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KUALA LUMPUR, Malaysia — Two women accused of assassinating the estranged half-brother of North Korean leader Kim Jong Un with a banned nerve agent pleaded not guilty at the start of their high-profile murder trial in a Malaysian court on Monday.

Siti Aisyah, 25, of Indonesia, and Doan Thi Huong, 28, of Vietnam, are charged with killing Kim Jong Nam by smearing his face with VX, a chemical poison banned by the United Nations, at Kuala Lumpur's international airport on Feb. 13.

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Both women wore bulletproof vests as they were led into the court on the outskirts of the Malaysian capital. They face the death penalty if convicted.

The prosecution said in its charge sheet that their actions showed "intent to kill the victim" by smearing his face and eyes with VX nerve agent, which a post-mortem confirmed had killed Kim.

Defense lawyers demanded that the prosecution immediately name four other suspects who have also been charged in the case but who are still at large. The prosecution said their identities would be revealed during the trial.

Doan Thi Huong of Vietnam, left, and Siti Aisyah of Indonesia in arrest photos. Royal Malaysia Police / EPA

The women had told their lawyers that they didn't know they were participating in a deadly attack and that they believed they were carrying out a prank for a reality TV show.

They had carried out several practice runs at shopping malls in Kuala Lumpur ahead of the attack, the prosecution said.

South Korean and U.S. officials have said Kim Jong Un's regime was behind the murder. North Korea denies the allegation.

The trial is expected to run until Nov. 30 and the prosecution is expected to call up to 40 witnesses.