Kang Yun-seong was 56 when he killed two women in the Songpa District of southern Seoul in the last week of August 2021. He had left prison in May of that year after serving a long sentence for a sex offense, and a court had ordered him to wear an electronic monitoring device for five years as a repeat offender. The first woman died on the evening of August 26. On the afternoon of August 27 he removed the device and left. In the early hours of August 29 a second woman died, and that morning he walked into Songpa Police Station and turned himself in.
Both women were acquaintances, and both killings were tied to money. In May 2022 a jury trial at the Seoul Eastern District Court found him guilty on seven counts, including murder and robbery-murder, and sentenced him to life imprisonment. Prosecutors had asked for the death penalty. The Seoul High Court upheld the life sentence in September 2022. The case also became a test of South Korea's electronic monitoring system, which the Justice Ministry had described as a success only weeks earlier, and it opened a debate that reached the National Assembly.
His name is romanized in several ways in English-language coverage: Kang Yun-seong in the Korea JoongAng Daily, Kang Yoon-seong in the Korea Times and Kang Yun-sung or Kang Yoon-sung in Korean outlets writing in English.
The Justice Ministry told reporters that Kang had 14 criminal convictions. Korean press accounts counted eight prison terms among them, beginning when he was 17. Segye Ilbo, in its report on the verdict, dated the first of these to August 1982 and named the offense as special theft; The Seoul Shinmun gave the same offense. The Korea JoongAng Daily described that first term as one for robbery. The two descriptions differ.
His first conviction for a sex offense came in 1996. Segye Ilbo reported a sentence of five years in October of that year for a robbery-rape offense, and CBS Nocut News, which described the offense as assault, robbery and rape, added that the court also ordered protective custody, a form of detention that could follow a prison term for offenders judged likely to reoffend. The Korea JoongAng Daily recorded the 1996 case as his first sex crime.
His second came in 2005. He committed it five months after being released from prison, according to the Justice Ministry, and was sentenced to 15 years. The Korea JoongAng Daily gave 2006 as the year of that sentence; Segye Ilbo placed the case in 2005. Press accounts of the verdict named the offense as special forcible indecency.
Protective custody is central to how Kang's later release is understood. South Korea abolished the system in 2005 along with the Social Protection Act that created it, but sentences already imposed continued to be enforced under transitional rules. CBS Nocut News reported that after his 15-year term Kang was held in protective custody at Cheonan Prison beginning in October 2020. In November 2020, the same report says, he was among 17 detainees there who staged an 11-day hunger strike, and he took part in a meeting with Justice Ministry staff on the matter. The detainees' demands included separate facilities for provisional release, job training and a minimum-wage guarantee. Seoul Shinmun gave the total time he had spent in custody over his life as 27 years.
Kang left Cheonan Prison on May 6, 2021, the CBS Nocut report and the Korea JoongAng Daily agree. Segye Ilbo described the release as an early one, on parole; the Korea JoongAng Daily wrote that he had completed his 15-year term in May. Under the electronic monitoring law he was ordered to wear a location-tracking device for five years.
He was not placed under the closest tier of supervision. The Justice Ministry told reporters that a dedicated probation officer is assigned only to released prisoners with more than three convictions for sexual crimes, and that his record fell below that threshold. His 2005 conviction had also come before the 2008 creation of the public sex offender database, and a ministry official said he was not a subject of that system. The Justice Ministry had nonetheless assessed him as a high risk of reoffending. CBS Nocut News reported that police were not given that assessment at the time the device was removed.
In the months after his release Kang told police he earned income selling cosmetics door to door, mostly to women. Seoul Shinmun reported that police considered this unconnected to the crimes. He met both of the women he later killed after leaving prison, police said, and bank records confirmed money transfers between him and each of them. He appeared to have been living on borrowed money. YTN, reporting on the indictment, wrote that he lived on loans and spent heavily on nightlife.
