LJUBLJANA, Slovenia—One day not long ago Melania Trump’s biographer in her Slovenian homeland, politician and author Igor Omerza, was flipping through hundreds of thousands of names on “UDBA Net.” It’s an online database of the secret police archives of Communist Yugoslavia before the country came apart in the 1990s, which is when Slovenia won its independence. And among the IDs that appeared there, one name jumped out: Viktor Knavs, with the same birthday, parents, and hometown as the father of Melania Trump, who just became a naturalized American citizen.

The entry was cryptic, as such things are, but it noted “the person is registered in the criminal record” and cited articles 226 and 235 of the Yugoslav penal code. There is no indication of a charge, an investigation or a conviction, one way or the other.

According to a copy of the 1970 code, which was current at the time, article 226 involved the acquisition, sale or production of goods without the explicit permission of the Socialist Federal Republic of Yugoslavia. Penalties ranged up to eight years in prison for someone organizing such commerce.

Article 235 involved tax evasion, with a maximum penalty of 10 years in jail depending on the amounts of money involved.

But because there are no other specifics, and because these allegations were made more than 40 years ago under a repressive police state, it is not clear how serious they really were.

At a time when some people are being denied permanent residence and citizenship in the United States because of their records in other countries, the case of Viktor Knavs is especially interesting.

David Leopold, an immigration attorney who formerly headed the American Immigration Lawyers Association, told The Daily Beast that a tax fraud conviction—if one exists against Knavs—could have kept Knavs from getting a green card, and could now potentially be grounds for revoking his citizenship.

In Slovenia, Knavs’ lawyers have said that despite the secret police record he was never convicted, charged, or even investigated for tax evasion, but they reportedly acknowledge he was investigated for smuggling.

Leopold said that for Knavs’ record to jeopardize his application, there would have to be evidence he committed a crime “of moral turpitude,” and tax crimes sometimes fit into this category.

Knavs’ immigration lawyer, Michael Wildes (sometimes called “the attorney to the stars”) told The Daily Beast. “Mr. Knavs’s application for U.S. citizenship was properly executed and adjudicated, consistent with the Immigration and Nationality Act. His naturalization process was no different than anyone else seeking citizenship in this country.”

We asked Wildes and the office of First Lady Melania Knavs Trump to explain basic questions:

What were the specific charges in Yugoslavia, if any? Were they resolved, and if so, how? Were they acknowledged in Knavs’ applications for permanent residence and citizenship? If not, why not?

Wildes did not respond to any of the specifics and asked for “proof” that the Viktor Knavs in the UDBA records was the same man.

The first lady's spokesperson, Stephanie Grisham, declined to answer questions about Melania Trump's father, saying it was office policy not to "comment on her parents as they are not part of the administration and deserve privacy."

Like the Stasi in Communist East Germany, vividly depicted in the Oscar-winning 2006 film The Lives of Others, Yugoslavia’s UDBA was infamous for listening in on private phone conversations, penetrating relationships, ruining friendships and families.

The archive is available to researchers like Omerza—who published a 2016 book with co-author Bojan Pozar, Melania Trump: The Inside Story—and contains more than a million dossiers of UDBA informers, collaborators and agents, as well as names of people accused of criminal activities.

Moving his finger on the track pad as I watched last week, Omerza skipped down the list. Some former Yugoslavs ended up there as persons “threatening the Socialist regime,” he said, others as common criminals under investigation.

“Here is Melania Trump’s father’s record, under #421269,” Omerza said, pointing at the once secret document. There were only a few lines under “Knavs, Viktor.”

The file shows him born on November, 23, 1941, included personal details: place of birth, parents’ names, his gender, his marital status and home address. All square with public records for Melania’s father. His occupation is listed somewhat archaically as “a commercial traveler,” in literal translation. We would say a traveling salesman. We also know his main business was cars and car parts.

When the file entry, which Omerza provided to The Daily Beast, was created in 1976, the future first lady was six years old.

When Omerza dug into Slovenia’s court archives, he did not discover any record that showed Viktor Knavs was convicted or sentenced. This left him wondering, since Knavs apparently was suspected of an economic crime, how did he manage “to get off the hook?”

Giving Knavs the benefit of the doubt, it is also possible the accusations of criminal behavior were, from the beginning, an effort by the UDBA to pressure him in some fashion

The file entry on Melania Trump’s father is full of numbers and abbreviations that are impossible for the uninitiated to decipher. But they were no mystery to Omerza, a former mayor of Ljubljana and a member of the Slovene parliament who has published nine books about the UDBA’s informers, collaborators, kidnappers, interrogators, murderers and victims.

In recent years, Slovenia, like other formerly communist Eastern European nations, has become serious about opening a window on its past. First in 2011 and then again in 2014 a majority voted to reveal to the public what was a secret portion of the UDBA archive.

