In nearly 30 years as a magazine journalist, Ron Rosenbaum has made something of a specialty of sketching whole universes of obsession in 10,000 to 15,000 words. Whether descending into manholes in Dealy Plaza with JFK assassination buffs or walking the hills of Qumran with fiercely protective academic guardians of the Dead Sea Scrolls, untangling the thickets of CIA intelligence and counterintelligence or just riding shotgun with homicide detectives, Rosenbaum has mapped out the shifting territories of rational inquiry and irrational fixation -- making no secret of his own uncertain position somewhere in between.

Now, with his first full-length work of nonfiction, Rosenbaum has turned his attention to one of the most unsettled and unsettling mysteries of our time: the origins of Adolf Hitler's murderous hatred of the Jews. Explaining Hitler, out from Random House, is a fascinating open-ended survey of the state of our knowledge. It's also a portrait gallery of the journalists, biographers, psychoanalysts, historians and others who have tried to get a grip on Hitler -- without quite shaking his grip on them.

As the continuing bitter controversy over Daniel Jonah Goldhagen's Hitler's Willing Executioners shows, the Holocaust is a subject that seems to generate less, not more, certainty as time passes. In Explaining Hitler, Rosenbaum zeroes in on the questions on which the explainers can't even agree to disagree. Was Hitler a true believer convinced of his own righteousness, or a cold-blooded hater who manipulated widespread anti-Semitic feeling simply to advance himself? Was he an eruption of demonic evil into history, or someone whose transformation from the haunted-looking baby pictured on the cover of Rosenbaum's book into a killer of babies can be accounted for in ordinary psychological terms?

"I think the baby pictures really crystallize the whole question," Rosenbaum tells PW on a recent Saturday afternoon in the deserted library of New York City's Yale Club, somewhere along the shelves between Fitzgerald and Pynchon. "How did an innocent child -- you can't really accuse Hitler of crimes at age two -- become a mass murderer? You look at the bullshit the Freudians have done" -- tracing Hitler's pathology to lack of mother love, or a missing testicle -- "and it's pretty pathetic. But on the other hand, here's the child, here's the mass murderer, and there's this gap-this abyss, really-between them." He pauses. "Does that make any sense?"

For Rosenbaum, an intense, soft-spoken man with pale red hair and unruly matching eyebrows, the question isn't just a conversational tic. It's an indication of his cautious approach to the truth, the uncertainty principle behind the "personal odyssey" that took him from Paris to Munich to Jerusalem to the Gestapo Cottage, a memorabilia-filled inn near Hitler's alpine retreat where, in 1994, he spent a stereotypically dark and stormy night trying to get, as he puts it, "close to the Führer." The book begins with an untangling of the facts, half-facts and rumors that have surrounded this most image-conscious of dictators since he first appeared on the political scene. But it's also an impassioned meditation on the idea of evidence itself. "I'm torn between the view that there's just a lack of evidence -- that if we had the whole picture we would be able to explain Hitler -- and the view that no matter how much evidence we have, we still couldn't account for his evolution."

The Budding Enthusiast

For a man so present as a character in his own journalism, Rosenbaum is surprisingly uninterested in talking about himself. Born in 1946 in Manhattan to a purchasing agent father and a schoolteacher mother, he had what he insists was an "extremely unadventurous" childhood in Bayside, N.Y., on Long Island. In 1964, he enrolled at Yale. "I was a pretty intense English major," he recalls. "I lived most of my life in the 17th century or earlier, really." He stayed on for a brief stint as a graduate student but soon felt himself longing for a more adventurous life. "Journalism is a way for a shy person to overcome his inhibitions. I was very shy as a kid. I still am, actually. But if you have some goal, some mystery you want to solve, and some deadline you have to meet, then you have to talk to people and you have to go places."

Not that he checked his literary inclinations at the ivory tower's exit door. Whatever his subject, Rosenbaum writes with a goofy erudition that's equal parts gonzo and Gibbon. He is perhaps the only journalist to have talked about William Empson's Seven Types of Ambiguity with CIA counterintelligence chief James Angleton or the Pelagian heresy with Mario Cuomo. He's certainly the only one who could draw a squiggly but legible line between the Federalist Papers, death-row diva Karla Faye Tucker and Geraldo Rivera's new horn-rimmed glasses, as he did recently in "The Edgy Enthusiast," his weekly column for the New York Observer.

Since 1994, he has used the column to give vent to whatever seems to be obsessing him at the moment, whether it's his hatred of Seinfeld or a new mathematical refutation of Darwinian theory. Once, he turned the column into a 2000-word apartment want-ad on behalf of his tail-less cat, Stumpy, billed as the victim of a mob hit. It did the trick: the first call landed the pair their apartment in the Kip's Bay section of Manhattan.

It wasn't the first time Rosenbaum got lucky. In 1968, he was hired as a reporter at Long Island's Suffolk Sun, where his first assignment was shipping out to Chicago to cover the Democratic National Convention. But his real break came in 1969, when Dan Wolf, editor of the Village Voice, hired him as a staff writer. (That time, he found his apartment by walking around the Village wearing a sandwich board.) Rosenbaum went on to cover the 1969 anti-Vietnam War march, the McGovern campaign and eventually Watergate for the weekly. He was also picked up by another legendary '70s editor, Harold Hayes at Esquire. "I was lucky that I found people who encouraged my first fumbling efforts," Rosenbaum says. "I definitely couldn't have handled early rejection."

