Japan provided fingerprint data to help Malaysian police establish Mr Kim Jong Nam's identity, the Kyodo news agency has reported.
Kyodo, citing unnamed sources, said the prints came from when Mr Kim was detained in Japan in 2001 for using a fake passport.
Malaysian police last Friday positively identified the man who died after being attacked at Kuala Lumpur International Airport 2 on Feb 13 as Mr Kim Jong Nam, the half-brother of North Korean leader Kim Jong Un.
The 45-year-old was travelling with a diplomatic passport bearing the name Kim Chol when he died.
North Korea insists that the dead man is Kim Chol, and that he died of a "heart stroke". This runs counter to the results of an autopsy which found that Mr Kim had been killed by the VX nerve agent, a deadly poison listed by the United Nations Chemical Weapons Convention as a weapon of mass destruction.
NORTH KOREANS MAY BE DEPORTED
In a short while, I will make a decision as to whether they will remain in detention or be deported back to North Korea. We will be rational in making any decision, so that it will bear the best result in terms of diplomatic relations and humanitarianism.
DEPUTY PRIME MINISTER AHMAD ZAHID HAMIDI, on the fate of the 140 North Korean overstayers in Sarawak.
Two women - an Indonesian and a Vietnamese - have been charged with murdering Mr Kim just before he boarded a flight to Macau by smearing the poison on his face.
Seven North Koreans are wanted by the police, including four suspects who left Malaysia on the day of the attack, and a senior diplomat believed to be hiding in the North Korean Embassy in Kuala Lumpur.
Malaysian Health Minister Subramaniam Sathasivam said yesterday that the government hopes Mr Kim's immediately family members will come forward to collect the body. "We are told that he has a wife, or wives, or children, so we hope that those people would respond and come forward to claim the body," he said.
Deputy Prime Minister Ahmad Zahid Hamidi, who is also the Home Minister, said that although there is no official request from Mr Kim's relatives to claim the body, the government will "consult the Attorney-General's Chambers and use several approaches to return his body to the next-of-kin".
Meanwhile, Malaysia said it may deport dozens of North Koreans in the country without valid work permits, even though the two countries have banned each other's citizens from leaving amid a tense stand-off over the murder of Mr Kim .
Datuk Seri Zahid said yesterday that he would decide soon on the fate of 140 North Korean overstayers in Sarawak, 37 of whom have been detained for working while on social visit passes.
"In a short while, I will make a decision as to whether they will remain in detention or be deported back to North Korea. We will be rational in making any decision, so that it will bear the best result in terms of diplomatic relations and humanitarianism," he said.
No details on his decision were available at press time.
Mr Zahid also said negotiations are ongoing to resolve the travel ban, which has left nine Malaysians - three diplomats and their family members - and at least 315 North Koreans stranded.
Foreign Ministry Secretary-General Ramlan Ibrahim, who heads the Malaysian negotiating team, told reporters yesterday that "internal consultations" have begun.
South Korea and the United States have accused North Korea of assassinating Mr Kim.
Pyongyang has denied the claim, and has accused the Malaysian authorities of subverting inves- tigations and conspiring with its enemies.
The diplomatic spat has led both sides to expel each other's ambassador. Pyongyang barred Malaysians from leaving North Korea last week.
Kuala Lumpur has done the same, and accused North Korea of holding its citizens hostage.