What seemed like a horrific stalking case was a jealous lover's cover for murder

"My favorite thing to do is stand outside and stare at you," one message read.

Dave Kroupa watched his cell phone blow up with dozens of text messages from his stalker.

"My favorite thing to do is stand outside and stare at you," one message read.

Kroupa, 36, was almost used to it by now. He would go on to receive tens of thousands of texts and emails like this over a three-year period.

The messages are rife with jealousy and rage at first, then over time, the tone changed from spiteful to threatening.

"I hate you so much that I want to drive a knife in your heart," read one message.

"I will destroy your life and take your happiness," read another.

Kroupa said he can't remember how many times he changed his phone number, and yet, the messages kept coming.

"What do you do when somebody invades every space of your life?" he said.

They all appeared to be from Cari Farver, a woman he dated for only two weeks in Omaha, Nebraska, but no one had physically seen her for a long time.

It was years after the harassment began that detectives uncovered a vindictive lover, who had gone to extreme and deadly lengths to destroy her perceived rival.

Author Leslie Rule was so fascinated by this story that she wrote a book about it called "A Tangled Web." Rule's name might sound familiar, as she is the daughter of legendary true crime writer Ann Rule, who wrote the classic book "The Stranger Beside Me" about her friendship with Ted Bundy.

A brief, chance encounter

Kroupa moved to Omaha in 2012 after taking a job managing an auto repair shop. At the time, he was separated from his longtime girlfriend Amy Flora, with whom he had two children. It was his first time on his own in a while.

"I didn't know how to venture back into the dating pool," he said. "I felt pretty rusty … so internet dating was … the way to go."

Kroupa said he signed up for a couple of dating sites. The first person he met through one of them was a woman named Shanna Elizabeth Golyar, who went by "Liz."

"I thought Liz was very pretty. I was attracted to her right away, so then we set up a date," he said.

Golyar told him that she was a single mother with two kids who were around the same age as his kids. By the fourth date, Kroupa said their relationship escalated and they started having sex. But Kroupa said he was also up front with Golyar, telling her that he wanted to continue seeing other women.

About six months after meeting Golyar, Kroupa said an "extremely attractive woman" walked into the auto shop. It was Cari Farver, a single mom who had brought in her Ford Explorer for maintenance.

"When we looked at each other, there was a little spark," Kroupa said. "She's showing me something inside the vehicle and we're standing there, and we're very close ... and there was some tension."

By all accounts, Farver was vivacious and warm, according to friends and family.

"You noticed Cari when she walked into a room," said her friend Amy Long. "She had a laugh, she had a smile. She lit up a room... You couldn't help but notice her. You were drawn to her."

Kroupa asked Farver out, and said the two immediately hit it off on their first date. So, he invited her back to his apartment after dinner. As things were heating up, Kroupa said Farver told him she didn't want anything serious.

"I felt like I hit the jackpot with that," Kroupa said.

But as she was leaving his apartment at the end of their date, Kroupa said Farver walked right by Golyar in the hallway. Golyar had come by unannounced to pick up some things she said she had left there.

"It was just a brief encounter, maybe 10 seconds or less … but this encounter would go on to have lasting ramifications for all three of them," said Jenn Carpenter, host of the "So Dead" podcast, which followed the case.

Kroupa was so quickly taken with Farver that when she was tasked with a big project at work, he offered to let her stay with him. Farver worked as a computer programmer and her office was located around the corner from where Kroupa lived, he said, whereas she lived nearly an hour away in Macedonia, Iowa.

On the morning of Nov. 13, 2012, Kroupa said he got ready for work, kissed Farver on the way out and told her he would see her later that evening.

Then, around mid-morning, Kroupa said he got a strange text from her saying she wanted to move in together, "which was very left field because we had already talked about that not happening," he said.

Kroupa texted her back saying he wasn't interested. She responded almost immediately, saying, "Fine. I hate you. I'm dating someone else. I don't want to see you anymore. Go away."

"Lots of profanity," Kroupa said. "I didn't know what to think. I was blown away."

When Kroupa returned home that night, Farver was gone. Nearly two days passed before he said his phone started blowing up again with texts, in which Farver said, in part, "I hate you ... you've ruined my life... You're a terrible person."

At the moment, Kroupa said he thought, "I don't need this… I dodged a bullet."

Cari Farver's mother, son receive strange texts

Farver's mother, Nancy Raney, says her daughter was diagnosed with depression in her late 20s -- a few years after having her son, Max Farver -- and that she was eventually diagnosed with bipolar disorder.

