Photo Credit: Public domain via Wikimedia
Julius and Ethel Rosenberg

Oscar Seborer, who was working at Los Alamos, NM, at the time Manhattan project scientists were laboring to beat their Nazi counterparts in the race for an atomic weapon, passed sensitive information to Soviet agents, according to an article titled “On the Trail of a Fourth Soviet Spy at Los Alamos” by Harvey Klehr and John Earl Haynes, in the current issue of the CIA journal Studies in Intelligence.

The report reads like a John le Carré novel written in collaboration with Shalom Aleichem. Here are a few amazing excerpts – we highly recommend you download the PDF file and spend the rest of your Sunday hovering over it with a nice cup of tea. We are grateful to the Central Intelligence Agency for making this fascinating story available.


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Like many Jewish families from Eastern Europe, the Seborers came to the United States in stages. Abraham, born in 1876, and Jennie, born in 1881, left Poland with their eldest son, Max, born in 1903. They traveled to Great Britain, where another son, Noah, was born in 1905. Stuart, born as Solomon, came along in 1918. By the time their only daughter, Rose, was born in 1919, the family had been living in the United States for a decade. The youngest child, Oscar, followed in 1921.

Max and Noah both attended Cornell University on scholarships, and Oscar and Stuart went to City College of New York. Stuart also won a New York State scholarship and enrolled in the ROTC program. Abraham and Jennie lived in Palestine from 1934 to 1938 before moving back to New York. Oscar apparently went with them, but Stuart, enrolled at CCNY, stayed in the United States and may have lived with Max.

City College was a hotbed of communist activism when two of the Seborers sons attended. / CUNY Academic Works Collection

All of the children gravitated toward the Communist Party USA (CPUSA). In fact, the Seborer family was part of a network of people connected to Soviet intelligence. Max was brought into the communist movement by his Cornell friend Gibby Needleman. He was a teacher for a number of years before going to work for Needleman’s law firm. His first wife’s sister, Rose Biegel Arenal, was married to Luis Arenal, implicated in the KGB plot to kill Leon Trotsky.

Oscar enrolled at Ohio State to study electrical engineering but joined the Army in October 1942. In view of his engineering training, the Army assigned him to the Special Engineering Detachment that provided technically trained soldiers to fill a variety of specialist posts in the Manhattan Project. He worked at Oak Ridge before being transferred to Los Alamos in 1944 and remained there until 1946. He was present at Trinity site, near Alamagordo, as part of a unit monitoring seismological effects of the first explosion of an atomic bomb, as a technician fifth grade. It was not until after the war that Stuart and Oscar began to run afoul of security agencies.

After his discharge from the Army in 1946, Stuart became a civilian employee of the Army’s Civil Affairs Division, first as a research analyst and then as chief of the European Unit. His wife Miriam, meanwhile graduated from George Washington University Medical School in 1950.

In January 1949 an Army memo recommended that he be fired because of communist associations. There was conflicting information in the report and Gen. Leland Eberle ordered that he be interviewed. In June, Eberle dropped the proceedings, noting that Stuart’s affidavit had answered the charges, sources who knew him vouched for him, and all the accusations were anonymous. At his loyalty hearing Stuart had been indignant. He denied knowing of his brothers’ and sister’s communist ties, insisting that he had had little contact with them for years and that he should not be tarred by their beliefs. He declared: “I resent it being said that I have ever had any connection, or implied connection with the Communist Party or any other subversive organization. I am vigorously and emphatically opposed to communists and communism.”

Although he was being considered for a job at the State Department in 1950, Stuart was informed in mid-August that he would not be granted a security clearance. Oscar applied for a civilian position at Los Alamos on 28 May 1947 but withdrew his application just one month later for unknown reasons. He then resumed the engineering studies that had been interrupted by the war. He attended the University of Michigan from September 1947 to August 1948 and received his master’s degree in electrical engineering.

He then was hired at the US Navy’s Underwater Sound Laboratory in New London, Connecticut, the center for naval research on sonar for ships and submarines. In August 1949, the commanding officer recommended removing him as security risk. Three weeks later, on 29 August, a Loyalty Review Board overturned the decision and asked for further investigation.

