The formal autopsy of North Korean leader Kim Jong-un’s half brother, Kim Jong-nam, has finally revealed what was the lethal substance which had been used by the assassins at the Kuala Lumpur airport in Malaysia.

Malaysian police on Friday said that a particular nerve agent called VX had been used by the assassins allegedly sent from North Korea. “The chemical substance on the exhibits has been identified as. . . VX nerve agent,” Khalid Abu Bakar, Malaysian inspector general of police, said.

Considered twice as more toxic than sarin, the VX nerve agent is one of the most toxic and fastest acting chemical warfare agents, according to the US Centers for Diseases Control and Prevention. The CDC says that if the skin is exposed to VX and not washed off immediately, the result would be fatal for the victim.

“Exposure to a large dose of VX can cause convulsions, a loss of consciousness and respiratory failure possibly leading to death,” the CDC says.

It is believed that the nerve agent was used by Bashar al-Assad’s regime in Syria and was classified as a chemical weapon. VX was also used by Saddam Hussein against Kurds.