KUALA LUMPUR: North Korean leader Kim Jong-Un's half brother was assassinated with a lethal nerve agent manufactured for chemical warfare, Malaysian police said Friday.
Releasing a preliminary toxicology report on Kim Jong-Nam's murder at a Kuala Lumpur airport, police said the poison used by the assassins was the odourless, tasteless and highly toxic nerve agent VX.
Traces of VX - listed as a weapon of mass destruction by the United Nations - were detected on swabs of the dead man's face and eyes.
Malaysia requests Interpol alert on four N Koreans over airport murder
Leaked CCTV footage from the brazen attack on February 13 shows the portly Kim being approached by two women who appear to put something in his face.
Moments later he is seen asking for help from airport staff, who direct him to a clinic.
Malaysian police said he suffered a seizure and died before he reached hospital.
The national police chief said Friday detectives would look for the source of the deadly VX.
"We are investigating how it entered the country," Khalid Abu Bakar said.
"The chemical is illegal. It is a chemical weapon."
However he added that "if the amount of the chemical brought in was small, it would be difficult for us to detect".
Malaysia says cause of Kim Jong Nam’s death still unknown
A leading regional security expert told AFP it would not have been difficult to smuggle VX in a diplomatic pouch, which are not subject to regular customs checks.
North Korea has previously used the pouches "to smuggle items including contraband and items that would be subjected to scrutiny if regular travel channels were used", said Rohan Gunaratna, the head of the Singapore-based International Centre for Political Violence and Terrorism Research.
He added North Korea has manufactured VX in the past.
"The North Korea intelligence service has been very active in Thailand, Malaysia and in Indonesia and today pose a threat to the region," Gunaratna said.
Khalid has previously said the woman who ambushed Kim from behind clearly knew she was carrying out a poison attack, dismissing claims that she thought she was taking part in a TV prank.
"The lady was moving away with her hands towards the bathroom," Khalid said earlier this week.
"She was very aware that it was toxic and that she needed to wash her hands."
Under the international Chemical Weapons Convention 1997, countries must declare stockpiles of VX and are obliged to progressively destroy their supplies, although North Korea is not a party to the treaty.
In his brief written statement released Friday, Khalid said scientists were continuing to analyse "other exhibits" from the autopsy.
Malaysian detectives are holding three people -- women from Indonesia and Vietnam, and a North Korean man -- but want to speak to seven others, four of whom are believed to have fled to Pyongyang.
One man wanted for questioning, who is believed to be still in Malaysia, is a senior North Korean embassy official.
Police have acknowledged that his diplomatic status prevents them from questioning him unless he surrenders himself.
North Korea's state media broke a 10-day silence Thursday on the murder, launching a ferocious assault on Malaysia for "immoral" handling of the case and for playing politics with the corpse.
The North's official KCNA news agency said Malaysia bore prime responsibility for the death, and accused it of conspiring with South Korea.
No next-of-kin have yet come forward.
North Korea has never acknowledged the victim as the estranged brother of leader Kim Jong-Un and the lengthy KCNA dispatch avoided any reference to the dead man's identity, calling him only "a citizen" of North Korea "bearing a diplomatic passport".
The only known use of VX is as a chemical warfare agent and the US government's Centers for Disease Control and Prevention (CDC) describes it as the "most potent" of all nerve agents.
"It is possible that any visible VX liquid contact on the skin, unless washed off immediately, would be lethal," the CDC said on its website.
All nerve agents cause their toxic effects by preventing the proper operation of an enzyme that acts as the body's "off switch" for glands and muscles.
Without that switch, the glands and muscles are constantly being stimulated, and eventually tire and become unable to sustain breathing.
Kim Jong Nam murder case: North Korea calls for release of three detained in Malaysia
Saddam Hussein was accused of using the agent during the 1980s.
VX was used by Japan's Aum cult in the 1994 murder of an office worker in Osaka, and in the attempted murder of two other people.
The doomsday cult led by guru Shoko Asahara used sarin nerve gas for a deadly attack on the Tokyo subway in 1995. Asahara was sentenced to death for the subway murders as well as producing deadly substances, including sarin and VX.