Susan Rosenstiel will never forget her first glimpse of "Mary" Hoover—and neither will readers of Anthony Summers' controversial new best-seller, Official and Confidential: The Secret Life of J. Edgar Hoover, in which her description appears. Entering a suite in New York City's Plaza Hotel in 1958 with her then husband. Mob-connected Schenley liquor magnate Lewis Rosenstiel, she says she saw a figure "wearing a fluffy black dress...lace stockings and high heels, and a black curly wig. He had makeup on, "she recalled. "Roy [Cohn] introduced him to me as 'Mary' and he replied, 'Good evening,'—brusque.... It was Hoover."

Rosenstiel's is but one of many startling claims unearthed by Summers, an Irish former BBC correspondent, and his research team, who conducted more than 800 interviews and combed thousands of previously unpublished FBI and Justice Department documents to piece together the private life of the man who enjoyed absolute power as head of the FBI for 48 Years. The resulting book has "the sticky patina of sensationalism," wrote New York Times reviewer Christopher Lehmann-Haupt. And there's no doubt that Summers has drawn the most scandalous conclusions from the material. Yet as Lehmann-Haupt goes on to note, the work is "overwhelming in its detail and extensiveness...an impressive swamp of negativity."

The flood of documents forced Summers, 50, to add on lo the stone house in County Waterford, Ireland, he shares with third wife Robbyn Swan, 30, an American journalist he hired for the Hoover project in 1988. They married last June.

An Oxford-educated hoteliers' son, Summers has written four previous books including Goddess, a best-selling biography of Marilyn Monroe. "Living with J. Edgar Hoover for five years is something I wouldn't recommend to anyone," Summers recently told senior writer Pam Lambert. "He was such a sad, dull man."

Since his death in l972 there have been severed books about Hoover. What's new in yours?

A series of interviewees told me that top mobsters, in particular Meyer Lansky, were able to force Hoover into ignoring organized crime for almost 30 years because of compromising photographs they had of him in homosexual activity with Clyde Tolson [Hoover's longtime FBI aide]. This could explain why Hoover took a hands-off attitude toward organized crime and denied it even existed.

Also, my book finally confirms long-standing rumors that Hoover was homosexual. And it contains new information on the extent to which Hoover used his secret files to manipulate politicians. John F. Kennedy's personal secretary, Evelyn Lincoln, reveals how her boss was forced to accept Lyndon Johnson as his running mate because of information on Kennedy's womanizing led to Johnson by Hoover.

Hour could Hoover have been careless enough to be blackmailed?

We learn time and again that public men who know they can be destroyed by their sexual peccadilloes nevertheless indulge them. I think eventually Hoover came to believe in the myth he had created about himself—that he was untouchable.

Why delve so deeply into Hoover's sex life?

Hoovers sexuality impinged on his ability to function properly as director of the FBI. If indeed Mob leaders were able to neutralize Hoover because of his homosexuality then the case can be made that his sex life helped make possible the existence of the Mafia as we know it.

How credible are the allegations of transvestism?

When Susan Rosenstiel first told me about seeing Houver in drag I almost wished that she hadn't, because it seemed so incongruous and so completely extraordinary. But people who had heard her testimony in 1970 before the New York State Crime Commission concerning her ex-husband's Mob ties gave her credibility the highest marks. And then I found two other individuals with no connection to her.... It was chilling when they described the Hoover photographs they had seen, because they had him wearing the same type of women's clothing old-fashioned flouncy dresses and so on—she described.

What was the relationship between Hoover and Tolson?

It seemed rather like many marriages: a fairly passionate relationship—to the extent Hoover was capable of passion—in the beginning, but perhaps less and less active on the physical side as time went on. But what Hoover needed, and what he had in Tolson, was somebody who was absolutely, totally reliable.

How corrupt was Hoover?

John Dowd, the attorney who led that Justice Department probe into the misuse of FBI funds after Hoover's death, called Hoover's the worst abuse of office by a public servant that he had ever come across. For example, Hoover profited from investment tips from people he should have been investigating. He got "no-lose" tips from crime-linked oil barons like Clint Murchison and Sid Richardson.

So how was he able to survive through eight administrations?

It's more complex than Hoover's ability to pressure Presidents with dirt he dug up. Hoover used his massive propaganda department to build himself up into a national icon. You don't just fire an icon. More important, he encouraged Presidents to use the FBI for often illegal political snooping—and by doing so, they delivered themselves into his hands. Hoover functioned as an "intelligence valet" for every President from Roosevelt to Nixon.

What was the worst thing Hoover did?

This hypocrite ruled through the use of propaganda and fear for half a century while constantly trumpeting American civil liberties. It's also the fact that he was allowed to continue even though people in government had to know the extent to which he was abusing his office.

Is there anything good to say about Hoover?

The kindest thing one can say about him is that, professionally, Hoover created a bureau from virtually nothing, from a ramshackle little thing with a lot of corruption. He hired [qualified] agents, trained them properly and above all brought science to law enforcement. But someone else could have done that job. It doesn't take a Mussolini to make the trains run on time.