True Crime (6) Marrying to kill

A marriage is meant to be the ultimate expression of love, a sacred vow between two people, blessed and celebrated by family and friends. A promise of loyalty, trust and lifelong partnership.

But what if that bond is tainted from the very beginning? What happens when one walks down the aisle with love in their heart, while the other sees only images of money?

Such was the marriage of Lee Eun-hae and Yoon Sang-yeop.

In this episode, we dive into a 2019 case known as the Gapyeong valley murder, where the husband drowned during what was supposed to be an early-summer getaway with acquaintances. It wasn’t an accident. It was a planned killing orchestrated by his wife and her secret lover.

This is a story of gaslighting and one-sided love, where a man’s only sin was loving someone without knowing her true colors.

Yoon's death occurred in 2019, but it was not until the following year that the authorities launched a full-on murder investigation. And ironically, it was the wife who helped trigger it.

In March 2020, Lee reached out to producers of the SBS investigative program "Unanswered Questions." Locked in a dispute with an insurance company, she was frustrated that she had not received the payout from her husband’s life insurance policies. Claiming he had died in a tragic drowning accident during a trip with friends, she hoped media pressure would force the company to release the funds.

The tragic day was June 30, 2019. Yoon, then 39 years old, joined his wife Lee, 28, along with Cho Hyun-soo and several of the wife’s friends on a trip to a valley in Gapyeong, Gyeonggi Province. That day, Yoon drowned. The initial police investigation ruled it an accident.

But Yoon’s older sister could not accept that explanation. She filed a formal complaint with the police, asking that they reexamine the case for potential foul play.

In November 2019, about five months after Yoon’s drowning, the police decided to reopen the case. A major red flag was that the victim had been signed up for multiple life insurance policies — all listing his wife as the sole beneficiary.

As police reinvestigated, the insurance company refused to release the payout, prompting Lee to turn to the media for help.

The SBS show aired in October 2020, but not in a way she had hoped: It shed light on suspicious circumstances surrounding Yoon's death and the bizarre dynamics of his marriage to Lee, as well as the questionable involvement of Cho, her male companion on the fatal valley trip, who appeared to be much more than just a family friend.

There is no doubt that Yoon died by drowning, and he himself jumped into the deep water. But there was one major issue: He didn’t know how to swim, and video evidence suggested he never wanted to.

Footage taken by Lee Eun-hae herself showed Yoon lingering in the shallows, floating on a pool tube. In the video, a few men — Lee’s friends — are seen teasing and dragging him toward deeper water, while Lee laughs and encourages them. At one point, the men try to flip the flotation device, and Lee can be heard saying, “He can’t. (The tube) is too heavy. Hey, (name), go flip it with him.”

Yoon repeatedly tells them to stop, but they do not.

The video stopped well before the fatal dive, and experts said the clips appear to have been edited.

According to testimony from a woman surnamed Choi, the girlfriend of one of the men on the trip, Lee encouraged Yoon to dive into the water, saying, “All the men are diving.” When Yoon refused, Lee said she would dive in instead.

Notably, Yoon had been wearing a life jacket earlier, but no longer was by the time he entered the deep water.

Lee claimed during the investigation that after Yoon jumped into the water, no one saw him struggle or heard any cries for help. But Choi gave a different account — she testified that she heard splashing and the sounds of someone struggling. It was past 8 p.m., and the valley was already dark.

She saw Cho, the suspicious man mentioned earlier, swimming toward Yoon. But in the next critical minutes, she was not at the scene to witness what happened because Lee had asked her to help fetch the flotation device.

This woman also recalled other troubling details about the trip. Lee had introduced the victim to others as just a “close friend,” and she never suspected them to be married because Lee was openly affectionate with Cho.

It was later revealed that Cho was Lee’s longtime boyfriend. Choi’s partner at the time, who had brought her along on the trip, was also a mutual friend of Cho and Lee with a criminal past. Choi's boyfriend was later sentenced to five years in prison for acting as an accomplice to Lee and Cho.

