Low IQ raises doubts over murder intent in Seoul drugging case

Kim So-young, 20, accused of causing the deaths of two men at a motel, appears at the Seoul Northern District Court, Feb. 12, to attend a warrant review hearing. Yonhap

A Korean woman accused of giving men drug-laced drinks that left two dead told police she never meant to kill anyone, but investigators say her phone records contradict that claim.

Police found ChatGPT queries in which Kim So-young asked what happens if someone takes too many sleeping pills and whether a person could die after taking them. Officers say those searches, along with evidence that she later gave a victim more than twice the dose she used in an earlier nonfatal case, support a murder charge because she could foresee the risk of death and proceeded regardless.

Prosecutors charged Kim, 20, with murder and aggravated injury, then added a charge under the Narcotics Control Act, while her lawyer says she gave the men the drugs but had no intent to kill and could not foresee the deaths.

The case now hinges on a central question in Korean criminal law. Did Kim intend to kill, or did she give the drugs to incapacitate the men while disregarding an obvious risk that they could die?

Suspect identification

Police first began to build the case after a man was found dead Jan. 29 at a motel in Suyu-dong in Seoul’s Gangbuk District. Investigators tracked the woman who entered the room with him through dashcam and security cameras, identifying her as Kim So-young on Feb. 6.

When officers searched Kim’s name in the criminal database, they found another case that raised immediate alarms.

A man in his 20s filed an aggravated injury complaint against her after he lost consciousness in December. The case document said the survivor told police that Kim, who dated him at the time, handed him what she called an energy drink in the parking lot of a bakery cafe in Namyangju on Dec. 14 and told him, “You must have been tired driving.”

About 20 minutes later, he collapsed inside the cafe. Doctors diagnosed him with toxic encephalopathy, and he remained unconscious for two days. After he recovered, he pressed Kim about what she gave him, but the log said he “did not hear a proper answer.” He later filed a complaint and submitted hospital records showing benzodiazepines in his system.

That earlier case prompted police to revisit the death in Suyu-dong. They asked the National Forensic Service whether it found benzodiazepines in the victim’s body. The service told police Feb. 9 that it found the same class of drugs.

Officers moved to search Kim’s home the next morning. Before they could execute that search, another man was dead.

At about 8:30 p.m. on Feb. 9, Kim entered a room at another motel in Suyu-dong with another man in his 20s. About two hours later, she left abruptly carrying three black bags filled with 22 items from a fried chicken restaurant. The food cost about 130,000 won ($88).

Kim So-young, a suspect in the Gangbuk motel drug deaths, ordered 22 items from a nearby chicken restaurant on the day of the second fatal poisoning. Courtesy of the restaurant owner

A motel employee opened the room the next day after the guests failed to check out by late afternoon and found the man lying alone on the bed.

“He’s not breathing and his body is stiff. Secretions are coming out of his nose and other places,” the worker told emergency responders.

Police reviewed the motel’s surveillance footage and immediately recognized the woman who went in with the victim. She was the suspect whose home they had already targeted in the earlier case.

Officers arrested Kim outside her home in Gangbuk within hours. During the search, they seized a large quantity of psychotropic drugs, empty hangover cure beverage bottles that investigators said she used in the crimes and her cellphone.

The toxicology report confirmed both victims died of drug intoxication. Investigators said Kim used the butt of a kitchen knife to crush prescribed pills into powder and mixed the powder into drinks she gave to the victims. The drinks contained benzodiazepine-class psychotropic medications, including Lunapam and Samjin Diazepam, which Kim obtained through psychiatric treatment.

Kim So-young, right, a suspect in the Gangbuk motel drug deaths / Courtesy of an acquaintance of Kim

Kim denied she meant to kill the men. She told police she had "no intention" of killing them. She said after arguments arose inside the accommodations, she gave the men hangover cures mixed with medicine because she wanted “to make them fall asleep.”

She appeared shocked when officers told her the two died.

“I did not know they could die because they were antidepressants I had been taking,” she said.

ChatGPT searches and dosage escalation

Investigators say the strongest evidence against that account came from the phone they seized at her home. Digital forensics uncovered chat logs with ChatGPT.

Three days before the first killing, Kim asked the chatbot, “What happens if you take a lot of sleeping pills?” It replied that if someone took them with alcohol, “the risk of death from respiratory paralysis is very high, so an immediate 119 report is required.”

On the day of the murder, she asked again, “Will a person die if they take a lot of sleeping pills?” The chatbot answered, “That is possible.”

Police also found Kim used more than twice the amount of drugs in the fatal case involving the second victim than she used in the earlier case involving the survivor.

Based on the cases, police concluded Kim was grossly negligent in using drugs capable of endangering life, not merely inducing sleep. They handed her over to prosecutors Feb. 18 on murder and aggravated injury charges.

The OpenAI logo is displayed on a mobile phone in front of a computer screen with output from ChatGPT. AP-Yonhap

Prosecutors later added a charge under the Narcotics Control Act and indicted Kim while she remained in custody March 10. Prosecutors said she sought psychiatric treatment beginning in August 2025 for post-traumatic stress disorder she did not in fact have, so she could obtain the drugs.

