Could a lapse in security between Kim Jong-nam’s security detail and Malaysian police have given two North Korean spies the opportunity to get close to him and poison him? That is the suggestion from a source familiar with the case, according to South Korea’s Yonhap News Agency. The agency quoted the source as saying that agents of the Reconnaissance General Bureau, North Korea’s spy agency, had carried out the killing by taking advantage of a security loophole created between Jong-nam’s bodyguards and Malaysian police at Klia2, which is Malaysia’s low-cost carrier airport in Sepang.

Jong-nam, 45, who was the eldest son of the late North Korean leader, Kim Jong Il, was said to have been killed by two women who are believed to be spies. He was reportedly poisoned by the two women at the airport, where he was scheduled to take a flight to Macau. Jong-nam is the half-brother of current North Korean leader Kim Jong-un.