A North Korean man being held in connection with the death of Kim Jong-nam has been released.
The Attorney General said there was insufficient evidence to charge Ri Jong Chol and he would now be deported from the country.
Mr Chol was arrested in Kuala Lumpur four days after the February 13 killing.
Malaysia has since charged two women - Indonesian Siti Aisyah and Vietnamese national Doan Thi Huon - with murder.
Police also want to question seven other North Koreans, including a senior official in the North Korean embassy in Kuala Lumpur.
Kim Jong-nam - the half-brother of North Korean ruler Kim Jong-un - collapsed and died shortly after he was attacked with the deadly toxin VX nerve agent in Kuala Lumpur airport.
VX is so toxic that even one touch would be enough to kill, an expert told ITV News.
The women charged with the murder told police they thought they were taking part in a harmless prank for TV. Aisyah said she was paid £73 to do it.
Malaysian prosecutors have said both women would face a mandatory death sentence if convicted.
Meanwhile, Malaysia said it was scrapping visa-free entry for North Koreans travelling into the country.