Prosecutors believed she initially pursued that false diagnosis so she could support a criminal complaint against a man who reported her for theft.

Emergence of additional victims

The investigation continued after prosecutors took the case. Police conducted a full review of men who had contact with Kim and found three additional alleged victims.

One man lost consciousness after drinking wine with her at a restaurant in Bangbae-dong in Seoul’s Seocho District on Oct. 25, 2025. Another man in his 20s lost consciousness in a motel room in Jongno in early January 2026. A third man in his 30s collapsed at a karaoke bar in Suyu-dong Jan. 24. Kim called 119 and said the man “won’t wake up after drinking.”

All three survived. One no longer had detectable drugs in his system because time passed, but hair analysis found benzodiazepines in two of them. Police sent Kim to prosecutors again March 19 on additional aggravated injury and drug-law charges.

Debate over suspect privacy

The case drew controversy over revealing Kim’s identity. Police considered disclosure before sending the case to prosecutors but decided against it, saying the crime did not meet the threshold for disclosure of personal information of suspects in serious crimes.

The law requires authorities to weigh whether the crime involved cruel means and grave harm, whether evidence is strong and whether disclosure serves the public interest, including the public’s right to know and the need to prevent repeat crimes.

Victims’ families pushed back. They filed a petition with the Seoul Northern District Prosecutors’ Office urging officials to reconsider.

Online users began tracking down Kim’s social media and circulating unblurred images of her face. Her Instagram account jumped to more than 11,000 followers in 10 days.

On March 9, after a review by an identity-disclosure committee, prosecutors posted her mug shot, name and age on the office website for 30 days. That decision came 19 days after police transferred the case.

The Seoul Northern District Prosecutors’ Office releases the identity of Kim So-young, March 9. Kim is accused of fatally drugging men in their 20s and 30s at motels in northern Seoul. Courtesy of Seoul Northern District Prosecutors’ Office

Psychopathy claim and IQ question

Kim’s first trial opened Thursday at Seoul Northern District Court. Wearing a green detention uniform and a white mask, she stared blankly throughout the hearing.

“The defendant admits that she gave the drugs,” but “only meant to make the victims fall asleep, had no intention of aggravated injury or murder” and could not have foreseen the deaths, her court-appointed lawyer said.

Prosecutors responded that the case involved “repeatedly administering psychotropic drugs exceeding the lethal dose” and killing two victims.

Even with the trial underway, Kim’s motive remained blurry. Early in the investigation, police treated the case as a planned crime with an abnormal motive.

A police-administered Hare Psychopathy Checklist-Revised test gave Kim a score of 25 out of 40, which meets the threshold for qualifying a person as psychopathic in Korea. Prosecutors also described her in the indictment as lacking guilt and empathy, acting in a self-centered way and struggling with emotional control in unstable relationships.

A question over Kim's capacity to commit murder, however, was raised after a criminal psychologist revealed her intelligence assessment conducted by experts.

Lee Soo-jung, a criminal psychology professor at Kyonggi University, discusses the low intelligence of suspect Kim So-young during an appearance on the Chosun Ilbo’s YouTube channel. Captured from Chosun Ilbo’s YouTube

Lee Soo-jung, a professor at Kyonggi University, said on Chosun Ilbo’s YouTube channel that Kim's IQ fell between 70 and 80, just above Korea's borderline for intellectual disability.

“Kim fell in the bottom 10 percent of the population and outside the standard range of 85 to 115,” the professor said. “If intelligence is markedly low, it is difficult to carry out meticulous, planned behavior.”

Question of intent

Kim’s actions during and after the crimes raised further questions over how much planning the case involved.

After giving the second victim a drugged drink, she used his card to order 22 fried chicken menu items worth 130,000 won to the motel, then left about 10 minutes after the food arrived. She later sent him a long text message that included the line, “Thanks for the taxi fare.”

During the search of her home, Kim told police she “gathered the empty bottles used in the crime,” effectively helping officers collect evidence.

Although investigators said Kim proposed motel stays in both fatal cases, a prison letter later quoted her as saying, “I made them sleep because I was afraid of sexual assault.”

Before the first hearing, a victim's family submitted 94 petitions urging the court to impose the death penalty. The family also filed a civil suit seeking 31 million won in damages from Kim and 1 million won from her parents.

The Seoul Northern District Prosecutors’ Office in Dobong District, northern Seoul / Korea Times file

The next hearing is scheduled for May 7.

The court now must decide whether Kim’s repeated use of prescription sedatives amounted to murder even without a confession that she meant to kill.

Prosecutors say the dosage, the prior nonfatal case and the chatbot warnings show she understood the danger. But the defense says she only meant to render the men unconscious.

That dispute now sits at the center of one of Korea’s most closely watched criminal cases.

This article from the Hankook Ilbo, the sister publication of The Korea Times, is translated by a generative AI system and edited by The Korea Times.