In Feb. 2017, North Korean leader Kim Jong Un’s half brother was waiting at Kuala Lumpur International Airport when two women smothered him with lethal chemicals that left him dead in under 20 minutes. Police swiftly arrested a North Korean man in connection with the murder, copying his phone and other devices in the process.

That man is Ri Jong Chol, and he was never charged with the murder. But Ri is still part of a much bigger story: He is one of the hundreds of North Korean agents who help their home country survive tough economic sanctions