In Biggles in Mexico, Carlos Cornelli, also known as "Corny" was a member of the diamond robbery gang which took refuge in the village of Eltora in Mexico. Originally a guitar player in a dance band, Corny came from South America to work in London and stayed on after the rest of the band went home. He continued working in various shady night clubs and was believed to have gone into drug peddling. Subsequently he was recruited by Nicolas Brabinsky, otherwise known as "Ritzy". Together with a cockney Samuel Brimshawe ("Nifty") and possibly with another Londoner David Adamson ("Tricky"), the gang conducted a diamond robbery which resulted in a caretaker being shot.
The gang made off with some 150 to 250 thousand pounds worth of industrial diamonds and boarded a boat which Ritzy had prearranged, and headed for Tangier where they were to meet a diamond buyer. The boat broke down in the Bay of Biscay but they were picked up by a French tramp steamer and taken to New Orleans. From there the gang made their way to San Francisco where they made another appointment to meet with a diamond buyer, an East German named Hugo Schultz. However, nervous about the possible attention from the U.S. authorities, Ritzy took the gang across the border to wait for Schultz in Eltora, Mexico.
Biggles first met Corny at the Casa Grande posada when he arrived, undercover, at Eltora on the trail of the gang. Corny was drinking with the local policeman, Juan and gave Biggles some advice about how to deal with the local police--that a bribe was often expected.
In Eltora, Corny had been defying Ritzy's orders by romancing Margarita, the daughter of an elderly naturalist and fiancee of a wealthy local gentleman José Fonderi. The night after Biggles arrived, he and Ginger found Corny serenading Margarita with a guitar. Subsequently a shot was heard and Corny was found dead. At first, suspicion for the shooting fell on José but when Biggles was shown the bullet by Juan, he saw that it was a hard-nosed slug which had come from an automatic and not a soft-nose .45 such as the revolver which José carried would use. Biggles told this to José who susbsequently used this fact to clear himself. José had also seen Ritzy at the scene of the murder and his testimony and the evidence of the bullet led to Ritzy being arrested.