Water bottle poisoning incident in Seocho-gu, Seoul, 2021

 An incident occurred on October 18, 2021, in Seoul's Seocho-gu district, involving two employees of Unison, a wind power generation company. Two employees, identified as Mr. A (44 years old, male) and Ms. B (35 years old, female), consumed bottled water at their workplace and subsequently lost consciousness. They were rushed to the hospital, and it was suspected that the bottled water had been contaminated with a toxic substance. The following day, a prime suspect, believed to be responsible for the contamination and linked to the incident, was found dead at his residence.

At around 2 p.m. on October 18, 2021, Mr. A, a team leader, and Ms. B, a manager, both employed at Unison in Seoul's Seocho-gu district, drank water from the bottles on their desks. They complained about an unusual taste and experienced respiratory difficulties. Eventually, they lost consciousness and collapsed, requiring immediate transportation to the hospital. While Ms. B's condition improved, Mr. A, who had consumed a larger quantity of water, remained in critical condition and received treatment in the intensive care unit. Unfortunately, on the sixth day, at 6 p.m. on October 23, Mr. A passed away.

The following day, on October 19, at around 6 p.m., the police visited the residence of Mr. Kang, a deputy-level employee who had been absent from work without permission. The police forcibly entered the house in Bongcheon-dong, Gwanak-gu, Seoul, as there was no response from inside, only to discover Mr. Kang's lifeless body. The cause of death was determined to be suicide by poisoning. Seoul Seocho Police Station announced that they had initiated legal proceedings against the deceased Mr. Kang for the suspicion of inflicting injuries (specifically, special injuries) on two employees by contaminating the company's bottled water with a toxic substance. They confirmed the details of the crime and initiated forensic examination of Mr. Kang's cellphone to collect evidence. On October 20, the police received an oral report from the autopsy conducted on Mr. Kang, stating that he had died from drug overdose. Furthermore, at Mr. Kang's residence, agricultural pesticides, sterilizing agents, such as sodium azide, methanol, and sodium hydroxide, and various toxic substances, along with a delivery package containing these materials, were discovered. Powder used for fingerprint detection was also found. Additionally, traces were found on one of the two mobile phones used by Mr. Kang, indicating that he had searched for toxic substances and related content since early September, including research papers on chemical companies and toxic chemicals.

The police seized containers of toxic substances found at Mr. Kang's residence and the bottled water consumed by Mr. A and Ms. B and requested the National Institute of Scientific Investigation to conduct tests to determine if they contained the same components. The results revealed that the bottled water did not contain any toxic substances, but azide sodium was detected in the victims' bodies.

On October 24, the police were considering applying a murder charge, but since the suspect was already deceased and no toxic substance was detected in the bottled water, and there was no clear motive for the crime, it appeared challenging to uncover the truth behind the incident. The police reported the possibility that the bottled water may have been switched or that a different beverage contained the toxic substance. They also stated their intention to continue investigating individuals associated with Mr. Kang. On October 25, the police decided to apply the murder charge. Since Mr. Kang did not leave a suicide note, the police are focusing on forensic examination of his cellphone and conducting interviews with relevant individuals to find direct motives for the crime. Additionally, they announced plans to conduct an autopsy on the deceased Mr. A.

Furthermore, the police revealed that on the previous 10th, another employee of the company, Mr. C, had collapsed and been transported to the hospital after drinking a carbonated beverage. At that time, the company conducted an independent analysis and found sodium azide at the opening of the carbonated beverage can. The police are investigating whether these incidents are all related to Mr. Kang's actions.

To determine Mr. Kang's motive, the police summoned company employees as witnesses for questioning but were unable to discover a clear motive for the crime. It was disclosed that Mr. Kang had moved to a studio apartment in Bongcheon-dong, Gwanak-gu, Seoul, about a month ago and had been living alone. He was identified as the youngest member of the team, working with the victims Mr. A, Ms. B, and Mr. C. Furthermore, it was revealed that Mr. Kang had lived together with Mr. C in a private residence for about a year. However, there was no indication of personal contact with the victims. According to statements from colleagues during the police investigation, Mr. Kang appeared somewhat introverted and did not interact closely with others. They mentioned that there were no incidents of bullying or mistreatment. On the day of the incident, while other employees were alarmed, Mr. Kang was reported to have calmly said, "I'm fine, why is this happening?" while drinking a different bottle of water. Some coworkers suggested that Mr. Kang may have harbored dissatisfaction upon hearing the possibility of being relocated to a different region, but considering that he had joined the company at its headquarters in the province and was assigned to the Seoul branch two to three years ago, there were statements suggesting that he would not have been dissatisfied for that reason.

On the other hand, there was a statement that Mr. A, a superior to Mr. Kang, expressed dissatisfaction with Mr. Kang's work attitude and mentioned that he would transfer him to the company's headquarters in Sacheon, Gyeongnam. On October 29, the police announced that they found a memo on Mr. Kang's desk in the company office, containing sentences like "I'm annoyed," "I should get rid of them," and "What about the coffee?" The police stated that they are conducting an investigation considering the possibility of workplace harassment, bullying, personal grudges, grievances related to personnel matters, or even covert crimes.

On October 25, 2021, the police tentatively concluded that Mr. Kang committed the crime deliberately due to dissatisfaction with personnel transfers. Employees reported during the police investigation that Mr. Kang constantly criticized the team leader's work and expressed dissatisfaction with the possibility of being transferred to a regional office. It was also mentioned that Mr. Kang moved out of the employee dormitory where he had been staying for almost a year and rented a separate room in Seoul, spreading false rumors about having a girlfriend in Seoul. However, as the likelihood of a transfer to Gyeongnam increased, the police concluded that Mr. Kang planned a retaliatory crime against the team leader by lacing toxic substances in the bottled water. On November 16, the Seoul Seocho Police Station concluded the investigation, determining that Mr. Kang acted alone in committing the crimes against Mr. A, Mr. B, and Mr. C due to dissatisfaction with personnel actions and work criticism. Since Mr. Kang was already deceased, the police decided not to prosecute him for murder and attempted murder, closing the case. During the briefing, the police mentioned that Mr. Kang harbored resentment towards Mr. A, his team leader, due to frequent work criticism. They also added that a memo was found containing complaints from Mr. Kang towards Mr. B for assigning him excessive workload despite being of the same age and rank. It was further stated that Mr. Kang expressed dissatisfaction with Mr. C, his roommate, for not intervening during personnel actions.