PAX research pushed the boundaries of protoss science and Nubas was sealed in a nutrient tank and experimented upon in order to unlock inherent genetic potential. However, his gene-key was missing a fundamental helix strand, resulting in his mutation and death.
Despite this, his legacy lived on when a sample of creep was brought to the facility. Due to a virus injected by the scientists, it became a "psionic predator", using their memories of Nubas against them. Some of the scientists believed Nubas experimented on himself, while others believed they forced the experiment on him.