On 31 May 1937, the NKVD arrested Yakir, and transported him to the Lubyanka prison in Moscow. He and seven other major military commanders (Robert Eideman, Boris Feldman, Avgust Kork, Vitaly Primakov, Vitovt Putna, Mikhail Tukhachevsky and Ieronim Uborevich) were accused of being members of the alleged Trotskyist Anti-Soviet Military Organization and of being Nazi agents. Except for Feldman, who was cooperative, all of them got brutally tortured. Yakir (until they broke him) maintained his innocence, both in correspondence to Joseph Stalin and at his trial on 11 July. Although he generally admitted taking part in a conspiracy, he denied being a spy. During the trial he was asked to provide further details about his written confession but he stated that he couldn't add anything more. One of his last letters to Stalin is really moving. Stalin and other members of the Politburo made a following cynical comments on this, creating a written conversation: "Rascal and prostitute" (Stalin). Kliment Voroshilov and Vyacheslav Molotov added: "A perfectly accurate definition". Lazar Kaganovich finally wrote: "The only punishment for the scoundrel, riffraff and whore is death penalty".