Hoover once wrote Mencken to compliment an article entitled, "Reflections on Homicide," ("Your keen analysis of this topic indicates a clear understanding of this particular phase of crime, and I am sure that your readers enjoyed your discussion.") and offered him a tour of the bureau's facilities. Later, when Mencken was writing a book on speech and language, he wrote to Hoover personally to inquire about the origins of the term, "G-Men," referring to federal agents.See the full article from The Baltimore Sun here: Baltimore Crime Beat: Mencken and Hoover - baltimoresun.com
Here's Mencken's letter
Feb 10, 1944:
- "I am engaged at the moment upon a somewhat elaborate supplement to my old book, "The American Language." and I get into it a great deal of accumulated material about words and speechways that have arisen since my last edition. In particular, I'd like to have a really accurate note on G-man. Do you happen to know where and by whom it was invented, and at what time precisely? Also what is its derivation and is it used officially? My most abject apologies for bothering a busy man with such questions."
Hoover wrote back, describing how G-man stood for "government man" and was apparently first uttered by fugitive "Machine Gun" Kelly during his apprehension in Tennessee. "If you will recall the case, Machine Gun Kelly made numerous boasts that he would never be taken alive and that whoever apprehended him would find it rather difficult facing his machine gun," Hoover wrote. He said that when agents rushed in to take Kelly into custody, they expected gunfire but instead found Kelly standing in the corner with his hands in the air saying, "Don't shoot, G-man!"
vault of documents released to the public includes a file of documents on famous Union Square resident and legendary Sun journalist H. L. Mencken, who apparently traded letters with FBI Director J. Edgar Hoover.