Jack Soble

Soble himself was sentenced to a seven-year sentence, which he began serving at Lewisburg Prison. In 1958, Soble intentionally swallowed more than a pound of nuts and bolts, in what was characterized as a suicide attempt but which Soble later claimed was a protest against prison conditions. In 1961, Soble testified against his brother, despite attempts by Robert's attorney to have Soble declared mentally incompetent. His brother committed suicide in 1962, and shortly thereafter, Soble was released early for good behavior.

While awaiting trial, Soble attempted to commit suicide and government attorneys described him as a "psychopathic personality." After a trial, both Soble and Myra Sobre, along with their associate Jacob Albam, were convicted on espionage charges and sentenced to prison. Myra Soble received a five-and-a-half year prison sentence for her role in the espionage ring. On October 8, 1957, Federal Judge Richard H. Levet, United States District Court, Southern District of New York, reduced her sentence to four years. Soble was found to have been informing the Soviet Union about aspects of the United States' national defense.

The seeds of Soble's downfall came in 1947, when founding member of the ring, Boris Morros confessed to FBI agents that he had been working as a Soviet spy. Morros agreed to operate as a double agent, betraying Soble and the other members of the ring. Both Soble and his wife, Myra, were arrested in 1957. Morros also named Jane Foster Zlatovski, her husband George Zlatovski, Alfred Stern, Robert Soblen, and Jacob Albam as members of the espionage ring that Soble participated in.

Soble arrived in 1941, and took over supervision of an NKVD spy ring known as the "Mocase", replacing Vasily Zarubin who under the pseudonym "Vasili Zubilin" became the head of the NKVD in the United States.

In 1940, Soviet spymaster Lavrenty Beria dispatched the entire Soble family to the United States, by way of Japan and Canada. Soble later testified that Beria had told him that if he undertook the mission to spy on the United States, Beria would allow Soble's entire family to leave the Soviet Union.

Soble would claim decades later that he was coerced by Soviet agents to become a spy in 1931 after his wife returned to the USSR to visit her sick mother and threats to her safety were made if he did not cooperate. These claims are considered suspect as there is evidence that Soble had earlier contact with Stalin's agents.

Soble, who now adopted the name Abraham Senin, became publicly known as a prominent member of the German Trotskyist circle, visiting Leon Trotsky himself on at least two occasions. On a mission to gather intelligence on Stalin's opponent Leon Trotsky, Soble visited Trotsky in Prinkipo, Turkey in 1931 and in Copenhagen, Denmark a year later. However, suspicions were aroused about his activities and Trotsky booted Senin and his brother Robert from the party. Soble returned to the USSR and began working for Profintern.

Jack Soble (May 15, 1903 – 1967) was a Lithuanian who, together with his brother Robert Soblen, penetrated Leon Trotsky's entourage for Soviet intelligence in the 1920s. Later, in the United States, he was jailed, with his wife Myra, on espionage charges. He was born in Vilkaviskis, Lithuania as Abromas Sobolevicius and sometimes used the name Abraham Sobolevicius or Adolph Senin.

Soble was born in 1903 as Abromas Sobolevicius in, then-Russian controlled, Lithuania to a wealthy Jewish family. Soble travelled to Leipzig, Weimar Republic in 1921, to attend college, while there he joined the German Communist Party. In 1927 he travelled to the Soviet Union marrying before returning to Germany. Soble studied briefly at the University of Berlin where he became a Trotskyist which led to his expulsion from the Communist Party and the university.