, Tyler, Dylan?

Shawn Vander Heyden: Nicole is lookin' over 'em … that she loves 'em, and she'll see 'em again. And every night, I know Tyler and Michaela always say a prayer, and talk to their mom, and say good night.

Tiffany Hoffman: We gained an angel. We lost a breath of fresh air. …The memory lives on through the stories we share, things we never forget and she's okay. She's OK.

Vicki Meyer: She just had a passion for life, for living … She had good morals … Just what more can a mom ask for?

Doug Detrie continues to raise Dylan, now 2.