The two women charged with killing the Kim Jong Nam appeared in a Malaysian court in bullet-proof vests on Thursday, as one of their lawyers warned they feared "trial by ambush" with police not sharing evidence.

Siti Aisyah, from Indonesia, and Doan Thi Huong of Vietnam are the only suspects in custody in the February 13 killing of Kim, the estranged half brother of North Korea's ruler. Four North Korean suspects fled the country the day of the murder, police say.

"Neither side may seek unfair advantage by concealing weapons behind its back. There should be no trial by ambush," Gooi said. 

The judge postponed the hearing until May 30. 

The women are accused of smearing Kim's face with banned VX nerve agent at a crowded airport terminal in Kuala Lumpur. But they say they were duped into thinking they were playing a harmless prank for a hidden-camera show. 

The women face the death penalty if convicted. 

Gooi said he fears the women will become scapegoats because all the other people believed to have knowledge of the case have left the country. 

The four North Koreans who flew out of Malaysia the day of the murder are believed to be back in Pyongyang. And another three who stayed inside their country's embassy in Kuala Lumpur to avoid questioning by police were allowed to fly home late last month after Malaysia struck a surprise deal with Pyongyang to ease tensions.

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Malaysian police have said they questioned the three men and found no grounds to hold them. But Gooi said today that at least one of those three men identified by police as Ri Ji U and known to Aisyah as "James" was key to her defence. 

"This amounts to a miscarriage of justice," Gooi said of Malaysia's decision to allow the men to leave the country. "They (the defendants) are already scapegoats." 

Gooi told The Associated Press yesterday that James recruited Aisyah in early January to star in his video prank shows. Over the course of several days, he had her rub oil or pepper sauce on a victim's face, "from forehead downwards," which he would film on his phone, the lawyer said. 

They practised at malls, hotels and airports, he said. Aisyah was paid USD 100-USD 200 for each prank and hoped the income would allow her to stop working as a social escort, Gooi said. 

Gooi said Aisyah flew to Cambodia in late January, where James introduced her to Hong Song Hac, one of four North Korean suspects who left Malaysia on the day of the murder. Hong had introduced himself as Chang, a Chinese who produces video prank shows for the Chinese market, he said.

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 Gooi said Hong asked Aisyah to do several more pranks at the Kuala Lumpur airport a few days before Kim was attacked. He said Aisyah met Hong at the airport on the day of the killing, and that Hong identified Kim to Aisyah and allegedly put the poison on her hand. 

Malaysia never directly accused North Korea of carrying out the attack, but speculation is rampant that Pyongyang directed a hit on a long-exiled member of its ruling elite. 

Tram Hux Hoang, a cousin of the Vietnamese suspect, said she is doing well in prison and had even gained weight. 

"The family and many Vietnamese people believe that she is innocent," he said outside court on Thursday. "We believe she was cheated and we hope that the truth will come out.