WASHINGTON - Legendary FBI Director J. Edgar Hoover spent decades investigating Frank Sinatra and his possible ties to organized crime, but that didn't stop Ol' Blue Eyes from mourning Hoover's death and recommending a friend to replace him. The National Archives this week released more than 10,000 documents from Richard Nixon's presidency, including one letter indicating the Hoboken-born crooner urged Nixon to fill the FBI vacancy with Los Angeles County Sheriff Peter Pitchess, a former FBI agent and associate of Sinatra's. "This is just a note to tell you how much I appreciated your telegram about the passing of J. Edgar Hoover. His death is, indeed, a great loss to our nation," Nixon wrote to Sinatra in a letter dated May 10, 1972. "As you may know, I have decided to defer nominating a permanent successor to Director Hoover until after the forthcoming national election to insure that the Bureau retains its vital non-partisan character," Nixon wrote. "However, I do welcome receiving the names of possible candidates for the Directorship, and your thoughtfulness in suggesting Sheriff Pitchess is especially appreciated. You may be assured we will keep your recommendation in mind." The Watergate break-in occurred about a month later, and Nixon, soon to be consumed by the scandal that would bring down his presidency in 1974, selected loyalist L. Patrick Gray as acting director. Gray was nominated in 1973 as permanent director, but the nomination was withdrawn after he admitted to destroying documents given to him by White House Counsel John Dean. Nine years later, Pitchess publicly testified as a character witness for Sinatra when the singer was seeking a Nevada casino license. The sheriff told the gaming board he had investigated Sinatra and found no ties to the mob, asserting, "If Mr. Sinatra is a member of the Mafia, then I am the Godfather." In 1998, the FBI released its 1,275-page file on Sinatra, showing the bureau had investigated dozens of rumors and claims dating back to 1938, just as the singer's career was taking off. Many of the allegations dealt with Sinatra's alleged mob ties.