At the end of April 1950, the lab decided he could be retained, but Oscar transferred to the Electronic Shore Division of the Navy’s Bureau of Ships in Washington. At his new job he was involved with planning the installation and supervision of electronic equipment in American and European harbors. The only man in the unit without a security clearance, he was “a marked man” and resigned his position on 1 June 1951.

The Seborer brothers’ problems with getting security clearances coincided with a growing concern about espionage. Following the Soviets’ atomic bomb test in 1949, Klaus Fuchs was arrested in Great Britain in February 1950 and confessed to spying while he was at Los Alamos. Three months later Harry Gold, his courier, was arrested, and he led the FBI to David Greenglass in June. By July, Julius Rosenberg was in custody. By the time the Rosenbergs and Morton Sobell went on trial in 1951, many of their friends from CCNY’s communist movement were under suspicion and one, William Perl, had been convicted of perjury. Several others, including Joel Barr and Alfred Sarant, had vanished. Decades later Barr and Sarant were identified as living in the USSR under assumed names.

Stuart and Oscar Seborer also decided it would be prudent to leave the United States. Together with Miriam and her mother, Anna, they booked passage on the SS Liberte, bound for Plymouth and LeHavre, on 15 February 1951 and sailed on 3 July. The long delay between purchasing the tickets and actually leaving indicates that they were not fleeing some kind of fear of imminent danger—unlike Morris and Leona Cohen, two Soviet agents, who vanished from their New York apartment suddenly in June 1950.

The Rosenbergs had been sentenced to death in April 1951, and the hunt was on for other spies, but neither Seborer brother was in the crosshairs of any espionage investigation. They had become identified as security risks because of their association with communists, but indications of possible espionage had not surfaced in their security reviews. In fact, the first indication the FBI or any other security agency received of their involvement with Soviet espionage was Needleman’s conversation with Jack Childs in 1954.

The FBI quickly learned that Stuart had continued to receive veteran’s disability checks for several years after he left for Europe. For a while, they went to Max’s address. Until February 1952, they had been cashed in Europe, so he had obviously forwarded them. Thereafter, checks allegedly signed by Stuart and countersigned by Max were deposited in Max’s bank account. In a letter to the Veteran’s Administration, Max was listed as having power of attorney, although no such authority seemed to exist. That, and his 1951 trip to Israel, suggested that Max was in collusion with his brothers.

The FBI faced an excruciating dilemma in trying to untangle the Seborer case. While the full extent of its investigation awaits further FOIA releases, it was constrained by the fear that too vigorous a pursuit of this spy ring might cause Needleman to suspect Jack Childs, its chief source, and endanger Operation SOLO, its premier counterintelligence operation providing vital information about both the CPUSA and the international communist movement.

The chief suspects, apart from Needleman, were beyond the FBI’s reach, in the USSR by the time it learned what they had done. Even after Miriam Seborer returned from the USSR in 1969, SOLO was active and the FBI had no independent evidence with which to pressure her. So, the Seborer brothers—and particularly Oscar—got away with espionage.

Jack Childs died in 1980; in 1982, Morris went into the government’s witness protection program. By that time, Gibby Needleman had died (1975). Max Seborer died in 1978. After her return from Moscow, Miriam Seborer worked as a medical technician and then was acting medical director of the United Nations Medical Service before resigning in February 1974 in protest against not being considered to be permanent director. She later worked as medical director for an insurance company. In 1996 she was placed in a nursing home; she died in 2002.

Oscar Seborer died on 23 April 2015 in Moscow. Among the attendees at the funeral was a representative of the FSB, the Russian internal security service. His brother Stuart was present in a wheelchair. A friend explained that “both brothers are communists—they maintained their convictions and language.” And both lived to see the cause for which they had betrayed their native land disintegrate. Although a Moscow apartment and phone number for Stuart Smith still were listed in 2018, no one answered the telephone or the doorbell.


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