When she brought her car to the repair shop he managed, Dave Kroupa was attracted to Cari Farver right away.

So when the automotive technician ran across her profile on a dating site a few weeks later, he made his move.

Cari, a 37-year-old computer programmer, was "smart and sexy," Dave recalled in the new Netflix documentary Lover, Stalker, Killer. "Out of my league all the way around."

But "wild and free at 35" after breaking up with the mother of his two kids, he wasn't looking to get serious with anyone. And Cari's profile fit the bill, the divorced single mom of a teenage son writing, "Just looking for a fun, casual relationship."

She also happened to work just three blocks away from his Omaha, Neb., apartment, so they started spending time together.

All seemed to be going great when, two weeks into their whirlwind romance, Dave left for work early on the morning of Nov. 13, 2012, kissed Cari goodbye, and then got a text from her at 10:30 a.m. reading, "We should move in together."

As he recalled in the doc, when he balked at the suggestion, he was met with a barrage of texts from Cari: "Fine f--k you...You've ruined my life...I never want to see you again."

When Dave returned to his place at lunchtime, Cari and all of her stuff were gone.

He was admittedly sad, yet "tried to get on with my life like nothing happened."

Dave never saw Cari again. But this shocking scene was only the beginning of the years-long nightmare unpacked in Lover, Stalker, Killer. And when he finally found out the truth, Dave said, it was "such a mindf--k."

Shanna Elizabeth "Liz" Golyar was the first woman Dave Kroupa connected with online after he decided to dive back into the dating pool. He had moved to Omaha in 2012 because that's where his ex-girlfriend Amy Flora decided on and he wanted to be near their two kids.

Liz—a 34-year-old divorced mom of two who owned a housecleaning business—was "very smiley, energetic, full of life," Dave said in the doc, and they had a good time together. He said he was upfront with her from date one about wanting to keep it casual.

About six months after he met Liz, Dave met Cari Farver, first seeing her when she showed up at the auto repair shop he managed and then connecting online. "When we looked at each other," he told ABC News in 2020, "there was a little spark."

In the doc, Dave said he was enamored by Cari's "spirit and her drive," impressed that she'd gone back to school after having her son, Max, at a young age. "She was just trying to make her way in the world," he said.

At the time it didn't seem that weird when, the first time Dave brought Cari back to his place, Liz showed up, explaining that she needed to get some things from his apartment.

Liz only saw Cari for a few seconds before he ushered her out, Dave recalled in the Netflix doc. Cari left but invited him to her house in Macedonia, Iowa—a small town (pop. 267 in 2020) just over the Nebraska border—instead. He took her up on it and they spent most of the next two weeks together. 

So call Dave surprised when, after their fling ended, he started getting increasingly menacing messages from her, first just from her phone number and email address, and then from dozens of numbers and email accounts.

Cari's mother, Nancy Raney, said in the Netflix doc she last saw her daughter on Nov. 11, 2012. At first she wasn't too worried, knowing Cari had met someone and was probably just busy. But after Cari didn't show up for a family wedding, Nancy reported her missing—which led to sheriff's deputies paying Dave a visit.

When Dave showed them the messages he'd been getting, he recalled in the doc, the plot thickened.

Nancy told police that Cari was diagnosed with bipolar disorder and had battled depression in her 20s. Cari "had been seeing therapists and was on medication," Nancy later told ABC News, though there were periods when she stopped taking her meds.

After she'd filed the missing person report, Nancy said in the Netflix doc, she got a Facebook message purportedly from Cari, saying, "I am not missing, I just don't want to come home right now. I love you all very much but I need time." Meanwhile, Cari's 14-year-old son Max was staying with Nancy.

Her daughter also texted on Mother's Day, Nancy said, but then the messages got steadily "nastier."

The investigation into Cari's disappearance took a turn when Liz showed up at Dave's place to show him that her car had been keyed. Cari had also been texting about her, Dave recalled in the doc, calling her a "whore" and vowing to do more than scratch up her car.

