 Rubin served most of his prison term in solitary confinement, during which he continued his research as best as he could.When he fell ill with a suspected cancer, he was removed to a hospital and encouraged to make further confessions in return for favourable treatment, but declined the offer.He was released on a commuted sentence in 1934 and allowed to work in Aktyubinsk, Kazakh SSR as an economic planner.