Specimen Six Sigma was one of twelve Kaled mutants who were captured by human military forces and contained within the Dalek Dome on Earth, their memory being used to create psychoscapes based on Dalek history as a tourist attraction. Six Sigma's memory was the basis of a psychoplasm-based Red Supreme Dalek who led a simulated 1966 Dalek invasion of Earth.
All twelve mutants survived the brief 2323 Dalek invasion of Earth caused when simulacra from the Dalek Dome briefly manifested in reality. Dalek Studies expert Georgette Gold reflected that they were still "dreaming of conquest" as the Fourteenth Doctor took his leave, placing the matter of whether or not to destroy the mutants onto her. (COMIC: Liberation of the Daleks [+]Loading...["Liberation of the Daleks (comic story)"])