Kim Jong-nam, the first son of late former leader Kim Jong-il, was killed at an airport in Malaysia on Feb. 13 after two Asian women allegedly wiped a toxic substance on his face.

VX, one of the most toxic chemical warfare agents, is tasteless and odorless, according to a website of the US Center for Disease Control. Exposure to the agent can cause death in minutes, it said.

Police said Wednesday that the two female suspects -- Vietnamese and Indonesian -- were aware that they took part in the attack and smeared the chemical on Kim's face with their bare hands but claimed they were deceived into thinking that they were part of a comedy show. The two women washed their hands after the attack.

Malaysian police said that besides the two women, a total of eight North Koreans are suspected of being involved in Kim's murder.

Four North Korean men fled Malaysia on the day of Kim's death and are now believed to have escaped to Pyongyang. Police arrested a North Korean man while looking for three others, including a diplomat and an employee at Air Koryo, the North's flag carrier.

South Korea said that it is highly likely that the North Korean regime is behind Kim's killing. North Korean leader Kim Jong-un issued a standing order to kill his brother after assuming power in late 2011.

In its first official response, North Korea said Thursday that Malaysia colluded with South Korea in its investigation into the killing of Kim Jong-nam, claiming that Seoul is masterminding an anti-North Korea conspiracy. (Yonhap)