In Biggles and the Blue Moon, Cortello was the name of one of three American bandits who planned to seize the pearl collection of Lin Seng. Together with fellow gang members sosbell and Sam, the three had set up camp in the jungles surrounding Taihan, the remote countryside villa belonging to Lin Seng. By controlling the only access road and cutting off the telephone line, they laid siege to Taihan and warned Lin Seng that he would only be allowed to leave the location if he left his pearls behind.
Biggles first met Cortello when he, Algy and Ayart were surveying the Taihan golf course as a possible landing strip. Cortello had crossed over into the Taihan compound by means of a fallen tree which spanned the crocodile infested gulley between the jungle and the Taihan golf course and waited in the golf pavilion in the hope of meeting Biggles. He believed that Biggles, like himself, was after the pearls, and he wanted to cut a deal. He suggested that they cooperate since there was plenty to spare between them. Biggles, obviously sent him packing.
The next day, Biggles met Cortello again at the fallen tree. Again, Biggles had to warn him off the Taihan property but this time he added some news (recently delivered by Mr Tong) about 50 Indonesian commandoes which had landed on the coast and were headed for Taihan. They were as much a threat to Cortello's gang as they were to Taihan, and Biggles had hoped to warn him off. Not surprisingly, Cortello disregarded the advice and went on his way.
Biggles met Cortello again later the same night. This time, Biggles was attempting to leave Taihan in order to reach Kuala Lumpur collect his Auster aircraft. His car was ambushed by the gang and he was taken prisoner. Biggles took the opportunity to introduce whatever friction he could between the members of the gang. Sosbell, in particular, was alarmed to hear what Biggles had to tell him about the approach of the party of Indonesian commandoes, and upset that Cortello had not bothered to tell the rest of them.
When Cortello wanted to go nearer to Taihan to scout out what was happening there, Sosbell, not trusting Cortello, sent Sam to shadow him. During Cortello's trek to the fallen tree, he stumbled into a detachment of the Indonesian commandoes and was shot at. Fleeing in the direction of Taihan, he crossed over to the golf course and asked Algy for sanctuary. Algy would, of course, have nothing to do with him, but decided Cortello could do something useful by sending him to guard the fallen tree and give a warning if the Indonesians should approach.
Sam, seeing Cortello talk to Algy, believed that the gang was being double-crossed and so murdered him. Algy discovered Cortello's body by the fallen tree but when he returned with some pthers to bury the body, it was no longer there. Sam later told Biggles that he had disposed of it by tipping it into the gulley for the crocodiles.