Karl was a Neo-Nazi paramilitary who worked for de Flores in South America in 1988. He was in charge of monitoring the trajectory of Nemesis. When the comet containing the statue came down in Windsor, he hurriedly informed de Flores. He and several other Neo-Nazi soldiers accompanied de Flores to England with the aim of taking the statue.
During an ensuing confrontation with a group of Cybermen who also wanted Nemesis, Karl was the only one of de Flores' men who didn't die in the firefight with the Cybermen. He risked his life to retrieve the carrying case containing Nemesis' silver bow, although neither he nor de Flores suspected that the Doctor had already removed the bow from within and the case was empty.
Karl remained with de Flores for the rest of their time in England. He accompanied him on his sojourn to make an alliance with the Cyber Leader, and when the Cybermen betrayed the Nazis and attempted to convert de Flores into one of them, Karl freed his superior and the pair eventually found their way to the abandoned aircraft hangar where the Nemesis had been moved. Karl held the Doctor and Ace at gunpoint while de Flores attempted to claim Nemesis' power for himself, but both of he and de Flores were shot down and killed by the Cyber Leader.