On the night of October 29, 2011, there was Halloween excitement in the small town of Dyersburg, Tennessee. This spirit became truly dark when Karen Swift, a 44-year-old mother of four, disappeared. Only her car, found abandoned on a country road by two hunters the next morning, and her two broken cell phones, discovered near a neighbor's house, remained.

Six weeks later, what began as a missing-person case became a murder mystery when Karen's body was found hidden under a tangle of vines by a caretaker near Bledsoe Cemetery in Dyer County. An autopsy revealed she had suffered blunt force trauma to the head.

The case was shut down and no arrests were made for over a decade, leaving a shadow over Halloween in Dyersburg and haunting the community. On August 8, 2022, the cold case thawed when police announced the arrest of Karen's husband, David Swift. After David was indicted by a grand jury, he was charged with first-degree premeditated murder. He pleaded not guilty to the charge.

Watch the “20/20” episode “Her Last Halloween” airing Friday, November 1st at 9pm on ABC and streaming on Hulu beginning November 2nd.

The arrest came as a shock to many, including David and Karen's then 20-year-old daughter Ashley.

“I remember trying to figure out why,” Ashley Swift said in a new interview with “20/20.” “Why now? Why is this happening after all these years?”

David's trial began on May 28, 2024. Community members wondered what evidence would explain his sudden arrest after eleven quiet years.

On the first day of the trial, the prosecution warned jurors that they would not present this as a DNA case and that their key evidence would not be fingerprint or ballistics tests.

District Attorney Danny Goodman instead painted a portrait of a troubled marriage when Karen filed for divorce three weeks before her disappearance. The two have separated in the past and even divorced in 2000 before remarrying that same year. But prosecutors suggested this time would be more definitive.

On the morning of October 29, 2011, the eve of the evening Karen disappeared, she rejected David's conciliatory offer to have dinner with him later that evening. The state's theory was that the rejection was “consuming” David, as Assistant District Attorney Tim Boxx put it during the trial, and Boxx speculated that David was beginning to understand that Karen was really leaving him, “and this time for good.” .”

Daniel Taylor, David's defense attorney, argued that David's attempts to reconcile with Karen should not be taken as an indication that he felt rejected, but rather as evidence of his hope for a rekindled relationship.

“Did David think they might be able to do it again like they did the first time?” Taylor asked during David's trial. “Did he have hope? Yes.”

Prosecutors also alleged that David attempted to control and monitor his wife's movements in the later days of their marriage.

In response, the defense struggled to convince the jury that David's alleged actions did not exist in a vacuum.

Karen's friends and family claimed that Karen had adopted some sort of new identity in the period leading up to her murder. She joined a new circle of friends who frequently attended parties at Farms Golf Club in Dyersburg. She also reportedly started drinking and going out more.

“Karen’s behavior has changed with this new group,” David’s girlfriend Kim Greene told “20/20” in an exclusive interview. “She was determined to be out there having fun with them instead of staying home with the kids where she belonged… (David) just wanted to get out to see where his wife was.”

Taylor also questioned the prosecution's premise that David had “control” over his wife. Taylor pointed out that she had access to their joint bank account and that Karen could go wherever she wanted. He also emphasized that David checked on Karen frequently “and it got on her nerves,” but there was no violence involved.

David echoed this sentiment in his interview with “20/20.”

“I have never raised my hand against anyone, now or ever,” David told ABC News' Juju Chang. “And there's no way I would do it to my wife or the mother of my children… It's just not my character.”

Ultimately, David's trial ended on June 6 with an acquittal of first-degree premeditated murder and second-degree murder. However, jurors were unable to reach a verdict on the lesser offense of voluntary manslaughter – a deadlock that led to a mistrial on that charge.

The jury was denied a hearing on the stalking allegations David is facing in Jefferson County, Alabama, involving his ex-wife, Kelly Essman. He met Essman through the dating website Christian Mingle in 2014, three years after Karen's death, and the two married in May 2016.

Essman, who has not shared her story publicly, spoke to 20/20 in an exclusive interview.

“I see how easily I talked to (David) and believed everything he told me,” Essman said. “And the feeling I had that he was serious. Why didn't I see it? How can I trust that I can see through everything else?”

“20/20” captured footage in the middle of the night, after they had already separated, that appears to show David in Essman's apartment.

“I pulled up the feed,” Essman told “20/20.” “And there he was in my backyard in the middle of the night… He had to drive 40 minutes one way to get to my house.”

David was charged with stalking in Alabama in July 2023 and has not yet entered a plea. His attorney did not respond to a 20/20 request for comment on the case.

Despite the allegations against him, David's friends and family said they saw a gentle person.

“David is too kind a person,” Kim Greene said of her friend. “He wouldn’t harm anyone.”

Ashley Swift also recalled her father's compassionate moments, speaking to “20/20” about a time she saw him helping a mother pay for her groceries during the holidays.

“She put things back when she checked out,” Ashley remembers. “And my dad ended up covering everything so her kids could have a nice Christmas. Things like that really stand out to me.”

On October 15, the Tennessee Court of Appeals rejected a request from David's defense to dismiss the case related to Karen's murder, paving the way for a new trial on involuntary manslaughter charges. He pleaded not guilty to the charge.

When Karen Swift first went missing in 2011, the Dyersburg community was gripped by a deep hunger for answers – answers that could provide closure for her and justice for Karen.

After 13 years and one test, this longing remains unfulfilled. But Karen's memory – and the hope of those who cherish her – still promises to endure.

“At the end of the day, I know the truth about my family,” her daughter Ashley told “20/20.” “And I know my mother wants me to keep fighting for her.”