What the victim thought to be a getaway with his wife and her friends was, in reality, a plan for his death — a trap laid by the wife and aided by an extramarital lover and another acquaintance of ill repute, both present at the scene.

The valley incident was not the first attempt on Yoon’s life. Police confirmed that Lee and Cho had conspired to kill Yoon on at least two previous occasions.

In May 2019, Cho invited Lee and Yoon to accompany him and his purported girlfriend on a fishing trip in Yongin, Gyeonggi Province.

Cho's girlfriend later revealed that on that trip, Lee had also forced Yoon to go into the water despite his protests. She said she heard someone fall into the water at night, after which Lee came in and told her, "Nothing happened, just lie down."

The woman went outside anyway and saw Yoon tell Lee, "You pushed me in. I know that," followed by the couple getting into a fight.

Another attempt at Yoon's life was confirmed by the police investigation, which was revealed via a recovered messenger conversation between Lee and Cho. In the conversation that took place on Feb. 17, 2019, Lee complained about there not being enough poison in the blowfish she had fed Yoon, to which Cho answered, "I heard you can die by (blowfish) blood or other stuff."

"I fed him so much, why is he still alive?" Lee asked.

Lee and Yoon started dating in 2013 and wed in 2017. It was Yoon's first exchange of vows, but Lee's third marriage and fourth engagement.

Born in 1991 to a poor couple with disabilities, Lee had multiple run-ins with the law involving prostitution and theft even before she was legally an adult. Her first arrest was in 2006, when she was just 15 years old, for receiving 160,000 won ($113 today) from an adult in exchange for sex.

Lee had actually appeared as a child in March 2002 on an MBC TV show about remodeling homes for impoverished families. Comedian Shin Dong-yeob, the host at the time, said he had been impressed at how such a young child could take care of her family and expressed shock at how she turned out.

As a minor, Lee was tried five times in juvenile courts, mostly for stealing from men whom she lured to motels on the pretense of having sex with them. Records indicate instances of prostitution and petty theft before her pregnancy at the age of 19 in 2010.

Her first husband died sometime in 2010 in a car accident. Lee was not the focus of any suspicions or subject to any criminal charges involving the death.

Lee's second relationship on record was with a man with whom she was in a common-law marriage. They went on a trip to Pattaya, Thailand, in July 2014, where he drowned in a snorkeling accident. As in the death of her first husband, forensic evidence did not apparently suggest any wrongdoing.

The older brother of the second husband said that the cellphone of the deceased had disappeared, and that he felt Lee's story did not match the actual details of the accident. The payout from the man's insurance was given to the victim's family, not Lee.

A police reinvestigation of the Pattaya case did not find any indications of criminal intent, and it was closed in 2022.

In 2016, Lee married again in a ceremony in Incheon. Before the wedding, she refused to introduce her family to the groom or his relatives, claiming they were busy. The groom’s family later moved to cancel the nuptials after discovering that the bride’s family and guests were all hired actors.

That wedding ceremony took place while Lee was already romantically involved with Yoon. One year after the Incheon wedding fell through, Lee married Yoon and enrolled in multiple life insurance programs listing herself as the beneficiary.

As Lee’s murder came to light, the public was left asking: “Why?” Why would a grown man, fully capable of making his own decisions, be coerced into taking a fatal dive?

Yoon had been reluctant to enter the water, wearing a life jacket and refusing to go into the deep end on the day of his death. Yet conversations between him and Lee suggest he had been subjected to psychological manipulation, or gaslighting.

Records show that Yoon was subject to physical and verbal assault from Lee, although it remains unclear if he was aware or not of Lee's multiple affairs. In a recorded conversation with Yoon, Lee claimed she tends to mistreat people whom she feels close to when drunk.