Today, with an easily obtained permit just about anybody can have access to the UDBA’s documents, although sometimes the state blacks out sensitive details. No information was redacted, however, in the Viktor Knavs entry.

The first mention in his record is “JV,” which, according to Omerza, means that the notation about Knavs’ record “concerned public security," Omerza said. But that was an offense broadly construed under communism.

Melania, her sister and parents lived in Sevnica, a provincial town on the Sava River with a population of about 5,000 people. Her mother, Amalija Ulcnik, spent almost three decades working hard, drawing and cutting patterns for children’s clothing at a local textile factory. But the Knavs had a lifestyle that others envied.

Neighbors who talked to The Daily Beast recalled that Melania’s parents had traveled abroad to France, Italy, Austria and Germany for work, bringing back beautiful things that very few people could afford in their hometown. (There is no evidence at present to indicate the Knavs came by these luxuries illegally.)

Viktor Knavs worked first as a driver for the Jutranjka textile factory, repaired cars, and eventually started his business selling automobiles and parts he brought in from abroad. In that sense Melania’s father was, literally, a used car salesman. Also: mopeds.

Even in Communist times, when few people could afford any automobile and those who could afford one had to wait for years to get their vehicle, Knavs was the proud owner of a Mercedes.

“His wife and daughters dressed in beautiful clothes that Melania’s mother made for long hours after her work, Viktor drove a Mercedes, the family went on vacations abroad—so I am not surprised that the UDBA investigated Knavs,” said Polona Kosak, a 68-year-old housewife in the Knavs’ old neighborhood.

Kosak, like most in her generation, has vivid memories of the way the secret police operated. “I remember how my own parents, thoughtful intellectuals, were afraid of UDBA’s political police, which kept an eye on well-traveled people, often turning them either into informers or collaborators.”

The UDBA files identify informants and collaborators. Knavs is not among them.

In 2015, after Donald Trump announced his run for the presidency, Omerza and his colleague Urska (who did not want to be identified by her full name out of fears of retaliation) went to photograph the house of Melania Knavs Trump’s parents in Sevnica, street address Ribniki 21. It’s a tidy modern house on a quiet road in what could easily be a small town in neighboring Austria. Omerza and Urska did not realize that a man sitting by the wall and rubbing something with a towel was Viktor Knavs himself.

Omerza and Urska drove on along the street but in a few minutes a Mercedes S-class sedan closed in on them at high speed. “Knavs stopped his car in front of us, blocking the way,” Urska recalls, and she though, judging by the rage on his face, he “was going to become physical with us.”

“I was shocked,” she told The Daily Beast, “thinking, 'What idiot would act like this?'”

Knavs is a big man (some have suggested his build resembles Donald Trump’s) and he couldn’t climb out of the car as fast as he seemed to want. “So we drove around him to avoid an altercation, and just kept driving ahead, but Viktor took off after us again, and raced after us on the highway for a few minutes until it looked like he gave up. It was like a cinematic car chase by the dangerous father-in-law of American President Donald Trump.”

Last year, Knavs filed a lawsuit in Ljubljana against Omerza’s co-author Pozar, who had published a story on his website in 2016 with the headline "Documents, tax fraud: was Viktor Knavs, Father of Melania Trump, in Jail?!"

Pozar mentioned the UDBA record in his story.

So far, Judge Irena Skulj Gradisar has had only held one hearing on the case. Knavs did not show up in Ljubljana court. Dnevnik.si, a Slovenian publication, reported that Knavs was represented by his two lawyers, Natasa Pirc Musar and Rosana Lemut Strle, who acknowledged that “indeed in 1978 Knavs had been the target of an investigation into smuggling,” but that the prosecutors had stopped the investigation.

As noted earlier, the lawyers denied that Knavs had ever been investigated for tax evasion and insisted that their client had neither been sentenced nor had he ever spent time in jail.

Pirc Musar, the subject of a Daily Beast profile in 2017, did not respond to queries about this case.

There are many other stories about Viktor Knavs. There have also been several lawsuits to try to stifle publications, or punish them after the fact.

The editor of the local magazine Suzy said he would like to talk to The Daily Beast, but was barred from doing so after a court ruling.

What do the Slovenes make of Knavs’ secret police record? They don’t doubt it, but they put it in context. “To me Viktor Knavs is an old-fashion representative of an era that has nothing to do with modern Slovenia, a small country where everybody knows everything about each other,” says magazine editor Dejan David Kemperl.

Omerza vows to keep investigating, “We’ll be digging and reporting until we know all the truth.”

With additional reporting by Betsy Woodruff and Michael Daly

Editor's note: A previous version of this story incorrectly stated that Viktor Knavs served as a driver for the mayor of Sevnica. Rather, he drove for the mayor of Hrastnik, a small town near Sevnica. The Daily Beast regrets this error.