Tesla's papers

Nikola Tesla died alone in Room 3327 in January 1943, and within days the government had taken his trunks.

Tesla's Room 3327 and the Trunks the Government Took

When Nikola Tesla died in his New York hotel room in January 1943, the Office of Alien Property seized his belongings, at the FBI's request by Wikipedia's account, though he was a naturalized citizen. An MIT engineer, John G. Trump, examined the papers and found nothing dangerous; they went to Belgrade in the 1950s. Accounts of missing papers have followed ever since. Here are the FBI's own records, what was taken and what is still unaccounted for.
From Signals

Tesla's Colorado Springs Receiver and a Signal That Counted

In 1899 Nikola Tesla ran an experimental station at Colorado Springs, where his receivers picked up electrical disturbances he could not trace to the Sun, the aurora or the Earth. He told the Red Cross and Collier's Weekly that he might have heard one planet greeting another. Here are his own words, the station, the explanations proposed since, among them Marconi and Jupiter, and what is still unsettled.