While the vast majority of letters, interviews and other data gathered by the FBI regarding Richard Feynman paint the picture of a loyal genius who helped the United States of America build the first atomic weaponry, one interviewee saw a more sinister purpose: A methodical, patient path towards betraying the country from its very highest ranks.

The FBI’s tipster, who offered to “swear to these things on a Bible, in a court, or before President Eisenhower”, wrote:

And indeed, the letter’s author (whose name has been redacted) laid out an interesting case for Feynman-as-secret-agent, citing his analytical mind, film-developing prowess, code breaking techniques and his well-known fascination for lock picking. The latter was a skill he regularly showed off at Los Alamos, to the chagrin of more security-minded scientists.

The letter also warned of Feynman’s “unusual personal magnetism.”

Perhaps that skill worked its magic on the FBI itself: The records don’t indicate that the Bureau, despite its extensive investigations into Feynman, took the letter very seriously.

Read the full letter embedded below, or on the request page.

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