From PBS.org:

The Missing Papers One of the more controversial topics involving Nikola Tesla is what became of many of his technical and scientific papers after he died in 1943. Just before his death at the height of World War II, he claimed that he had perfected his so-called “death beam.” So it was natural that the FBI and other U.S. Government agencies would be interested in any scientific ideas involving weaponry. Some were concerned that Tesla’s papers might fall into the hands of the Axis powers or the Soviets. The morning after the inventor’s death, his nephew Sava Kosanovic´ hurried to his uncle’s room at the Hotel New Yorker. He was an up-and-coming Yugoslav official with suspected connections to the communist party in his country. By the time he arrived, Tesla’s body had already been removed, and Kosanovic suspected that someone had already gone through his uncle’s effects. Technical papers were missing as well as a black notebook he knew Tesla kept—a notebook with several hundred pages, some of which were marked “Government.” P. E. Foxworth, assistant director of the New York FBI office, was called in to investigate. According to Foxworth, the government was “vitally interested” in preserving Tesla’s papers. Two days after Tesla’s death, representatives of the Office of Alien Property went to his room at the New Yorker Hotel and seized all his possessions.

This is a rather boringly bureaucratic way of putting it. The FBI was run by J. Edgar Hoover.

Dr. John G. Trump, an electrical engineer with the National Defense Research Committee of the Office of Scientific Research and Development, was called in to analyze the Tesla papers in OAP custody. Following a three-day investigation, Dr. Trump concluded: His [Tesla’s] thoughts and efforts during at least the past 15 years were primarily of a speculative, philosophical, and somewhat promotional character often concerned with the production and wireless transmission of power; but did not include new, sound, workable principles or methods for realizing such results.

Or so Dr. Trump said …

Where have we heard that name before?

From Wikipedia:

John George Trump (August 21, 1907 – February 21, 1985) was an American electrical engineer, inventor, and physicist. A professor at the Massachusetts Institute of Technology from 1936 to 1973, he was a recipient of U.S. President Ronald Reagan’s National Medal of Science and a member of the National Academy of Engineering.[3][4][5] John Trump was noted for developing rotational radiation therapy.[3] Together with Robert J. Van de Graaff, he developed one of the first million-volt X-ray generators. He was the paternal uncle of Donald Trump, who would later go on to become the 45th president of the United States.

I don’t really like comic books, but I like history that sounds like a comic book. That J. Edgar Hoover sent Donald Trump’s uncle to investigate Nikola Tesla’s secret papers sounds like the plot for a Captain America movie.