As a mushroom cloud illuminated the sky over the top-secret Trinity test site in New Mexico, an engineer named Oscar Seborer was part of a United States Army unit monitoring seismological activity at the site.
This first successful detonation of a nuclear weapon capped off two years of Manhattan Project work at Los Alamos, and laid the groundwork for the bombs that devastated Hiroshima and Nagasaki and effectively won World War II for the Allies.
But, it turns out, Seborer was not merely a technician and has recently been named as a fourth Soviet spy at Los Alamos in a recent paper, joining Klaus Fuchs, Theodore Hall, and David Greenglass in an alleged espionage ring. And while there is no established link between the spy rings, Greenglass’ sister was notably the ill-famed Ethel Rosenberg, who was executed along with her husband Julius Rosenberg in 1951, after a controversial espionage trial.
The paper, “Project SOLO and the Seborers: On the Trail of a Fourth Soviet Spy at Los Alamos,” was written by Harvey Klehr and John Earl Haynes for Studies in Intelligence — a publication of the CIA’s Center for the Study of Intelligence. (The report does not represent US government endorsement or official acceptance of the findings.)
The son of Polish Jewish immigrants, Seborer worked at Los Alamos from 1944 to 1946. In less than a decade, amid US tensions over Soviet espionage, he would leave America for the USSR, where he lived until his death in 2015.