[citation needed] Soble travelled to Leipzig, Weimar Republic in 1921, to attend college, while there he joined the German Communist Party.

[3][4] 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.

[3] 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.

[3][6] 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.

[8] After their arrest, the Sobles were interviewed numerous times, Jack at the Federal Correction Facility in Danbury, Connecticut and Myra at the Women's House of Detention, in New York City, where they provided some information.

The Sobles revealed that they had traveled to Russia, Lithuania, Germany, France, Switzerland, Austria, Japan, Canada, and the United States on behalf of Soviet intelligence.