Malaysia's Prime Minister Najib Razak says his government's investigation of the killing of the North Korean leader's half-brother, Kim Jong Nam, will be "objective", as tensions rose between the countries.
Earlier on Monday, Malaysia said it had recalled its envoy from Pyongyang and summoned North Korea's ambassador in Kuala Lumpur, who again cast doubt on the impartiality of Malaysia's investigation into the murder and said the victim was not Kim Jong Nam.
"We have no reason why we want to do something to paint North Korea in a bad light, but we will be objective," Najib told reporters in Kuala Lumpur.
The son of Kim Jong Nam, 22-year-old Kim Han Sol, was expected to arrive in the Malaysian capital from Macau late on Monday.
Malaysian authorities have said they will release the body of the victim, believed to have been killed by North Korean agents, to the next of kin.
CCTV footage, released by Japanese broadcaster Fuji TV, appeared to show Kim Jong Nam being attacked at Kuala Lumpur International Airport last Monday by a woman believed to have wiped a fast-acting poison on his face. Watch that video above.
Kim Jong Nam, 46, who had been living in the Chinese territory of Macau under Beijing's protection, had spoken out publicly against his family's dynastic control of isolated North Korea.
South Korean legislators last week cited their spy agency as saying the young and unpredictable North Korean leader, Kim Jong Un, had issued a "standing order" for his half-brother's assassination.
Malaysian police said they were hunting four North Koreans who fled from the country on the day of the attack, having already detained one North Korean man, a Vietnamese woman, an Indonesian woman, and a Malaysian man.
At least three of the wanted North Koreans caught an Emirates flight to Dubai from Jakarta late on the day of the attack, an immigration official in Indonesia told Reuters.
Malaysia's Star newspaper reported that all four had returned to North Korea.
North Korea had sought to prevent Malaysia from conducting an autopsy, insisting the body be handed over. Its envoy in Kuala Lumpur criticised Malaysian authorities for "delaying" the release of the body.
"At the moment we cannot trust the investigation by the Malaysian police," ambassador Kang Chol told reporters after talks at the foreign ministry.
He said the embassy had only identified the victim as Kim Chol, based on the passport found on the dead man, and suggested a joint investigation with Malaysian authorities.
Malaysia is one of the few countries that maintains ties with reclusive North Korea, and the dispute could further isolate the impoverished state.
The mother of the detained Indonesian woman told Reuters that her daughter, Siti Aishah, had been duped into believing she was part of a television show or advertisement.
According to Malaysian media, the Vietnamese suspect, Doan Thi Huong, told police she had been tricked into taking part in what she thought was a practical joke.