Cari was "clearly jealous of Liz," he said.

Dave also got texts from Cari that implied she was watching him, such as "How's that coffee taste?" while he was sitting at a diner and threats to "go after" every female customer he interacted with at work. 

Former Omaha Police Detective Chris LeGrow said in the film that the case seemed fairly "routine" at first, that they were seeing the "initial phases of stalking."

The messages kept coming and, as detailed in the doc, Cari texted Dave a photo taken from inside Liz's house. "Whore" was spray-painted on a wall in the garage.

Wanting to protect Liz and her children, Dave acknowledged in the doc that they "rekindled" their relationship amid all the stress.

At the same time, the mother of his kids, his ex Amy said she didn't want the children at Dave's place while he was embroiled in this situation. (Amy and their children also ended up on the receiving end of threatening messages from Cari, as would seemingly every other woman he knew and spent any time with. A high school friend of Dave's, Heather Twedt, told ABC News someone threw a brick through her window while he was over one night in January 2014.)

Months after Cari disappeared, Liz called Dave to say one of his windows had been smashed. "Go away whore" had been scrawled in red lipstick over the bed and some of Liz's clothes were lying there, looking as if they'd been slashed with a knife.

In August 2013, Liz's house caught fire. Her kids weren't home at the time, but her pets—two dogs, a cat and a snake—were killed. Not long after, she moved away and didn't tell Dave where she was going, he recounted in the doc. As for Dave, he acquired a gun, which he kept in a case on a high shelf in his closet.

By the spring of 2015, Dave and women he knew were still being threatened but, aside from the steady stream of texts and emails, there was no trace of Cari. 

"There was no proof really that she was alive," Pottawattamie County Sheriff's Office investigator Ryan Avis recalled in Lover, Stalker, Killer. Their interest piqued, Ryan and his good friend Sgt. Jim Doty asked to be assigned to the stalled case—and once they got it, they dug in for the long haul.

Other than two debits from Cari's bank account made Nov. 19, 2012—six days after Dave saw her last—there'd been no other activity. And, as Jim noted in the doc, "It's hard to exist without money.

He and Ryan enlisted the help of IT specialist and volunteer deputy Tony Kava—a Soylent-drinking computer whiz who put off having brain surgery at one point because doctors told him it would affect his work on the case—to trace where the hundreds of thousands of text messages and emails had come from.

And Tony, using a program he wrote himself to narrow down the IP address, cracked it. He found the digital footprint linked to the home of Todd Butterbaugh, a fellow county employee (who actually worked for Tony, small world). When questioned, Todd said his on-again, off-again girlfriend had been living with him ever since her house burned down.

"We believed that Liz was the victim," Ryan said in the Netflix doc. "It's not true. In fact, Liz is the stalker."

Dave recalled crying when investigators delivered the news. "It was such a mindf--k," he said. And "it didn't take me long, checking the boxes in my head, to come to the conclusion that Cari was probably dead."

Unable to prove anything other than Liz had been impersonating Cari, the investigators kept digging. On another dive through Liz's phone data, they found a photo of Cari's Ford Explorer. The vehicle had been in police custody since Jan. 8, 2013, and a single unidentified fingerprint had been found on a mint container in the center console.

Now with something to compare it to, analysts found the print belonged to Liz.

Around this time, Dave said in the doc, he came home one night to find his gun missing.

On Dec. 5, 2015, 911 got a call from a woman who said she'd been shot by another woman at Big Lake Park, near the Pottawattamie County Sheriff's Office. 

The woman with the gunshot wound was Liz, and she told authorities she "wouldn't put it past" Dave's ex Amy. She proceeded to start forwarding emails to the sheriff that were supposedly from Amy, in which Amy confessed to shooting Liz. 

In the doc, Ryan—already sure Liz shot herself—recalled advising Dave to move back in with Amy. To protect their children, yes, but also to elicit some "raw emotion" out of Liz.

