Deadly VX nerve agent was found on the clothing of both women charged with murdering the half-brother of North Korean dictator Kim Jong-un.
Testifying during the trial into the murder of Kim Jong-nam in Malaysia, a chemist has said he found traces of VX nerve agent on the clothes of Doan Thi Huong, from Vietnam, and Indonesian Siti Aisyah.
The pair are suspected of smearing Kim Jong-nam's face with the deadly toxin at a crowded airport terminal in Kuala Lumpur.
Shortly after the attack on February 13, Mr Kim collapsed and died.
Both women have pleaded not guilty to murder and said they thought they were playing a harmless prank for a hidden-camera show, with Aisyah saying she was paid £73 to do it.
Malaysian prosecutors have said both women would face a mandatory death sentence if convicted.
VX is so toxic that even one touch would be enough to kill, an expert told ITV News.
Speaking in court, government chemist Raja Subramaniam said he found VX in its pure form and VX precursors on Doan Thi Huong's jumper, which was seen in airport video emblazoned with the word LOL on the front.
The chemist also told the court he found degraded VX on cuts of Huong's fingernails and on Aisyah's clothing.
Defence lawyers previously said they fear the two women will become scapegoats because other people who are believed to have knowledge of the case have fled Malaysia.
Police in the country said four North Korean suspects fled Malaysia on the day of the killing.
Both the Indonesian and Vietnamese governments have hired lawyers to defend the women.
According to Aisyah's lawyer, Gooi Soon Seng, the 25-year-old did not know she had poison on her hand when she smeared Mr Kim's face.
Instead she will argue that she was the victim of an elaborate trick.
Little is known about 29-year-old Huong.
Although Malaysia has never directly accused North Korea of carrying out the attack, speculation is rampant that Pyongyang orchestrated the hit on a long-exiled member of its ruling family.
It is reported that Kim Jong-un had never met his half-brother.
Although Mr Kim, who was estranged from his family, was not an obvious political threat, he may have been seen as a potential rival in the country's dynastic dictatorship.
North Korea has denounced the speculation and has not even acknowledged that the dead man was Kim Jong-nam.
The secretive state has suggested the victim died of a heart attack and accused Malaysia of working with South Korea and other "hostile forces" in blaming Pyongyang.
The trial is expected to last for two months.