"She had been seeing therapists and was on medication," Raney said. "There was a couple of times when she would stop taking the medication because she said, 'Mom ... I feel like I'm numb.'"

But by the time Farver was dating Kroupa in 2012, Raney said her daughter was in a good place, working at her dream job in Omaha, and Max was a thriving high school student.

Around the time Kroupa was receiving those intense text messages, Raney said she too began receiving strange texts. One message claimed Farver had taken a new job in Kansas, which Raney said, "totally threw me."

She tried to get Farver on the phone, but said her daughter wouldn't call back, which was unusual. When Farver didn't show up on her half-brother's wedding day, Raney reported her missing.

Raney said she told the police her daughter was diagnosed with bipolar disorder and that she was on medication.

"The police jumped on that and said, 'Well, this kind of thing happens all the time. When somebody who's bipolar stops taking their meds, sometimes … they can start some really erratic behavior,'" said Rule, who wrote "A Tangled Web" about the case.

Raney said she couldn't get the police to take her pleas seriously.

ABC News reached out to the Pottawattamie County Sheriff's office for a comment on the initial stages of the investigation. In a statement, they said, the department "takes all missing persons reports seriously no matter the circumstances surrounding them."

"The available evidence during the initial investigation was inconclusive, but we did not give up," it added.

Meanwhile, Kroupa said he continued to receive hundreds of harassing text messages and emails from Farver.

"I will do what I can to make you suffer," one message said. Another said, "We belong together, Dave."

He said most of the messages focused on Golyar, the woman Kroupa had previously dated and who crossed paths with Farver in Kroupa's apartment building hallway.

Golyar told him she was also receiving harassing texts and emails. One day, Kroupa said Golyar called him, saying her garage had been vandalized.

"Upon pulling into the garage, she found that someone had written … 'Whore from Dave' on the inside" in spray paint, Kroupa said.

Golyar reported the incident to Omaha Police in late November 2012.

Spotting Cari Farver's car in a parking lot

As the weeks went by, Farver continued to miss more family events, including her own birthday, her son's 15th birthday, Thanksgiving and then her father's funeral.

Raney was convinced something was wrong. She said she was still getting texts from Farver and begged her daughter to call her so she could hear her voice, but she never did. She said Max also started getting messages from her, saying she was going to Kansas and coming to get him, but she never showed up.

Raney said the texts became mean and angry, "saying that I wasn't a good mother and that I was controlling." She noticed that oftentimes the texts would be full of grammatical and punctuation errors, as well as spelling mistakes, which she said was out of character for her daughter, who was "a stickler for punctuation and spelling."

For Kroupa, the harassment wasn't just over text and email, he was also being stalked.

"On one specific occasion, I was sitting in my La-Z-Boy with my feet up, watching TV, trying to relax, and it's nighttime and I get a text saying, 'I see you. You're sitting in your chair with your feet propped up, wearing a blue shirt.' And those things were true," he said.

One night in January 2013, almost two months after the harassment began, Kroupa was returning home from work when he noticed a familiar vehicle in a nearby parking lot. As he got closer, he realized it was Farver's Ford Explorer. Having worked on the car he knew it fairly well, so he said he took a photo of the license plate and sent it to Omaha Police.

When police searched the car, they were able to find only a single fingerprint on a mint container. It didn't match Farver or anyone in the FBI's national database.

Meanwhile, weeks turned into months, and Raney still hadn't found her daughter. One beacon of hope arrived five months after Farver disappeared, when Raney says a man called her to tell her he'd seen Farver at a homeless shelter and that she wanted Raney to pick her up.

"I was shaking… I thought, 'Oh my God, we're going to bring her home, she's going to be OK,'" Raney said.

Raney said she raced over to the shelter and that investigators met her there. But when they arrived, they learned Farver had never been there.

"It was such a letdown and I was just devastated," Raney said. "I get this raising in my hopes and then it's dashed again… I knew somebody was playing games here."

Six months into Farver's disappearance, Max decided to message his mother's Facebook account to see what would happen. She messaged back.

"[It said] 'Hey little man, how are you?'" Carpenter said. "He asked her to answer three questions to prove that it was really her… What his middle name was, what the name of their first [dog] was and what his best friend's name was, and she never responded to that message."

All the while, Kroupa and Golyar, who were still seeing each other on and off, were still receiving hostile, nasty text messages.