Soon enough, the investigators said, the emails Liz claimed to be getting from Amy escalated to what sounded like a confession to murder: They described stabbing Cari in her car, parking in an abandoned lot, covering the body with a tarp and burning it.

Authorities returned to Cari's Explorer to look for blood. An initial sweep with a black light turned up nothing. They cut into the fabric around the driver's seat and found nothing. Then they pulled off the fabric from the passenger seat and found a big red stain.

Liz was arrested and promptly denied—as seen in interrogation footage included in the doc—ever being anywhere near Cari's car or even seeing it.

The detective questioning her asked, "Are you going to sit in this chair and be remorseful, or are you going to sit in this chair and be coldblooded?"

She also denied ever creating or sending any of the emails in question and asked for her lawyer.

Chief Deputy Brenda Beadle of the Douglas County Attorney's Office admittedly found the story "really hard to believe." In the doc she remembered thinking, "Who's gonna shoot themselves in the leg, for crying out loud?"And the prosecutor still needed more evidence if she was going to put Liz on trial for murder.

IT expert Tony recalled asking Dave if he had any old electronic devices from around the time Cari disappeared. Dave found a long-dead tablet in his storage unit. Tony took out the memory card and, finding nothing on it, mined it for deleted files.

He soon realized he was looking at the contents of Liz's phone from that time. And amid all the selfies and other photos, Tony said, there was a pic of what he thought at first was a piece of rosewood. Upon closer inspection, however, he saw that it was a foot. A quick glance at his copy of Gray's Anatomy showed him the foot was in a state of decomposition known as venous marbling. 

Cari's mom Nancy confirmed her daughter had a tattoo on her foot, just like the one in the picture: The Chinese symbol for "mother."

Liz was charged with murder on Dec. 22, 2016.

She pleaded not guilty, her defense counsel disputing whether a murder had occurred at all since there was no body.

But the judge—the defense having opted to waive Liz's right to a jury trial—found her guilty of first-degree murder. Announcing the verdict, he called the evidence presented at trial "overwhelming" and said the court found "beyond a reasonable doubt that the defendant intentionally killed Cari Farver with deliberate and premeditated malice, on or about November 13, 2012, here in Douglas County, Nebraska."

Liz was sentenced to life in prison without the possibility of parole (plus 20 years for arson) and the now-48-year-old remains incarcerated at the Nebraska Correctional Center for Women, according to online records.

"She obviously does not take responsibility for what happened," Leslie Rule, who unpacked the case in her 2020 book A Tangled Web, told ABC News. Liz had sent her letters from prison, writing, "'I will not stop fighting until I am set free and they find the right person.'"

Jim marveled at the "level of cold-heartedness" that allowed Liz to act as she did when Cari's son Max reached out on Facebook with questions only his mom would know the answer to, in order to see if the person posting in Cari's name was really her. 

"I don't know how that doesn't break anybody's heart, but it didn't affect her one bit," Jim told USA Today ahead of the premiere of Lover, Stalker, Killer. "She didn't care that she was hurting Cari's mom, her child, or anything. Not one bit of remorse."

In the documentary, Nancy credited Jim, Ryan and Tony for no less than saving her sanity.

"They'll always be my boys," she said. "They're fantastic at what they do. If it hadn't been for them, I'd still be in the dark, now."

Liz "ruined my life," Dave told People ahead of the doc's premiere, "as much as you can without actually killing me."

Spending years thinking Cari was out to get him, then finding out she'd been dead all along and that "the person who I leaned on" was responsible for killing her, he said, was "still hard to even process."

Now 47, Dave lives with his girlfriend Margie Hover in Nebraska and doesn't give his phone number or email address out to just anybody. "It's not hard," he said, "to see why I don't trust anybody anymore and keep my walls up."

For more true crime updates on your need-to-know cases, head to Oxygen.com.