north korean construction headquarters just outside the namibian capital. >> reporter: a quick drive away from its picturesque downtown, behind this high-walled warehouse, namibia's sleepy capital holds a secret. when did the north koreans leave? >> maybe let me say maybe two weeks or three weeks. >> reporter: two week ago they left? >> yes. >> reporter: and who was operating there? the north koreans? >> yes. >> reporter: just weeks ago say eyewitnesses, north koreans living and working in this sprawling compound, in clear violation of u.n. sanctions. they grew their own food, moved in and out with trucks. then they vanished. but the building's title deed shows it's a headquarters of north korean state company mansude. as sanctions have squeezed, the north korean regime searched globally for foreign cash to fund its nuclear and missile program. and across africa, they found