"It was actually extremely common for us to be… hanging out on a couch, watching TV or something and both of our phones would start blowing up with text messages and emails from Cari," Kroupa said.

At one point, Kroupa said he got an email from Farver threatening to kill Golyar and that it included a photo of a woman tied up in the trunk of a car. Kroupa called Golyar, who confirmed she was fine. Later, Kroupa said Farver sent him a link to a fake obituary for Golyar.

Then, in August 2013, Golyar's house caught fire, killing her family pets, including two dogs, a cat and a snake. Fire investigators believed it was arson, and Golyar told police she suspected Farver was the culprit.

Kroupa said he had become so paranoid by that point that he bought a gun -- a 9mm Smith and Wesson pistol.

Terrifying intrusions kept happening to him. At one point, the auto shop where Kroupa worked was vandalized. In January 2014, Kroupa was with his high school friend Heather Twedt in his apartment, when Twedt said she watched his cell phone blow up with messages and then later, heard someone jiggering the front door handle. When they were in bed that night, Twedt said a brick was thrown through the window.

Kroupa's ex-girlfriend, Amy Flora, the mother of his two children, had also received threatening messages from Farver.

"It wasn't just Dave and Liz. It was anyone in Dave's life, it seemed, Cari headed out for," Carpenter said.

A new team picks up the case

By spring 2015, it had been two-and-a-half years since anyone had seen Farver, yet the harassment continued.

Detectives Ryan Avis and Jim Doty, of the Pottawattamie County Sheriff's Office in Council Bluffs, Iowa, had never worked on the case but they had heard about it in the office. They were so intrigued by Farver's mysterious disappearance that they volunteered to take it on. The two detectives decided to approach the case from different angles.

"Jim's going to work it like she's dead and I'm going to work it like she's alive. I'm going to try and prove every which way I can that Cari is still out there, and Jim is going to try and prove every which way that she is not," Avis said.

So they started from the beginning, digging through the original case file. The detectives were aware of Farver's bipolar diagnosis, but they didn't think that had anything to do with her disappearance. Avis thought it was alarming that there hadn't been any activity in her checking account the entire time she had been gone.

"It's not normal for adults to just up and leave and literally spend no money. No one's seen them and no one's heard their voice... It just didn't make sense," Avis said. "She had good income, a good house… I had come to the conclusion that I could not prove she was actually alive."

Doty said the glaring detail that stuck out for him was Golyar, who he said had never been involved in Farver's life until she went missing.

"All of a sudden she's this focus of harassment," he said. "Her name was all over all the reports. So to me, there was something with Liz. … She definitely was a person of interest."

The only forms of communication anyone had received from Farver were electronic. So Doty and Avis asked their colleague Anthony Kava, a digital forensics administrator at the Pottawattamie County Sheriff's Office, for help.

Both Kroupa and Golyar had agreed to have the content of their phones downloaded in 2013 for the initial group of investigators. This content was included in the original case file and Kava started connecting the dots.

"We knew these messages don't seem to really be coming from Cari Farver," Kava said. "Cari, or ... the imposter who was pretending to be Cari, sent Dave about 15,000 email messages over a three year span…. It might've been upwards of 25,000 or 50,000 texts in all."

"Whoever was pretending to be Cari … got more and more sophisticated in what they were doing to try to hide their IP address, to try to hide their real identity," he added.

The investigators found a photo of Farver's Ford Explorer in Golyar's phone dump, which included metadata that showed the photo had been taken about a month before police recovered the vehicle.

"Somehow Liz knew where Cari's vehicle was before law enforcement even did," Doty said. "Another thing we found on the phone download was there were six calls that were made to Cari's residence. It was using the *67 prefix to disguise the number, so Liz was calling Cari six times. This didn't make sense to us because she said she'd only met Cari one time passing through a hallway."

The investigators also found the photo of a woman who had been tied up, which had been emailed to Kroupa, and determined it had been taken by Golyar's phone. They also discovered a video recording that showed someone walking outside of Kroupa's apartment. It had been uploaded to YouTube under Farver's name, but was tied to an IP address registered to Golyar's house.

In May 2015, Doty and Avis went to interview Nancy Raney, during which they said they believed her claims that her daughter was missing and that something had happened to her.

"[Doty] said, 'I just want you to know, I don't think she left on her own free will,' and that was the first time anybody of an authority position had told me that," she said. "I honestly felt like something was going to happen now."

