A chemist told a Malaysian court Thursday that he discovered traces of a deadly nerve agent on the clothing of both women accused of killing Kim Jong Nam, the North Korean leader’s half-brother. The testimony of government chemist Raja Subramaniam was the first evidence linking Vietnamese suspect Doan Thi Huong and Indonesian suspect Siti Aisyah to the VX nerve agent blamed for Kim’s death. The women, accused of smearing the nerve agent on Kim’s face in Kuala Lumpur’s airport in February, have maintained that they thought they were taking part in a harmless prank for a TV show. Their defense team has previously argued that Kim, a possible rival to leader Kim Jong Un, may have been poisoned before he even arrived at the airport. Subramaniam’s testimony calls that argument into question. He said VX was found in its pure form on Huong’s jumper, while a degraded form was found on Aisyah’s clothing. The two suspects face the death penalty if convicted.