Malaysian police said preliminary toxicology tests found VX nerve agent on the eyes and face of Kim Jong-nam, the estranged half brother of North Korean leader Kim Jong-un, following his killing at Kuala Lumpur’s airport on February 13. Two women allegedly wiped chemicals across his face while he waited for a flight to Macau, where he lived with his family. He sought medical assistance, suffered convulsions and died while being transported to hospital. Investigators were examining additional evidence and trying to determine how the banned chemical entered Malaysia.

VX is an exceptionally potent nerve agent classified by the United Nations as a weapon of mass destruction and banned under the 1993 Chemical Weapons Convention. An oily, odorless liquid, it can penetrate the skin and disrupt nerve signaling; even a tiny quantity can be fatal. Symptoms can include vomiting, confusion, seizures and paralysis. Its persistence raised concerns about contamination at the airport, in the ambulance and at medical facilities. Authorities announced decontamination efforts roughly 11 days after the attack, during which tens of thousands of travelers had passed through the airport. No passengers, airport workers or medical personnel were reported ill.

Police said one of the two female suspects, a Vietnamese woman and an Indonesian woman, vomited after the attack. Their apparent ability to handle the substance and survive puzzled toxicologists. One expert suggested antidotes might explain their survival, although that possibility was unconfirmed. Investigators argued that the women’s immediate handwashing indicated awareness that they were handling poison. Relatives and acquaintances disputed that interpretation, insisting the women may have been deceived into participating.

Malaysia attributed the killing to North Korean agents and sought several North Koreans, including a senior embassy staff member and an employee of the state airline, Air Koryo. Reports differed on the number detained, placing it at three or four, including the two women. North Korea fiercely denied responsibility, accused Malaysia of fabricating evidence under South Korean influence, and challenged the investigation and post-mortem examination. It also refused to identify the deceased as Kim Jong-nam, whose passport bore the name Kim Chol. A statement attributed to a North Korean legal committee blamed Malaysia because the death occurred there and pointedly invoked North Korea’s nuclear status. Malaysia’s foreign minister threatened to expel the North Korean ambassador over his accusations, while custody of the body remained disputed.

Kim Jong-nam, the eldest son of former leader Kim Jong-il, was once considered a possible successor. His prospects faded after he was caught entering Japan on a false passport in 2001, and he later lived abroad and publicly criticized dynastic succession. His death sharply strained relations between two countries that had maintained relatively accessible travel and business ties.

The case also renewed scrutiny of North Korea’s chemical weapons capabilities. Outside estimates put its stockpile at 2,500–5,000 tons and annual production capacity at 4,500 metric tons, potentially rising to 12,000 during a crisis. North Korea has not signed the Chemical Weapons Convention and is believed to possess agents including VX, sarin, mustard and phosgene. The passages also recalled that Japan’s Aum Shinrikyo cult used homemade VX against three people in 1994–95, killing one.