During their meeting, Raney provided investigators with another clue. She told them that after Farver disappeared in 2012, she received a text saying Farver had sold all her furniture and asked Raney to let the buyer into the house to pick it all up. As supposed proof of the sale, Raney received a photo of a check for that furniture that was made out to Farver and signed by "Shanna Golyar."

"We knew Liz Golyar's real name was Shanna," Doty said. It was yet another connection between the two women who supposedly were strangers.

"Granted, [that] didn't give us any answers on what had happened to Cari, but we knew [that] Liz knew more than she was telling us."

The investigators also matched the mysterious fingerprint found in Farver's car to Golyar.

As their investigation was underway, Kroupa realized the pistol he had purchased for protection was missing. He reported it stolen to police.

Detectives devise a ruse to ask Liz Golyar for help

On Dec. 4, 2015, Doty and Avis were at the Pottawattamie County Sheriff's Office when Golyar walked in. Stunned to see her, they learned she was there to file a harassment complaint against Kroupa's ex-girlfriend, Amy Flora.

After Golyar left, Avis drove over to her house to interview her, pretending it was about her complaint. She told Avis she now thought it was Flora who had been sending her threatening messages this whole time, not Farver.

The investigator asked if he could download the contents of her phone so they could review the messages. Golyar signed the consent form and turned it over.

Avis said he couldn't believe she agreed to it. Getting access to the information on Golyar's phone was an important moment in the investigation.

During their conversation, Avis said Golyar mentioned she knew Kroupa's gun, which she correctly identified as a 9mm Smith and Wesson, was missing and thought Flora had stolen it.

"She realized that she probably shouldn't know any details about the gun and … then any further questions I asked about the gun, she was very vague," Avis said.

In a bizarre twist, Golyar called 911 the following day, claiming she had been shot in the leg while walking alone at night in Big Lake Park in Council Bluffs. Investigators said Golyar at first claimed she didn't know who the culprit was, and then she later said she thought it was Flora.

"I found it highly suspicious that the day before she felt the need to tell me that Dave Kroupa's gun had been stolen … and less than 24 hours later, she is shot," Avis said. "It was pretty quickly determined that most likely Liz Golyar had shot herself."

Police said that Flora was cleared that same evening.

Meanwhile, Kava got to work sifting through the contents of Golyar's cell phone after the second download. He discovered Golyar had registered "upwards of 20 or 30 fake [email] addresses," all of which had some variation of Farver's name.

Kava also discovered that Golyar was using an app which allowed her to schedule future messages. This explained how she could be with Kroupa and both of their phones would get bombarded with messages.

"She was able to send messages pretending to be Cari, and they would arrive while she was sitting on the couch next to Dave," Kava added. "From Dave's point of view, Liz couldn't have sent it because she was sitting next to him the whole time."

Kava estimated that Golyar must have spent about 40 to 50 hours a week impersonating Farver.

"This seemed to be a full-time occupation for her, trying to stalk people and send them messages," he said.

Doty and Avis brought Golyar in for an interview two weeks after she was shot. At the time, they said Golyar kept pushing them to investigate Flora and had no idea she herself was their main suspect in Farver's disappearance.

Doty and Avis came up with a plan. They were going to tell Golyar they believed her story that Flora had shot her and they wanted Golyar's help to get Flora to incriminate herself. They asked Golyar to reach out to Flora and see if she would tell her anything about what happened to Cari Farver. Of course, the detectives knew Flora had nothing to do with Farver's disappearance or the threatening messages that had been sent for years.

Their plan worked. They said Golyar almost immediately fabricated emails she said were from Flora.

"We started receiving messages … that she said were from Amy [Flora] … where Amy confesses to shooting Liz at Big Lake Park," Doty said.

He and Avis continued to press Golyar to ask "Flora," who they knew to be Golyar, for details about Farver's death. A few days later, Golyar did exactly that.

They said she forwarded an email to them that had supposedly come from Flora, saying she had stabbed Farver "three to four times" and stuffed her body into a garbage bag.

"The details were ... bone chilling because they were graphic," Doty said.

As time went on, the investigators said Golyar grew increasingly upset that they hadn't arrested Flora. Doty explained to her that he needed more information -- information only the killer would know.

Within hours, they said more "confession" emails from "Flora" appeared. The emails included that Farver had been stabbed to death in her own car.

"These emails ... gave us Cari's vehicle as a crime scene," Doty said. "What we wanted to do was go back and look at that vehicle to determine if that crime happened there."

