"On 22 June 1938, during the Great Purge, Korolev was arrested by the NKVD after being denounced by Ivan Kleymenov, Georgy Langemak, and Valentin Glushko. He was accused of deliberately slowing the work of the research institute, and following torture in the Lubyanka prison to extract a confession, was tried and sentenced to ten years in a labor camp. Korolev later learned that he had been denounced by Glushko, and this may have been the cause of the life long animosity between the two men."