J. Edgar Hoover, America's revered and feared controversial top cop for five decades, was one of the most secretive men in government, keeping covert files on powerful figures including President John F. Kennedy and Martin Luther King Jr.

But now the tables are being turned on the man who helped create the Federal Bureau of Investigation (FBI) 75 years ago as movie J. Edgar opens in U.S. theaters on Wednesday with an all-star cast and crew.

I see it as a love story, a tragic love story, and that was a big part of the appeal of doing it, said director Clint Eastwood.

Written by Milk Oscar-winner Dustin Lance Black and starring Leonardo DiCaprio, the film addresses long-standing speculation that Hoover -- who never married -- was secretly gay and had an intimate relationship with his longtime assistant Clyde Tolson, played by Armie Hammer (The Social Network).

The two of them had lunch and dinner together every day, they socialized and even vacationed together, said Eastwood. As for anything else, I leave that up to the audience to decide.

J. Edgar traces Hoover's life from childhood to his death in 1972, and hits all the big historical highlights -- Prohibition, the Lindbergh kidnapping, World War II, 1950s Communists, the civil rights era and the assassinations of King, Kennedy and his brother Robert F. Kennedy. Hoover personally directed the FBI's investigation into the U.S. president's killing in 1963.

But it's his private life and the few key figures in it, including his domineering mother, played by Judi Dench, and Helen Gandy, his faithful secretary for 54 years, played by Naomi Watts, that intrigued Eastwood the most.

We never knew too much about Tolson, Gandy or any of his close confidants but (what we learned) through researching this movie, Eastwood said. That's what's fun about making a movie, you get to learn something about people.

HERO OR VILLAIN?

As an FBI agent who liked the limelight when it came to arresting gangsters, DiCaprio's Hoover gets to point pistols and act tough.

But the actor also engages in a homoerotic wrestling match with Hammer and kisses his co-star. In the film's most bizarre and moving scene, he wears his mother's dress after her death.

It was an important scene and it was done sensitively. It shows another side of a very complex character, said DiCaprio. He was a Crock Pot of eccentricities...He lived with his mother until he was forty years-old. He listened to his mother for political advice.

He was this incredibly ambitious young genius that really transformed our country and created this federal bureau that's revered and feared. Yet he was a momma's boy and he was incredibly repressed emotionally, DiCaprio added.

Eastwood, 81, said he grew up in the 1940s and 1950s with his own impressions of Hoover as a heroic figure. But that was well before the information age.

We didn't know about Hoover except for what was usually in the papers. So, it was fun to delve into a character that you'd heard about all your life, but that you never really knew and try to sort that out, the Oscar-winning director said.

DiCaprio said that whatever Hoover's sexual orientation he was devoted to his job, and power was paramount to him. Holding onto that power at all costs was the most important thing in his life.

He's an enigma, summed up Eastwood. We'll never know the whole truth about him.