Malaysian authorities have rejected a plea to drop the murder case against Doan Thi Huong, the Vietnamese woman accused of killing the half-brother of North Korea's leader.
Vietnam had been pushing for her release, and the decision comes days after her Indonesian co-defendant, Siti Aisyah, was unexpectedly freed.
Both women insist they are innocent.
Kim Jong-nam was assassinated with liquid VX nerve agent at Kuala Lumpur airport in February 2017.
Ms Huong says she was tricked into taking part and believed she was part of a TV prank.
The 30-year-old, who could face the death penalty if convicted, sobbed in court when it was announced that her trial would go ahead.
Kim Jong-nam, the estranged half-brother of North Korea's leader Kim Jong-un, had been waiting to board a flight from Kuala Lumpur to Macau on 13 February 2017 when two women approached him in the departure area.
CCTV footage showed one of them placing her hands over his face, then both women leaving the scene.
Mr Kim died on the way to hospital from what was later found to be exposure to the nerve agent VX, one of the most toxic of all known chemical agents.