the nasa people have their own blue uniformed security guards, of whom canas velasco was one.of an unarmed team that recovered these weapons and arrested eight farc dissidents. the incident made him a target and in october, the father of six was assassinated in front of his wife. wearing this uniform increasingly requires courage. this man survived the ambush that killed cristina bautista. given what you have seen, and the dangers involved, why do you continue to do this? the violence is driven by the vast fortunes to be made getting cocaine from the mountains to the markets. this northern part of colombia, by the caribbean coast, is hugely significant for growing bananas. but the huge number of containers needed to send the bananas overseas provides a perfect opportunity for the drug smugglers to send cocaine abroad as well. this is the port of zungo embarcadero, a key smuggling spot. the shallow waters mean containers are carried by tugs to a floating port three hours away, where large ships will take them on to europe. i'm off to meet a man who sends up to a tonne of cocain