BUCHAREST, Romania -- Working out of a human rights office in a former mansion in this Balkan capital, a University of Maryland professor is leading an official inquiry into Romania's ugly communist past. His work has stirred a vicious backlash from people who want that past left alone.

Vladimir Tismaneanu, born in Romania and now a U.S. citizen, heads a national commission appointed by President Traian Basescu earlier this year. "A democratic political community cannot be built on amnesia," said Tismaneanu, 55, an energetic man who favors jeans and casual shirts.

The commission's 20 staff experts, drawn from the Romanian academic world, are poring over scholarly research and papers in state archives. "Our goal is not to break new ground," Tismaneanu said in an interview, "but to bring together the mountain of existing material, with every statistic, every fact, about our communist past."

His commission, which includes historians, political scientists and a philosopher, has no power to issue subpoenas or bring formal charges. Another commission, appointed by Parliament, probes allegations of crimes by individuals.

But Basescu has said that the Tismaneanu panel's report will become "an official document of the Romanian state" and that he will seek a parliamentary endorsement for it. Plans call for the report to form the basis of a textbook on communism for Romanian high schools.

In the years since communism's fall here in 1989, Romania has become a close U.S. ally, sending troops to Iraq and agreeing to a long-term U.S. military presence on its soil. President Bush hosted Basescu at the White House on Thursday.

The man Basescu appointed to catalogue the four-decade communist era is a professor of government and politics at the University of Maryland's College Park campus and the author of standard works on Romanian communism and on Eastern Europe after the revolutions of 1989.

He grew up in Romania under communism, earning a BA degree at the University of Bucharest in 1974. He left the country in 1981 and later campaigned against the dictatorship of President Nicolae Ceausescu, speaking on Radio Free Europe/Radio Liberty and the Voice of America.

Romania's sometimes halting steps toward democracy since Ceausescu's overthrow in 1989, along with the persistence of corruption, have hindered the country's advance toward membership in the European Union, set for 2007. Hundreds of former high-ranking communists and secret police agents continue to hold top positions in government and business.

The Conservative Party leader, Sen. Dan Voiculescu, was recently accused by Romanian newspapers of operating decades ago under the code name "Felix" and furnishing economic reporting to the much-feared Securitate -- the KGB of communist Romania. After initially denying the allegations, he called a news conference at which he confirmed them but made no apology.

"I collaborated, just as millions of Romanians collaborated," Voiculescu said, adding that "no one was injured by my reports." He has abandoned a bid to become deputy prime minister.

Former prime minister Adrian Nastase, meanwhile, is the target of three criminal investigations by Romania's anti-corruption agency and has resigned as Social Democrat Party chief and speaker of the lower house of Parliament. He is accused of taking bribes to make political appointments and of receiving improper campaign contributions during an unsuccessful presidential campaign in 2004.

Despite many obstacles, some victims of communism have managed to win important victories. Doina Cornea, a gutsy professor of French who is widely considered the leading anti-communist dissident to have remained in the country, demanded and got her security files. She received two wooden boxes containing about five feet of records, including surveillance photographs.

Sitting recently in the book-lined studio of her 19th-century cottage in Cluj-Napoca, capital of the Romanian region of Transylvania, she displayed handfuls of pictures. One showed a neighbor looking over the fence, another the uniformed policeman who stood menacingly in front of her house for more than a year. She was followed everywhere, jailed and roughed up for leading protests.

Cornea noticed that one very knowledgeable informer was designated "X." She demanded to know who the snoop was and, two years later, was informed that "X" was Eugen Uricaru, president of the writers' union. Cornea said she wrote to Uricaru and told him she'd learned what he did. When he failed to reply, she waited a month, then held a news conference to unmask him. Uricaru did not seek the union presidency again.

The Romanian novelist Augustin Buzura also obtained his security files and found that 56 informers, including close friends and associates, had reported on him.

The 67-year-old writer, winner of the country's highest literary prizes, expresses skepticism that any commission can manage the hydra-headed issue of communism. "Practically, the communist era has not ended," he said. "The mentality is the same. No matter how extraordinary a commission may be, it cannot fathom in a period of six months the catastrophe that was communism."

Tismaneanu, who commutes between College Park and Bucharest, works out of a mansion in the capital that houses the Group for Social Dialogue, a political and human rights organization formed during the 1989 revolution. The house was once the scene of parties held by Nicu Ceausescu, the dictator's son.

Tismaneanu shrugs off criticism that his parents were committed communists and that his credibility is hurt by his friendship with Ion Iliescu, who held various posts under Ceausescu and served twice as president after 1989.

Nationalist politicians have harassed Tismaneanu relentlessly. The extremist Greater Romania Party published articles asserting that he was a Zionist operative and stooge of the Americans.

"A Greater Romania Party senator made a speech in Parliament," he recalled, "about 'five reasons why Tismaneanu should not head the commission,' and reason number three was that I was a Jew."

The mainstream newspaper Ziua printed an allegation that Tismaneanu had been a Securitate agent as a student in the United States, a story for which it later apologized. (A government agency certified that his political past is clean.)

He has also drawn criticism for supporting the war in Iraq. "Saddam himself was a weapon of mass destruction," he has said of the deposed Iraqi president.

Meanwhile, he continues his research. Is closure possible? He is careful to say that his campaign is about moral recovery, not vengeance.

"I believe we are able to somehow approach the past in a way that combines both analysis and compassion," he said.