J. Edgar Hoover hated Armie Hammer's 'spy' grandfather

Actor Armie Hammer is still stunned by his casting as J. Edgar Hoover's longtime companion in Clint Eastwood's new biopic - because the FBI boss and his great grandfather hated one another.

Tycoon Armand Hammer became a person of great interest for Hoover and his federal agents because of his ties to the former Soviet Union and his business friendships with several Russian officials, and his great grandson insists Hoover hated the old man.

But, in a weird twist, The Social Network star plays Clyde Tolson opposite Leonardo DiCaprio's Hoover in the new biopic.

The actor says, "My great grandfather all the way up through the Cold War, he was a private U.S. citizen who could fly between the United States and Russia... as much as he wanted just because of the connections he had, so Hoover immediately was like, 'Spy! Definitely a spy!'"

And Armie Hammer's grandson thinks the FBI might have been onto something: "I wouldn't put it past him... He might have been (a spy)."

And the script for Clint Eastwood's film brought back a few sinister childhood memories for Armie Hammer: "I remember stories as a kid of like, 'They went through the trash,' or, 'They listened on the phone...' and I can remember thinking, like, 'You guys might be full of yourself...' But then I read the script and I was like, 'Holy c**p, this is all true... Maybe this did happen.'"