The Tesla FBI files: seizure, secrecy, and the papers that disappeared

The FBI's interest in Tesla began not with a threat assessment or a counterintelligence operation but with a newspaper clipping. In September 1940, a private citizen mailed J. Edgar Hoover a New York Times interview in which Tesla described a device he called the teleforce, which the press had taken to calling the Death Ray. Tesla, then in his mid-eighties and largely destitute, had been trying for years to interest the War Department in the weapon. The letter-writer's concern was plain: if these plans fell into enemy hands, the consequences could be catastrophic.

Hoover's written response was brief and dismissive. The file stayed open but largely dormant for the next three years. A handful of inter-agency communications accumulated, debating whether Tesla's claimed weapon was credible. The official consensus: Tesla was elderly, broke, and living in a hotel room. The teleforce was theoretical at best.

What none of the correspondents knew was that Tesla had recently told at least one person a different story.

In December 1942, approximately one month before his death, Tesla met with Bloyce Fitzgerald, an engineer who had worked with him on various projects. According to a statement Fitzgerald later gave to a government official that appears in the released FBI documents, Tesla told him at that meeting that his wireless power transmission and particle beam experiments had been completed and perfected. Not in progress. Not theoretical. Completed and perfected.

Fitzgerald's account was not given much weight at the time. Tesla had a long and well-documented history of dramatic claims about inventions that proved impossible to independently verify. The scientific establishment had largely written him off. Whether Fitzgerald's account reflects a genuine technical development, an elderly inventor's final claim to a trusted friend, or something in between is a question the declassified record does not resolve.

Tesla was found dead in Room 3327 of the Hotel New Yorker. Hotel records initially listed the date as January 7. A subsequent inquiry documented in the FBI files established that he had actually died on January 8. The correction matters because it tightens the timeline of what happened next: within hours of the confirmation of his death, agents from the Office of Alien Property Custodian were at the hotel.

The OAP's authority derived from the Trading with the Enemy Act and related wartime statutes. Its mandate was property belonging to foreign nationals. Nikola Tesla had been a naturalized American citizen since 1891. A letter dated January 12, 1943, in the released FBI documents, explicitly acknowledges this: the OAP might not have jurisdiction over Tesla's property because he was a citizen, but the agency expressed confidence it could keep the material secured against any other interested party for at least two days while the jurisdictional question was resolved.

It was not resolved. The material was taken anyway. Two truckloads of trunks, notebooks, drawings, correspondence, and apparatus were removed from the Hotel New Yorker and transported to a Manhattan storage warehouse under FBI direction. No inventory was made available to Tesla's family or his designated executor. The seizure of a naturalized citizen's papers, without established legal authority, within hours of his death, is confirmed in the government's own memos.

A memorandum dated January 9, 1943, states directly that Tesla had performed many experiments in connection with the wireless transmission of electrical power, commonly called the death ray. The Bureau was simultaneously concerned about Tesla's nephew Sava Kosanovic, a Yugoslav diplomat with ties to the Tito government. The FBI file describes Kosanovic as someone Tesla intensely disliked and expresses concern that he had been attempting to gain possession of Tesla's papers and would, if successful, make such information available to the enemy. The Bureau recommended constant guarding of the material.

There was also a specific rumor the government took seriously enough to investigate directly: Tesla had a working prototype of the teleforce device, or at least a critical component, locked in a box at the Governor Clinton Hotel. This was treated as credible enough that John G. Trump, the MIT engineer called in to review the seized papers, was specifically sent to open the box and examine its contents.

Trump opened the box. Inside was a piece of electrical testing apparatus several decades old. Not a weapon. Not a prototype. Standard high-voltage testing equipment from an earlier period of Tesla's work that he had apparently kept for years.

John G. Trump was a distinguished high-voltage physicist at MIT, a member of the National Defense Research Committee of the Office of Scientific Research and Development, and a collaborator of Robert J. Van de Graaff who had also contributed to Allied radar research. He was also, though not widely known at the time, the uncle of Donald Trump. In January 1943 he was among the most qualified people in the country to assess whether Tesla's technical papers constituted a national security concern.

He spent three days on the evaluation. His conclusion, referenced in subsequent FBI documents, was that the papers contained nothing of significant value and did not constitute a hazard in unfriendly hands. He specifically addressed Tesla's particle beam papers: the plans did not contain sufficient technical information to construct a working device, and any configuration that could actually be built from the described specifications would be of very limited power.

Here is what the public record does not contain: Trump's actual report. References to his findings appear throughout subsequent FBI memos, but the full text of his formal written assessment has not been released as a standalone document in any of the FBI's FOIA publications. What is known about his conclusions comes entirely from how later documents describe them. The report itself remains unreleased. This is a documented gap.

After Trump's review, the papers were formally released from OAP custody. They did not reach Tesla's family. The New York State Department of Taxation held an outstanding claim against Tesla's estate for substantial unpaid back taxes, and the papers were immediately seized a second time by state tax authorities and placed in additional storage. This second seizure is documented in the record but far less discussed than the first.

While the papers were in tax custody and before any public accounting had been made, the 1944 biography "Prodigal Genius: The Life of Nikola Tesla" by John J. O'Neill claimed the FBI had retained Tesla's most dangerous inventions as a matter of national security. Hoover began receiving letters demanding the papers be released. He denied FBI possession in personal responses for the next three decades. In 1953, the Bureau traced the source of the ongoing correspondence campaign to O'Neill's book, then nine years in circulation. Hoover decided against seeking a public correction and continued answering the letters individually as they arrived for the rest of his life.

In 1951, an American court declared Sava Kosanovic, the Yugoslav nephew the FBI had been monitoring as a security risk for eight years, to be the rightful heir to Tesla's estate. Approximately sixty trunks of papers, equipment, and personal effects were transferred to Belgrade in 1952 and now reside at the Nikola Tesla Museum. Whether the Belgrade transfer represents a complete accounting of what was seized at the Hotel New Yorker in January 1943 has never been confirmed in any publicly available document. Tesla's Edison Medal, awarded in 1916 by the American Institute of Electrical Engineers and present in his hotel room at the time of his death, does not appear in the Belgrade collection. It has not been located.

The FBI released an initial set of Tesla-related documents in September 2016 in response to accumulated FOIA requests. A follow-up release of 64 additional pages followed in March 2018, including a catalog of Tesla's writings as evaluated by the OAPC. The combined release totals approximately 290 pages. Portions remain redacted under national security and privacy exemptions. The Bureau has not publicly stated whether additional pages exist.

What the releases confirm: the FBI was genuinely concerned about Tesla's work from 1940 onward; the OAP seizure proceeded with internal awareness of its legal vulnerability; the official finding was that nothing of military value was present; Hoover personally denied Bureau involvement in the papers for decades while maintaining an active file; and the thirty-year campaign to recover supposed suppressed weapons files was, according to the Bureau's own position, built on a single unverified biographical claim from 1944.

What the releases do not resolve: whether the Belgrade transfer in 1952 was complete; what became of Tesla's Edison Medal; why certain pages in the 2016 and 2018 releases remain redacted; and what the full text of John G. Trump's formal three-day evaluation report actually says.

The January 9, 1943 death-ray memorandum. The January 12, 1943 seizure letter acknowledging questionable jurisdiction. The Bloyce Fitzgerald statement on Tesla's final claims. The Kosanovic surveillance record. The Hoover denial letters spanning three decades. Transcribed from the FBI Vault 2016 and 2018 FOIA releases.