In Biggles at World's End, Juan Vendez was the assistant manager and customs officer at the airport of Punta Arenas in Chile. Vendez was an officer in the Chilean Customs and Excise service. As part of his training, he had spent a year living in England and also in Germany and France in order to learn the languages necessary for his work. Consequently he spoke English well. Vendez came from the warmer climate of in the north of Chile and had been posted to Punta Arenas as part of a mandatory rotation for Customs Officers. Punta Arenas was not, he explained to Biggles, the kind of popular station anyone would volunteer for. At the time he met Biggles and co. he only had a few more months before returning to Santiago.
Vendez befriend Biggles and co. after they received a cold and hostile reception from the airport manager Hugo Gontermann. Apologising for Gontermann's behaviour, he explained that Gontermann was a bit of a bully and that the airport staff did not like him either. Gonntermann's German background might also explain his hostility to anyone British. Vendez drove Biggles and co. into town after their arrival, and recommended a hotel for them and also connected them with Mr Scott, a ship's chandler who might be able to provide them with more information on Carter and Barlow, two missing British botanists which Biggles was ostensibly searching for.
Towards the end of the book, when Gontermann had caused Biggles to be ground by sending a unsubstantiated report about him being a spy, Biggles appealed to Vendez, in Gontermann's absence, to allow him to complete one last flight. He asked Vendez to "turn a blind eye", promising to return to be interviewed by the security officials who were coming down from the capital. Vendez was satisfied with Biggles' word as an Englishman that he will come back and so told Biggles "I know nothing. I see nothing".
After the flight, Biggles returned as promised. By the time, Vendez had found out Biggles' true mission because Biggles had left Carter and Barlow's diary with him to be dried. Nonetheless, the meeting between Vendez, Biggles and the Chilean security officials proceeded amicably and Biggles was allowed to leave for Britain. Biggles, grateful to Vendez for his helpfulness, left him a car he had bought for transportation in Punta Arenas. Later, Biggles also kept his promise to remember Vendez's good services and sent him another present from London.