The first victim was a woman in her 40s whom Kang knew. Prosecutors and the courts established that he needed money that week. He owed a woman in her 50s, the second victim, about 22 million won, and she had been pressing him to repay it. The first woman had refused him a loan. The Seoul Eastern District Court heard that he killed her on the evening of August 26, in Songpa District.
Police judged the killing premeditated, citing preparations he had made beforehand, and prosecutors charged it as robbery-murder because it was committed to obtain money. Kang later disputed this. At his first court hearing in October 2021 he told the judges that news reports had called the killings planned, and he said his candor with the women had been turned into a charge of premeditation. At trial his defense argued that both killings had been impulsive. The jury saw it differently for the first killing.
Her name is not on record.
The monitoring system recorded two alarms on August 27. The first came at 12:14 a.m. and signaled a curfew violation, the Korea JoongAng Daily reported. By 12:34 a.m., before a two-person probation team reached his address, he was back home. It was his third curfew violation since his release. The probation office told him by phone to report for questioning but did not send anyone to see him in person, Seoul Shinmun reported.
At 5:31 p.m. the same day Kang removed the device and left. The removal triggered a second alarm. The Justice Ministry and police began a manhunt that did not find him before he surrendered. Seoul Shinmun reported that the special judicial police attached to probation offices, who had gained the power to investigate tampering with monitoring devices only in June 2021, reached the prosecutors' duty room more than six hours after the removal and were told to come back the next day. An arrest warrant request was filed about 15.5 hours after he fled. Prosecutors told the newspaper that they had not been told of his recidivism risk and had not seen urgency.
Police told reporters they had been given little room to act. Seoul Metropolitan Police Agency Commissioner Choi Gwan-ho said the officers who first responded had not been proactive enough, and he and others pointed out that the Criminal Procedure Act allows warrantless entry to a residence only in narrow urgent cases. Police also acknowledged that the second killing might have been prevented if they had treated the alarm as a murder inquiry rather than a case of a monitored offender absconding. The Korea Times editorial of September 1 made the same point in sharper language.
The second victim was the woman in her 50s who had lent Kang the money. After the device was removed he met her, and in the early hours of August 29 he killed her in Songpa District. Prosecutors put the time at about 3:30 a.m.; Segye Ilbo gave it as about 3 a.m. The motive recorded by police and by the court was the debt: she had demanded repayment of the full amount and, according to Kang, said she would report him to police. The Korea JoongAng Daily's report of September 7, based on a police briefing, placed this killing on August 27, while the indictment and the court gave August 29.
At about 8 a.m. on August 29, roughly 39 hours after he removed the device, Kang turned himself in at Songpa Police Station. He told police he had done so because he believed they would soon catch him. Police arrested him on suspicion of murder, and in the following days he was held at the station.
Police named Kang on September 2, 2021. An expert panel of the Seoul Metropolitan Police Agency, with three police officers and four outside members, met that afternoon and decided to release his name, age and photograph under a special law on serious crimes that allows disclosure when it serves the public interest. He was the seventh suspect whose identity police had made public that year, the Korea JoongAng Daily noted. He had refused to be represented by a lawyer.
The Seoul Eastern District Court granted a detention warrant on August 31. At that hearing, Seoul Shinmun reported, he said he regretted not having killed more people, a remark that provoked public anger. On September 5 he was involved in a disturbance in the Songpa Police Station holding cell, which later became the basis of a count of obstruction of official duties.
Police sent him to the Seoul Eastern District Prosecutors' Office on September 7 on six charges: murder, robbery-murder, preparation for murder, fraud, violation of the Specialized Credit Finance Business Act and violation of the law on electronic monitoring devices. Before reporters that day he said he apologized to the victims and their families, and he said he had killed for money and not for sexual reasons. The Korea JoongAng Daily reported that his account of his motive had shifted during questioning.
Police said they had checked the bank records and found money transfers between Kang and both victims. Investigators found no sign of a sexual offense against either woman, Seoul Shinmun and the Korea JoongAng Daily reported. Prosecutors declined to bring a charge of preparing to kill a third woman, finding the evidence insufficient.