Rosenbaum resigned from the Voice in 1975 after new owner Clay Felker fired Wolf. The next year, High Times serialized his revenge farce of sorts, Murder at Elaine's, under the pseudonym George R. Boz. (The now-defunct Stonehill Press published the novel under Rosenbaum's name in 1978.) A dizzying send-up of New Journalism, conspiracy theories and investigative reporting, the novel featured a Rosenbaum-like writer who's obsessed with Dickens's unfinished novel, The Mystery of Edwin Drood, but gets caught up in real-life intrigue when a prominent publisher, said to resemble Felker, is found murdered in the famous literary watering hole of the title.

In 1979, Dell published a collection of his articles, Rebirth of the Salesman: Tales of the Song &Dance '70s. In the meantime, Rosenbaum continued his steady migration from newsprint to the glossy pages of Harper's, The New Republic and the short-lived Manhattan, inc., for whom he began an unlikely series of power-lunch profiles of the rich and famous.

Over the years, editors had often approached Rosenbaum about turning various articles into books. "I'd done a lot of satisfying pieces of long journalism," he says, "but I found that after several months, I'd somehow gotten to the bottom of the subject and exhausted my own interest."

Rosenbaum's long journey into the bottomless Hitler mystery began in 1982, when his father mentioned out of the blue a French cousin who had died in the Holocaust. "He had never ever said anything about it before," Rosenbaum recalls. Then there was a conversation about six months later with members of a militant Jewish organization in New York City who were plotting to kill Nazi war criminals living in America. "I got into an argument with them. One of them asked me, 'What if it were Weimar Germany. Wouldn't you think it was legitimate to assassinate Hitler?' And then I said something I've actually come to disagree with, which was that forces were so powerful that the Nazis still would've come to power."

In 1984, after coming across an article by Milton Himmelfarb called "No Hitler, No Holocaust," Rosenbaum started researching that contention, with the idea of possibly writing a novel set in the '20s about a plot to assassinate Hitler. That led him to the Weimar-era journalists of the Munich Post, whose forgotten tabloid-style exposés of Hitler and his party Rosenbaum unearthed in the city's Monacensia library.

"I was struck by just how contentious just about every fact of Hitler's past was," Rosenbaum says. "I really began to feel that there was something to be done about the unresolvedness of these questions." An early version of his research into Hitler's rumored Jewish ancestry was published in Travels with Dr. Death, a collection of his journalism issued by Viking in 1991. That same year, his investigation into Hitler's relationship with his half-niece Geli Raubal, who allegedly committed suicide in 1931, appeared in Vanity Fair.

But the project really took shape when Rosenbaum came upon a copy of Albert Schweitzer's Quest of the Historical Jesus in a secondhand bookshop in Jerusalem. "I thought it was fascinating the way Schweitzer investigated the agendas behind these 19th-century lives of Jesus. I began to think there was something similar to be looked into with lives of Hitler, the way those writing were projecting onto inconclusive and incomplete and tendentious evidence their own theories of the nature of evil." In 1991, Rosenbaum and his longtime agent, Kathy Robbins, approached Random House publisher Harry Evans about the subject. Evans in turn passed it on to editor Jonathan Karp.

The War Against Why

One of the most remarkable things about the book is Rosenbaum's use of interviews to illuminate subtle shifts in various Hitler explainers' thinking. "The one thing I've found in journalism," he says, "is that you can read everything someone has written and you still learn more about the heart and soul of their preoccupations talking to them face to face." Rosenbaum is also a master of provoking dramatic encounters, whether catching the infamous revisionist historian David Irving in a revealing slip of the tongue, causing the beleaguered Goldhagen to mysteriously break off their meeting or being abruptly shown the door by the irascible Claude Lanzmann, director of the documentary Shoah.

Lanzmann, who has denounced what he calls the "absolute obscenity of the very project of understanding," is a particular target of Rosenbaum's ire. After a brilliant analysis of the contradictions in what he calls Lanzmann's "war against the question Why," Rosenbaum devotes a chapter to the director's public humiliation of an Auschwitz survivor who, at a conference, asked questions about the Holocaust he disapproved of. As described by Rosenbaum, it is indeed a disturbing incident. But he then g s on to say that Lanzmann and his gang of intellectual enforcers want Shoah "to be the final solution of Hitler explanation; further discussion must be terminated if not exterminated." Isn't this implicit equation of Lanzmann with Hitler taking things -- perhaps deliberately -- too far?

"I don't think that's what I'm saying," Rosenbaum says vehemently. "I share Lanzmann's anger at specious, easy explanations, and I think I say I sympathize with what drives him, with his sense of urgency. I think what upset me was his issuing dicta as to what can and cannot be said, saying that there's an end of discussion after his movie, going from someone who's investigating to someone who's censoring."

It's as though Rosenbaum is saying that, in the matter of Hitler and the Holocaust, the case must remain open. But after fifteen years, thousands of pages of reading and hours of tape-recorded conversation, does Rosenbaum think he's gotten any closer to the answers?

"No," he says, without a second's pause. "I feel I've clarified the questions, but it may have to live without having all the answers we want. And that to me is very upsetting."