What drew you to Hoover?
How incredibly mysterious he was. The more I researched, the more intrigued I became. I don’t think you could ever know everything about him, but I felt I understood what drove him.

Which was what?
His mother. She was this really intense stage mom who wanted her son to have great glory. He lived with her until he was 40 years old; his father wasn’t present in a major way and was mentally ill toward the end of his life — I think he was manic depressive and unable to really function. Even when Hoover was under great criticism, she was always there to be his guiding force.

Who gave you the most insight into Hoover?

The only remaining man that worked with him, [former FBI deputy director] Deke DeLoach. I spent a day with him. I wanted to know what kind of personality [Hoover] had on a social level, how he held his hands, how he would fly at people, how he conducted his work at the office — all those minute details that only somebody who knew him for a long time could answer.

Did you reach any conclusions about his sexuality?

No one knows the answer. What this film is trying to portray is that, whatever he felt, he was not able to live out his personal life in a way that allowed him to love and be loved. But what you cannot doubt is that Clyde Tolson and he had a relationship that spanned most of their life; they lived with each other, had lunch and dinner, and [Hoover] left everything to Clyde. Unarguably, they were partners in some sense.

Source: HR