Court officers, including the judge, donned face masks and gloves yesterday as samples of Mr Kim Jong Nam's blood, urine, liver tissues and other liquid tainted with the deadly nerve agent VX were presented.
The issue of what killed Mr Kim, the estranged half-brother of North Korean leader Kim Jong Un, was raised by the prosecution and the defence on the third day of the trial of two women murder suspects.
Mr Kim was murdered on Feb 13 at Kuala Lumpur's airport while waiting for his flight to Macau.
Indonesian Siti Aisyah, 25, and Vietnamese Doan Thi Huong, 28, are accused of smearing poisonous liquid on his face. The trial is taking place at the Shah Alam High Court in Selangor.
A post-mortem report says traces of the deadly VX nerve agent were found in Mr Kim's eyes, urine and blood, and also on his shirt and bag.
The prosecution said the nerve agent, which the United Nations has classified as a weapon of mass destruction, caused the death of the 45-year-old North Korean.
But the women's defence lawyers, who had earlier questioned if Mr Kim was killed by the VX nerve agent or by other means, yesterday again raised questions over the cause of his death.
An expert witness, clinical toxicologist Ranjini Sivaganabalan, told the court that decontamination from VX can be done by washing skin with soap and water. However, during cross-examination, she agreed with the defence lawyer that full decontamination may not be possible with soap and water alone.
"For VX, (reaction) is seconds to minutes. It depends on the temperature, and can take hours if it's in small amount," Dr Ranjini told the court, adding that a "dose that's too small would not be fatal".
Malaysian police said that, based on CCTV footage, four North Koreans are also suspects in the case.
The authorities said the four fled Malaysia within hours of the attack on Mr Kim. The prosecution included in their charge sheet on Monday that four unnamed men had committed the act of murder along with the two women.
The United States and South Korea have pinned the murder on the reclusive regime's leader. Pyongyang has denied the allegations and insisted that the deceased was a man named Kim Chol, not Kim Jong Nam, and that he died of a heart attack. Mr Kim Jong Nam was listed as Kim Chol in his diplomatic passport.
Earlier yesterday, a forensic pathologist who conducted the post-mortem on Mr Kim revealed that objection from the North Korean embassy had delayed the autopsy.
Dr Mohd Shah Mahmood, who first saw Mr Kim's body on Feb 14, had done the post-mortem only a day later. "It was delayed until there was a decision," he told the court.
When asked by defence lawyer Naran Singh if there was pressure involved, the pathologist agreed.
According to Dr Mohd Shah, an attempt was also made to obtain Mr Kim's medical records but it was not provided.
When Dr Mohd Shah said that Mr Kim died of VX poisoning, Mr Gooi Soon Seng, Siti's lawyer, said: "This is not for him to conclude. It's for the judge to decide if it was VX or not."