Prosecutors had Kang assessed by the Supreme Prosecutors' Office. Its integrated psychological analysis concluded that he had antisocial personality disorder with psychopathic traits, YTN reported. Segye Ilbo added that a police assessment using the Psychopathy Checklist, Revised, gave him a score above 30 out of 40, where a score of 25 or more is classed as high risk.
The Seoul Eastern District Prosecutors' Office indicted Kang on September 24, 2021, while he remained in custody. The Korea Times counted seven charges. YTN named the main ones: robbery-murder, fraud tied to a mobile phone line he had opened in July, violation of the electronic monitoring law over the removal of the device, and obstruction of official duties for the holding-cell disturbance on September 5. Prosecutors treated the first killing as a planned murder carried out to obtain money, and they did not bring the preparation-to-kill count concerning a third woman.
The Seoul Eastern District Court, Criminal Panel 12, opened the case on October 14, 2021. Kang, aged 56, told the court he accepted the charges and, asked whether the prosecution's account was right, answered yes in tears, Seoul Shinmun reported. He said he would accept any sentence, including death. He wrote to the court asking not to have a defense lawyer and asking that the indictment not be read aloud, and the court refused both, saying the procedures protect a defendant's rights and cannot be waived on request. Seoul Shinmun reported that at that first hearing he did not want a jury, and CBS Nocut News reported that in November 2021 he changed his mind and asked for one, saying the indictment distorted what he had done.
The jury trial took place on May 26, 2022, before presiding judge Lee Jong-chae, and ran from about 11 a.m. to about 10:40 p.m. Prosecutors argued that both crimes were premeditated and asked for the death penalty. Kang's defense did not dispute the facts but argued that the killings were impulsive, and that a man who had planned them would have found another way to get money, not surrendered. All nine jurors found him guilty. On the sentence, six voted for life imprisonment and three for the death penalty. The court noted that most jurors regarded the first killing as premeditated robbery-murder and the second as spontaneous, and it followed the majority.
In its reasoning the court called human life an absolute value that cannot be restored once lost, and it said the death penalty is an extremely exceptional punishment that may be imposed only where objectively clear circumstances justify it. It found none, citing his admission of the charges and his expressions of remorse. Kang was sentenced to life imprisonment on the seven counts of the indictment.
Prosecutors appealed. At the Seoul High Court, Criminal Division 3, with presiding judge Park Yeon-wook, they again sought the death penalty. On September 22, 2022 the court dismissed their appeal and left the life sentence in place.
The judges said that, given his record and the nature of the crimes, it was doubtful whether he could reform, and that the crimes went beyond what society can tolerate, so that the death penalty could appear fitting. They then gave reasons against imposing it: his surrender and admission of guilt, regret he had expressed, the possibility that the robbery-murder could not be fully shown to have been spontaneous or planned, and respect for the jury's view. They also pointed out that no execution had been carried out in South Korea since 1998 and that international human rights organizations classify it as abolitionist in practice, which raised doubts about the effect of a death sentence. The court added that parole for a prisoner like him is strictly limited, so that a life sentence would give him time to reflect and repent.
Life imprisonment was the sentence in force after the High Court ruling of September 22, 2022. A ruling by the Supreme Court is not on record, and a place of custody was not reported. As of September 2022 Kang remained under the life sentence imposed in May 2022.
The deaths came weeks after the Justice Minister, Park Beom-kye, had praised the monitoring program as highly successful. After the surrender he apologized and said the ministry had handled matters routinely and responded wrongly in some respects. He blamed a shortage of staff and budget and said the system had limits.
