Kim Jong-nam died a painful death after being administered with a high dosage of chemicals with properties consistent with the VX nerve agent, said Health Minister Dr S Subramaniam said.
Authorities said Jong-nam, the half-brother of North Korean leader Kim Jong-un, was murdered at KLIA2 on Feb 13.
"He died in the ambulance (but) he fainted in the clinic (at the airport). I would say about 15 to 20 minutes," he said, when asked about the approximate time of death after exposure to the substance.
"The dosage (administered on Jong-nam) was so high and (spread) so fast, all over the body.
"It only takes 10mg to be lethal, but this one (was much higher). The agent had absorbed well through the skin," he said.
Subramaniam said that the body had shown signs of organophosphate poisoning and this was later confirmed by findings from the Chemistry Department report.
Organophosphates are used in insecticides, medication and nerve agents, with those poisoned showing symptoms like increased saliva and tear production, diarrhea, vomiting, small pupils, sweating, muscle tremors and confusion.
At the end of his explaination on how the chemical would have affected the body, Subramaniam was asked whether it would have been a painful death, to which he answered: "Yes."
Next of kin yet to claim body
Subramaniam said the full autopsy report would be submitted to the police for further action by next week.
"So far, in terms of cause of death, we have come to a conclusion and the report will be furnished to the police," he said.
He added that the identification of the victim remains a challenge as no next of kin have came forward to claim the body or provide their DNA for comparison.
"We will work with the police to see how the material can be attained.
"We also have the other ways of identification and each of them have different level of sensitivities," he said.
Among others, Subramaniam said the hospital could refer to dental structures or photo comparisons of physical marks including moles on the body.
"Once the identification is done and we get the next of kin then I guess our job is done," he said.
North Korean authorities have maintained that the identity of the deceased was Kim Chol, based on the diplomatic passport found in his possession.