This was the third time police had searched Farver's car, but this time, Doty says they pulled the fabric off the passenger seat. Once uncovered, they found a red stain that was determined to be Farver's blood.

Liz Golyar is arrested for the murder of Cari Farver

Becase the murder most likely took place in Omaha, the Omaha Police Department had to be involved, and cold case homicide detective Dave Schneider joined the investigation.

Det. Schneider brought Golyar in for questioning and confronted her with the evidence Doty, Avis and Kava had gathered so far -- the photos on her cell phone, the IP addresses traced back to her house and the confession emails from "Flora."

Golyar denied knowing anything and claimed she didn't have internet service. But while she was being interrogated, Doty and Avis had gotten a search warrant for her apartment.

Inside, they found some of Farver's possessions including a digital camera and a camcorder, which they believed Golyar had stolen from Farver's home. On the camcorder, they found video of Farver talking about how someone had vandalized her car. It was time stamped two days before she disappeared.

On Dec. 22, 2016, Golyar was arrested and charged with first-degree murder.

Douglas County attorney Brenda Beadle, who prosecuted the case, said, "this was by far the most difficult case I've ever tried."

"Most homicides are dark. This one was … bizarre to the point where it would take some convincing to make somebody believe that it actually happened," she said. "There's no way that someone would let their dog die in a fire that they started. There's no way that someone would shoot themselves in the femur."

Golyar's defense attorney James Martin Davis requested to waive a jury trial in favor of a bench trial, meaning a judge would decide the case.

"Not only was there no body, there was no crime scene, there was no murder weapon… There was no proof that she even died," Martin said. "We waived the jury trial to move it up so I could try this case hopefully before they'd find a body."

Then, a few months before the trial was set to begin in 2017, Kroupa remembered he had a tablet in storage, and turned it over to investigators. On the tablet, Kava discovered a micro SD memory card that also had been in Golyar's phone around the time of the murder. The SD card had thousands of deleted images -- all of which he was able to recover.

"I came to a photo that no one had seen before," Kava said. "I wasn't sure what I was looking at first, but it turned out to be ... a human foot with a tattoo."

The tattoo was of the Chinese symbol for the word "mother." It was the same one Farver had on her foot.

"It was shocking," Kava said. "It made me realize that … Liz Golyar killed Cari Farver and she's taking photos of her body."

At trial, Beadle painted Golyar as a "diabolical" and "cruel" woman who killed Farver and then spent years violently harassing others.

Golyar's defense attorney argued that all of the evidence from the state was circumstantial, that at one point Golyar had been considered a victim in all this and Farver's body hadn't been found.

In 2017, Judge Timothy Burns found Golyar guilty of first-degree murder and sentenced her to life in prison. During his ruling, Burns said, "Cari Farver did not voluntarily disappear and drop off the face of the earth. Very sadly, she was murdered."

In a statement to ABC News, the Omaha Police Department said, "The unusual nature of this case, and the great lengths that Shanna Goylar went to hide this homicide, undoubtedly perplexed everyone involved.

"The successful investigation between the Omaha Police Department and the Potawatomi County Sheriff Office resulted in the successful prosecution of Shanna Goylar and brought to light an extreme level of deception that law enforcement rarely encounters," it continued.

Golyar remains at the Nebraska Correctional Center for Women. To this day, she maintains her innocence and claims Farver's real killer is still out there.

Author Leslie Rule said she received letters from Golyar while she was behind bars, one of which said, "I will not stop fighting until I am set free and they find the right person." "She obviously does not take responsibility for what happened," Rule said.

"I want Liz to go away and never do this to anybody again," Kroupa said. "Nancy and Cari's son were foremost … in my mind … They're, unfortunately, the ones that have to live with the repercussions."

Kroupa added that the investigators who solved the case, "Doty, Avis, Kava, they're all heroes."

"Those guys, they mean the world to me. I can't thank them enough. They're my boys," Nancy Raney said.

The three investigators established a scholarship fund in Farver's name at the local community college she had attended in hopes of associating "something positive with her memory," Kava said.

When asked how she wanted her daughter to be remembered, Raney said "as the fun-loving, talented, smart woman that she was."

"Cari was only 37 when she died," Raney said. "If I could talk to CarI right now, I'd say 'I love you. I'm so glad that you are in my life. You have a beautiful son who's got a wonderful life coming, and I miss you terribly.'"