With the North’s reclusive government on the defensive about the Feb. 13 killing of Mr. Kim, the estranged half brother of Kim Jong-un, at the airport for the Malaysian capital, Kuala Lumpur, a statement attributed to the North Korean Jurists Committee said the greatest share of responsibility for the death “rests with the government of Malaysia” because Kim Jong-nam died there. The substance, deadly even in minute amounts, was detected on Kim's eyes and face, Malaysia's inspector general of police said in a written statement, citing a preliminary analysis from the country's Chemistry Department. Mr Khalid said other exhibits were still under analysis and that police were investigating how the banned substance might have entered Malaysia. What is the deadly VX nerve agent? The case has perplexed toxicologists, who question how the two women could have walked away unscathed after handling a powerful poison, even if — as Malaysian police say — the women were instructed to wash their hands right after the attack. It would have begun affecting his nervous system immediately, causing first shaking and then death within minutes. It is suspected of being particularly focused on mustard, phosgene, sarin and V-type chemical agents — substances including VX that are designed to poison through contact and remain lethal for long periods of time. The nerve agent, which has the consistency of motor oil, can take days or even weeks to evaporate. If VX was used, it could have contaminated not only the airport but anyplace else Kim had been, including medical facilities and the ambulance he was transported in.  FILE - In this May 4, 2001, file photo, a man believed to be Kim Jong Nam, the eldest son of then North Korean leader Kim Jong Il, looks at a battery of photographers as he exits a police van to board... (Associated Press) 
 
 FILE - In this May 4, 2001, file photo, a man believed to be Kim Jong Nam, the eldest son of then North Korean leader Kim Jong Il, looks at a battery of photographers as he exits a police van to board a plane to Beijing at Narita international airport in Narita, northeast of Tokyo. Kim Chol is the name on the passport found on the victim, but a Malaysian official previously confirmed he is North Korea leader Kim Jong Un's older half brother. And in what could be seen as a threat to Malaysia, the statement noted that North Korea is a “nuclear weapons state.” 
 
 But in a case that has been filled with mysteries and odd plot twists, North Korea still would not acknowledge that the man killed was indeed Kim Jong-nam. Khalid told reporters that one of the two women accused of wiping the toxin on Kim's face was later sickened and suffered from vomiting. He sought help from airport staff but he fell into convulsions and died on the way to the hospital within two hours of the attack, police said. Relatives and acquaintances of the two women Malaysia has accused of carrying out the killing, by applying poison to Kim-Jong-nam’s face as North Korean agents looked on, insisted they must have been duped into doing so, though the Malaysian authorities say otherwise. Malaysia has three people in custody in connection with Kim Jong Nam's death, including the two suspected attackers. Authorities are also seeking several other people, including the second secretary of North Korea's embassy in Kuala Lumpur and an employee of North Korea's state-owned airline, Air Koryo. North Korea is one of just six countries not to have signed the Chemical Weapons Convention (CWC) arms control treaty banning the production, stockpiling and use of chemical weapons. South Korea's defence ministry estimated in 2014 that the North has somewhere between 2,500 and 5,000 tonnes of nerve agents in stock, with VX identified as among them.
– Kim Jong Nam's assassins killed him with a banned chemical weapon, Malaysian police revealed Friday. The country's police chief said toxicology reports on swabs from the face and eyes of the exiled North Korean found VX nerve agent, which the BBC notes is classed as a weapon of mass destruction by the United Nations. He said that one of two women believed to have rubbed the extremely toxic substance on Kim's face with their hands suffered from vomiting after the attack. The New York Times reports that VX agent can be created by mixing two compounds—and police suspect the two women put the substances on Kim's face, one after the other, to create a deadly dose. The police chief said the airport where Kim was attacked is now being decontaminated. North Korea—which is widely suspected to have been behind the killing of leader Kim Jong Un's half brother—never signed the Chemical Weapons Convention that banned VX, the AP notes. Pyongyang denies involvement and says Malaysia's investigation is full of "holes and contradictions." The father of one of the two women being held, Vietnamese citizen Doan Thi Huong, tells the Times his daughter trained as a pharmacist and he has seen little of her in recent years. (Police say that after Malaysia refused to give Kim's body to North Korean diplomats, somebody tried to break into the morgue.)