I have a letter Hoover sent to my grandfather, who was an attorney, that is dated May 1, 1972 - the day before Hoover's death from a heart attack.
I am interested generally in connecting with a Hoover expert to discuss the historical context and significance of the letter, which I realize must surely have been only one of dozens of letters and other documents Hoover would have signed that day.
That said, the lore in my family for all these years has been that this may be the "last document Hoover ever signed". I am interested in how I might go about finding evidence for or against this fact.
Thanks for any and all input and advice!
Identifying the last document he signed seems like a question for an archivist rather than a Hoover expert. I believe the biggest collection of J Edgar Hoover’s papers is at the National Archives in College Park, Maryland. If I were you I would go to their website and either get in contact with an archivist there directly, or use their inquiry submission function to ask about the last of his signed papers. They may also be able to direct you to other collections of Hoover’s letters.
As for talking with an expert about the context and significance of the letter, I would try to get in touch with someone who has written a biography of Hoover (like Anthony Summers) or someone who has written a book focused on him. These people will have the most knowledge about his life and letters.