Phone conversations between the two revealed by media show Lee controlling aspects of Yoon's life, becoming infuriated when he told her someone wanted to make a house call, even as Yoon assured her that he had said no. Although Yoon and his family paid for a home in Incheon, he lived alone in a semibasement in Suwon, apart from his newlywed wife. His friends wondered why he had to live separately, especially since Lee did not have a job at the time.

It was only after Yoon's death that the family learned he had adopted Lee's daughter from her first marriage, and that he had lied about Lee being an intern at his company.

Yoon was alone for both Christmas 2018 and the following New Year's Day. Two days before Christmas, Yoon called Lee and suggested that they break up, and when Lee confronted him for wanting to part ways, he said, "No, it's not because you hit me yesterday. I just don't have money. I'm too broke. I have so much debt."

Yoon, a graduate of one of Seoul’s top universities, had reportedly accumulated at least 300 million won ($204,568) in personal assets before marriage. He was earning 64 million won annually as a biomolecular engineer at a major company. In 2018, just about a year after marrying Lee, he filed for debt rehabilitation with 135 million won in debt — around the same time he told Lee he was considering divorce.

A KakaoTalk conversation with an illegal organ broker also shows that he tried to sell a kidney around this time. Another conversation between Yoon and Lee on Dec. 21, 2018, showed her asking for 2 million won right away for a trip and getting mad when he said he had used the money to pay for rent.

"I told you not to pay the rent," she said.

In a phone conversation on Dec. 29, 2018, Lee told Yoon that she was with Cho. When Yoon said he only had 110,000 won, she said, "OK. I'm hanging up."

Yoon sent a message to himself before his death, which showed that he was exhausted and had bought a rope to hang himself: "I feel sorry for (wife Lee) Eun-hae, but honestly, she won't even notice that I'm not there. ... I don't think she'll be there at my funeral. She's always busy."

"I have to die for the insurance payout. I hope Eun-hae knows this to get the money," he wrote. "It's sort of nice telling myself something that I can't tell anyone."

Around the time Yoon filed for debt rehabilitation in June 2018, he asked Lee for 30,000 won to cover his meal expenses. In another text, he told Cho that he mistakenly sent 9,624 won, and asked him to wire just 7,000 won back, saying he was too hungry because he had not eaten.

Two days before his death, Yoon asked a friend for just 3,000 won to buy ramyeon and a bottle of water. The friend wired 100,000 won and said, "You don't have to pay me back," but Yoon sent back 97,000 won anyway.

Over the span of two years, Yoon spent all his cash, money lent by family and acquaintances, and loans from his company and banks. He primarily wired the funds to Lee, her family and her friends. Lee's mother later told the media that she never received the money Yoon supposedly had sent her.

Criminologist Lee Soo-jung said in a court-submitted consultation that Lee tested well above the threshold considered for a diagnosis of psychopathy. She said Lee also showed signs of narcissism and that she had formed a relationship of extortion with the victim.

"I have no choice but to say that the victim was psychologically dominated and manipulated by Lee. He could have reached out to his older sister or to police for help, but he was in a state of panic that disabled him from considering any other possibilities," the criminologist said in court.

The prosecution accused Lee Eun-hae and her accomplices of coercing the victim to jump into deep waters without safety gear and not undertaking actions to rescue him, thereby constituting murder via omission. She was found guilty of murder and insurance fraud, with the verdict confirmed by the Supreme Court in 2023. She was sentenced to life in prison.

Cho, Lee's lover and the main accomplice in the murder, was sentenced to 30 years in prison. He also had a prior criminal record.

Lee's marriage to Yoon was nullified by the Incheon Family Court in 2023, as the court ruled that Lee had no intention of actually being in a marital relationship and had only attempted to extort the victim. She also lost her lawsuit against the insurance company to receive a payout from Yoon's death in 2023 and did not appeal the ruling.

Lee and Cho remain in prison, along with Lee's other accomplice, who received a five-year term in 2024.

This article is a written adaptation of The Korea Herald's podcast True Crime. You can listen to the full episode on Spotify and Podbbang. ― Ed.