Malaysia said Saturday that it would issue an arrest warrant for a North Korean diplomat if he refuses to cooperate with the investigation into the deadly attack on Kim Jong Un's exiled half brother. The investigation has unleashed a serious diplomatic fight between Malaysia and North Korea, a prime suspect in the Feb. 13 killing of Kim Jong Nam at Kuala Lumpur's airport. Malaysian police said Friday that the banned chemical weapon VX nerve agent was used to kill Kim, raising the stakes significantly in a case that has broad geopolitical implications. Experts say the nerve agent was almost certainly produced in a sophisticated state weapons laboratory and is banned under an international treaty. But North Korea never signed that treaty, and has spent decades developing a complex chemical weapons program. Kim was not an obvious political threat to his estranged half brother, Kim Jong Un. But he may have been seen as a potential rival in North Korea's dynastic dictatorship, even though he had lived in exile for years. North Korea has denied any role in the attack. Malaysia said earlier in the week that Hyon Kwang Song, a second secretary at the North Korean Embassy in Kuala Lumpur, was wanted for questioning. Abdul Samah Mat, the police chief leading the investigation, said authorities would give the diplomat "reasonable" time to come forward. If he doesn't, police will issue a notice compelling him to do so. "And if he failed to turn up ... then we will go to the next step by getting a warrant of arrest from the court," Abdul Samah told reporters. Malaysia hasn't directly accused the North Korean government of being behind the attack, but officials have said four North Korean men provided two women with poison to carry it out. On Saturday, the Indonesian suspect, Siti Aisyah, said she had been paid the equivalent of $90 for what she believed was a harmless prank. Aisyah, 25, said she had been introduced to people who looked like Japanese or Koreans who asked her to play a prank for a reality show, Indonesia’s Deputy Ambassador to Malaysia, Andriano Erwin, said. Asked whether she knew what was on her hands at the time of the attack, Erwin said: "She didn't tell us about that. She only said that it's a kind of oil, baby oil, something like that." Aisyah has said previously that she was duped into the attack, but Malaysian police say the suspects knew what they were doing. Experts say the women must have taken precautions so the nerve agent wouldn't kill them. Related: Kim Jong Nam Killed With VX, the ‘Most Toxic Weapon Ever’ An odorless chemical with the consistency of motor oil, VX is an extremely powerful poison, with an amount no larger than a few grains of salt enough to kill. It can be inhaled, swallowed or absorbed through the skin. Then, in anywhere from a few seconds to a few hours, it can cause a range of symptoms, from blurred vision to a headache. Enough exposure leads to convulsions, paralysis, respiratory failure and death. The killing of Kim Jong Nam took place amid crowds of travelers at Kuala Lumpur's airport and appeared to be a well-planned hit. Kim died on the way to a hospital, within hours of the attack. Also Saturday, police confirmed that a raid earlier in the week on the outskirts of Kuala Lumpur was part of the investigation. Abdul Samah, the police official, did not specify what authorities found there, but said the items were being tested for traces of any chemicals. Also Saturday, police confirmed that a raid earlier in the week on the outskirts of Kuala Lumpur was part of the investigation. Abdul Samah, the police official, did not specify what authorities found there, but said items were being tested for traces of any chemicals.