The monitoring system had been introduced in 2008. By August 2021, 281 officers supervised an average of 17.3 offenders each. The Justice Ministry counted 13 cases that year of people removing their devices, including Kang's, with two still at large; a count reported in March 2022 for the full year was 19. The strap material had been upgraded six times since 2008 without stopping removals. The penalty for destroying a device was up to seven years in prison or a fine of up to 20 million won, though offenders often received less than a year. The Korea Times editorial of September 1 reported that over five years 303 repeat sex crimes had been committed by offenders wearing devices.
The ministry announced measures on August 30, among them stronger materials for the devices, better cooperation with police, tougher punishments and more probation officers. On September 3 the Justice Minister announced a package that included a rapid response system for violations, supervision matched to risk level, and closer cooperation with prosecutors and police. Planned measures also included a legal amendment that would let investigators act at once and enter a residence when a high-risk offender removes a device and runs, a team at every probation office to deal with violations, information sharing with police, a better risk assessment, and expanded housing for high-risk released prisoners.
Critics said the plan repeated earlier ones. Law Times, in a reporter's column on September 9, compared it with a 2012 government plan made after attacks by device wearers, which had also promised a 24-hour response team and information sharing. The column argued that a determined offender can always remove a device and that the system should be reconsidered as a whole, with the United Kingdom's use of home confinement and European protective custody as reference points.
Experts at the time said much the same. Lee Yoon-ho, a police administration professor at Dongguk University, said the devices show where an offender is and not what the offender does, and that police learn of violations only after they occur. Seung Jae-hyun of the Korean Institute of Criminology proposed protective supervision in a separate facility after release. The debate revived protective custody, which Korea had abolished in 2005 over concerns that it amounted to double punishment. Jung Woong-seok, president of the Korean Association of Criminal Procedure Law, told Seoul Shinmun that the system had to balance the rights of offenders and victims.
Legislation moved slowly. A Location Information Act amendment introduced in November 2021 by a People Power Party lawmaker, Kim Do-eup, would have let police and probation offices obtain an offender's location from telecommunications providers after a device is tampered with. A Democratic Party bill by Kim Young-bae, introduced in October 2021, would have required probation offices to give police an offender's usual routes and family contacts on request. Kyeonggi Ilbo reported on February 6, 2022 that the first had waited nearly three months in committee without discussion, and Seoul Shinmun's Twig24 reported on March 10, 2022 that both bills remained stalled while two more devices were removed that month.
Some details differ. The Korea JoongAng Daily's report of September 7 placed the second killing on August 27, while the indictment and the court gave August 29. One Seoul Shinmun report gave the removal of the device as August 26; every other account, and the alarm records the paper itself cited, give August 27. Prosecutors gave the time of the second killing as about 3:30 a.m. and Segye Ilbo as about 3 a.m. The year of the 2005 sex offense sentence is given as 2005 by Segye Ilbo and 2006 by the Korea JoongAng Daily.
Whether either killing was planned was the central question at trial. Prosecutors and a majority of the jurors saw the first as premeditated and the second as spontaneous, while Kang said neither was planned. The Seoul High Court left open whether the robbery-murder could have been spontaneous.
1982: first prison term, for special theft, at age 17.
1996: sentenced to five years, with protective custody, for a robbery-rape offense.
2005: commits a second sex offense, five months after a release; sentenced to 15 years.
October 2020: enters protective custody at Cheonan Prison.
May 6, 2021: released from Cheonan Prison and ordered to wear a monitoring device for five years.
August 26, 2021: a woman in her 40s is killed in Songpa District.
August 27, 2021: curfew alarm at 12:14 a.m.; he removes the device at 5:31 p.m. and leaves.
August 29, 2021: a woman in her 50s is killed in the early hours; he turns himself in at about 8 a.m.
August 31, 2021: detention warrant granted.
September 2, 2021: police release his identity.
September 7, 2021: sent to prosecutors.
September 24, 2021: indicted on seven counts.
October 14, 2021: first hearing at the Seoul Eastern District Court.
May 26, 2022: jury trial; life imprisonment.
September 22, 2022: Seoul High Court dismisses the prosecution's appeal; life imprisonment stands.