He was declared persona non grata after one semester and returned to the Bronx, where he became a full member and organizer for the American Communist Party.

[3] In 1937, Cohen joined the Mackenzie–Papineau Battalion and fought as a foreign national volunteer in the Spanish Civil War, as did others who were sympathetic to the anti-Franco movement.

He was discharged from the Army in November 1945 and returned to the United States where he resumed his espionage work for the Soviet Union.

While in Poland, Morris and Lona engaged in numerous foreign missions for the Soviet Union, traveling to Japan, Hong Kong, Australia, New Zealand, Austria, Belgium, and the Netherlands.

[3] In 1954, the Cohens moved to 45 Cranley Drive in Ruislip, Middlesex where they had numerous pieces of hidden equipment for espionage, and an antenna looping around their attic, used for their transmissions to Moscow.

[1] British security officials arrested the Cohens on January 7, 1961, for their part in a Soviet espionage network known as the Portland spy ring that had penetrated the Royal Navy.

[1] Files released by the National Archives in September 2019 indicated that MI5 had found "espionage equipment hidden inside an oversized Ronson cigarette lighter" in a bank safety deposit box according to The Times; this became the breakthrough required to close down the spy ring.

[6] Both the United States and the UK had conducted such exchanges before, such as Soviet spy Rudolf Abel for U2 pilot Gary Powers, and Konon Molody for Greville Wynne in 1964.

But In this case, the opposition criticised Harold Wilson's Labour Government for agreeing to release dangerous Soviet agents, such as the Krogers (i.e., the Cohens), in exchange for Brooke, described as a propagandist.

British playwright Hugh Whitemore dramatized the case as Pack of Lies, which was performed in London's West End, starring Judi Dench and Michael Williams.

The play was produced on Broadway for 3½ months in 1985, with Rosemary Harris starring; she won the best actress Tony Award for her portrayal of a British neighbor of the Cohens/Krogers.

Based on her long-term friendship with Doel, mostly via letters, she had earlier written and published 84 Charing Cross Road (1970), which was a bestseller.