Malaysians Say Kim Jong-nam Was Killed by VX Nerve Agent

The poison used to kill Kim Jong-nam, the half brother of the North Korean leader Kim Jong-un, was VX nerve agent, which is listed as a chemical weapon, the Malaysian police announced Friday.

In a brief statement, Khalid Abu Bakar, the national police chief, said the substance was listed as a chemical weapon under the Chemical Weapons Conventions of 1997 and 2005, to which North Korea is not a party.

South Korea has suggested that the killing was the work of the North Korean government. The revelation that a banned weapon was used in such a high-profile killing raises the stakes over how Malaysia and the international community will respond.

VX nerve agent can be delivered in two compounds that are mixed at the last moment to create a lethal dose. The police say that two women approached Mr. Kim at the airport with the poison on their hands and rubbed it on his face one after the other.

Samples were taken from Mr. Kim’s skin and eyes. The poison was identified in a preliminary analysis by the Center for Chemical Weapons Analysis of the Chemistry Department of Malaysia, Mr. Khalid said.

The Chemical Weapons Convention bans the use and stockpiling of chemical weapons, and North Korea is among the world’s largest possessors of such weapons. In 2014, the South Korean Defense Ministry said the North had stockpiled 2,500 to 5,000 tons of chemical weapons and had a capacity to produce a variety of biological weapons. (The North has conducted five nuclear tests since 2006.)

VX is part of a family of nerve agents created decades ago during research into pesticides. It is tasteless and odorless and kills by causing uncontrollable muscle contractions, which eventually stop the victim from breathing. A dose of about 10 milligrams is enough to kill by skin contact, according to the Federation of American Scientists.

Several world powers, including the United States and the former Soviet Union, once had large stockpiles of the nerve agent. American stores of VX were destroyed under the Chemical Weapons Convention of 1997, with incineration completed in 2012.

In 1994 and 1995, the Japanese cult Aum Shinrikyo used homemade VX to attack three people, one of whom died.

North Korea is estimated to have a chemical weapons production capability of up to 4,500 metric tons during a typical year and 12,000 tons during a period of extended crisis. It is widely reported to possess a large arsenal of chemical weapons, including mustard, phosgene and sarin gas, a United States Congressional Research Service report said last year.

The announcement by Malaysia’s police chief came just a day after North Korea denied any responsibility for Mr. Kim’s death, accusing the Malaysian authorities of fabricating evidence of Pyongyang’s involvement under the influence of South Korea.

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. 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. And it gave no indication that it would agree to Malaysia’s demands to question a senior staff member at the North Korean Embassy in Kuala Lumpur in the investigation into Mr. Kim’s death.

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.

“I don’t believe Huong did such a thing,” said Doan Van Thanh, father of Doan Thi Huong, 28, a Vietnamese woman being held in Malaysia. “She was a very timid girl. When she saw a rat or frog, she would scream.”

Mr. Thanh, 63, said he had seen little of his daughter recently. He said she left the family’s home, in a village south of Hanoi, at 17 to attend community college, where she studied to be a pharmacist.

She later left Vietnam to work in Malaysia without telling her family and rarely visited, Mr. Thanh said. When she returned home in January for the Tet holiday, he said, she stayed only a few days.

On Thursday in Nghia Binh, Ms. Huong’s hometown, her brother, Doan Van Binh, said that she posted on Facebook under the alias Ruby Ruby. Her Facebook photographs and the attached location information appear to show that she had visited Malaysia twice since January, and her Facebook friends include several people who write in Korean.

Mr. Binh said that Ms. Huong had also appeared in a singing contest on the television show “Vietnam Idol” in 2016. In a short video clip, a panel of judges rejected Ms. Huong after she sang just one line: “I want to stop breathing gloriously so that the loving memory will not fade.”

North Korea has called for the release of Ms. Huong, an Indonesian woman and a North Korean man who are being held by Malaysia in connection with the death of Mr. Kim.

The statement on Thursday from the Jurists Committee was cited by the state-run Korean Central News Agency, in the first comment on the killing from the North’s official news media. The statement accused the Malaysian authorities of pursuing a case “full of loopholes and contradictions” that proved that its investigators “intended to frame us.” It said Malaysia had done so under South Korean influence.

The statement said Malaysia’s Foreign Ministry and the local hospital first told the North Korean Embassy in Kuala Lumpur that Mr. Kim had died of “heart stroke,” asking North Korea to take the body and cremate it.

But Malaysian officials’ attitude began changing after the South Korean news media, citing anonymous sources, reported that Mr. Kim had been poisoned, according to the North Korean statement.

“The Malaysian secret police got involved in the case and recklessly made it an established fact” that the death had been a poisoning, according to the North Korean statement, which did not refer to Mr. Kim by name.

The statement questioned how Ms. Huong and the Indonesian suspect in the killing, Siti Aisyah, 25, had survived if, as Malaysian officials said, they had used their hands to apply a deadly poison.