He was taken to an airport in Kuala Lumpur and will be sent back to the North via China, according to the reports.

"He is a free man. His remand has expired, and there is insufficient evidence to charge him," Attorney General Mohamed Apandi Ali was quoted by AFP as saying. "He has no proper (travel) documents so we will deport him."

Known as an expert in chemistry, Ri was arrested days after the murder on suspicions that he may have been involved in making the nerve agent used for the murder or may have helped others run away after the killing. He denied all the charges.

His release came a day after two detained Asian women were charged with murder. They were seen in CCTV footage obtained from the airport approaching Kim and rubbing a cloth on his face. Kim died within 20 minutes of being exposed to the lethal chemicals.

The women -- one from Indonesia and the other from Vietnam -- claimed they were taking part in a prank show. If found guilty, they could face the death penalty.

The North has denied any involvement, saying that South Korea and Malaysia are colluding to fabricate charges against the country.

In its diplomatic feud with North Korea over the murder that took place on its soil, Malaysia, which has maintained close ties with the reclusive state, has canceled its visa waiver program with the North. It will take effect starting next week, media reports showed.

Malaysia's foreign ministry strongly expressed concerns about the use of the banned chemical weapon VX nerve agent in connection with the case.

"The Ministry strongly condemns the use of such a chemical weapon by anyone, anywhere and under any circumstances. Its use at a public place could have endangered the general public," it said in a statement.

The ministry said that it is closely working with the Organization for the Prohibition of Chemical Weapons over the incident.

Malaysia will "fully cooperate with the OPCW and other international organizations to bring the perpetrators to justice," it added.

Malaysia has not directly blamed North Korea for the killing, but said that the eight suspects are North Korean nationals.

South Korea said that the North Korean regime is behind Kim's death, vehemently condemning Pyongyang for the use of the highly lethal chemical.

Seoul's unification ministry shrugged off concerns that the release of Ri would make it difficult to make North Korea take responsibility for the incident.

"Malaysia has said that it has clear evidence. We need to bear that in mind," Jeong Joon-hee, ministry spokesman, said at a press briefing. (Yonhap)