Tim Weiner's new book "Enemies: A History of the FBI" traces the history of the FBI's secret intelligence operations, from the bureau's creation in the early 20th century through its ongoing fight in the current war on terrorism.

The author speaks to Fresh Air's Terry Gross about FBI Director J. Edgar Hoover's legacy, his list of gays in government and his relationship with President Nixon.

On J. Edgar Hoover's legacy

"Hoover is the inventor of the modern American national security state. Every fingerprint file, every DNA record, every iris recorded through biometrics, every government dossier on every citizen and alien in this country owes its life to him. We live in his shadow, though he's been gone for 40 years. As they always told the agents at the FBI academy when they were training, 'An institution is the length and shadow of a man.' "

On Robert Kennedy authorizing Hoover's plan to bug Martin Luther King Jr.

"Hoover had come to Bobby Kennedy and President Kennedy and said, 'Look, Stanley Levinson - King's adviser - is a communist. He's a secret communist, he's an underground communist, and he's using Martin Luther King as a cat's paw.' Well, when you put it that way, you weren't gainsaying Hoover if you were John or Bobby Kennedy. So they said yes."

On why Hoover asked Roosevelt for "unlimited powers"

"Hoover did not want any limits. He wanted no charter, no rules. He wanted the FBI to investigate the so-and-so's. And he believed that the Soviet Union was trying to steal America's atomic secrets, to burrow into the State Department, the Pentagon, the FBI and the White House - and he was right."

On Hoover's list of gays in government

"Hoover's war on gays in the government dates back to 1937 and lasted all his life. He conflated - and he was not alone - communism with homosexuality. Both communists and homosexuals had secret coded language that they spoke to each other, and they had clandestine lives, they met in clandestine places, they had secrets. And in certain cases, such as the British spy ring that penetrated the Pentagon in the 1940s and early 1950s, they were both communists and homosexuals. Hoover didn't see a dime's worth of difference there. They were one and the same. This was hammered into him when the FBI dealt with one of the most famous informants - Whittaker Chambers - who helped bring down secret Soviet espionage rings in this country. He was a well-known writer at Time magazine. Chambers was a secret homosexual and a secret communist. Hoover saw a nexus there, and he never let that thought go."

On Hoover's relationship with President Nixon

"It was deep. It was based on mutual respect and dependency. And then it broke down during the last year and a half of Hoover's life - around the time that Nixon turns on the White House tapes and starts bugging himself. Nixon wants his enemies destroyed - all of them. Hoover is no longer willing to do his dirty work for him - his black bag jobs, his breaking and entering, his bugging. Nixon becomes increasingly frustrated with this and he sets up his own bucket shop - the plumbers. Six weeks after Hoover dies, they get caught breaking into the Watergate."