FBI wiretaps have "given us the most powerful and persuasive source of all for seeing how utterly selfless Martin Luther King was," as a civil rights leader, according to a leading civil rights scholar.

"You see him being intensely self-critical. King really and truly believed that he was there to be of service to others. This was not a man with any egomaniacal joy of being a famous person, or being a leader," said Pulitzer Prize-winning scholar David Garrow in a recent interview with CNN.

Hoping to prove the Rev. Martin Luther King Jr. was under the influence of Communists, the FBI kept the civil rights leader under constant surveillance.

The agency's hidden tape recorders turned up almost nothing about communism.

But they did reveal embarrassing details about King's sex life -- details the FBI was able to use against him.