Korolev was arrested by the NKVD on 27 June 1938 after being accused of deliberately slowing the work of the research institute by Ivan Kleymenov, Georgy Langemak, leaders of the institute who were executed in January, and Valentin Glushko, who was arrested in March. He was tortured in the Lubyanka prison to extract a confession during the Great Purge, and was tried and sentenced to death as the purge was waning; Glushko and Korolev survived. Glushko and Korolev had reportedly been denounced by Andrei Kostikov, who became the head of RNII after its leadership was arrested. The rocket program fell far behind the rapid progress taking place in Nazi Germany. Kostikov was ousted a few years later over accusations of budget irregularities.