Model Melania Knauss with Donald Trump for the opening night of the musical “Dance of the Vampires” Dec. 9, 2002, at the Minskoff Theatre in New York. (Mark Mainz/Getty Images)

Newly published nude photographs of Melania Trump, the wife of Republican presidential candidate Donald Trump, have raised questions about the story of her immigration to the United States and how the Slovenian-born former model gained her legal status here — questions that the Trump campaign is not answering.

Melania Trump has said she came to the country in 1996, but the photos were taken in New York in 1995. She met Donald Trump in 1998, and they were married in 2005. So what do we know about how Melania Trump came to the United States?

Q: What has Melania said about her immigration?

A: Melania Trump has said she came to the United States on a legal visa in 1996, got a green card in 2001 and then became a U.S. citizen in 2006.

Melania Trump is a former model, jewelry designer — and potential first lady. Here's your primer on The Donald’s third wife. (Julie Percha/The Washington Post)

“I came here for my career,” she told Harper’s Bazaar in January. “I did so well. I moved here. It never crossed my mind to stay here without papers. That is just the person you are. You follow the rules. You follow the law. Every few months you need to fly back to Europe and stamp your visa. After a few visas, I applied for a green card and got it in 2001. After the green card, I applied for citizenship. And it was a long process.”

Then, in February, she told MSNBC: “I follow a law the way it’s supposed to be. I never thought to stay here without papers. I had visa. I travel every few months back to the country, to Slovenia, to stamp the visa. I came back. I applied for the green card. I applied for the citizenship later on after many years of green card. So I went by system. I went by the law, and you should do that.”

On Thursday, Melania Trump tweeted an additional explanation — but no additional details:

“Let me set the record straight,” she wrote. “I have at all times been in full compliance with the immigration laws of this country. Period.”

Q: Who sponsored Melania to come to the United States? What kind of visa did she hold?

A: The Trump campaign has been vague. This week, Trump campaign spokeswoman Hope Hicks responded to a list of detailed questions of Melania Trump’s immigration status with only one line: “Melania followed the laws and is now a proud United States citizen.”

Most of what we know about how she first came to the United States comes from Paolo Zampolli, an Italian-born businessman based in New York who once owned modeling agencies.

He told The Washington Post this week that his agency, Metropolitan Models, sponsored Melania Knauss for an H-1B work visa in 1996 after he spotted her while scouting models in Milan and Paris. Working models are eligible for an H-1B if they can show “distinguished merit or ability” in their field. Zampolli said Melania Knauss qualified based on her past work as a model in Europe.

Q: So she has said she came in 1996?

A: Yes, multiple times. Her official biography in the program of the Republican National Convention in Cleveland last month indicated she came to the United States in 1996. So did her biography on the Trump Organization website. That page was recently taken down after it emerged that a line indicating that Melania Trump had earned a college degree at a Slovenian university was false; she studied at the school before dropping out to pursue modeling in Paris and Milan.

Q: But the nude photographs were taken in New York City in 1995?

A: Correct. The photographs originally appeared in the French magazine Max and were published again in the New York Post last weekend. Marc Dolisi, chief editor of Max at the time, told The Washington Post that the pictures appeared in the February 1996 edition of the magazine and had been shot in November or December of 1995. Jarl Ale de Basseville, the photographer, said the shoot was conducted in New York.

Q: How can the discrepancy be explained?

A: Only Melania Trump can explain the discrepancy, which was first reported by Politico. The campaign has not responded to questions asking how those photos could be shot in 1995 if Melania Trump arrived in 1996.

Q: So does that mean Melania Trump was in the United States illegally in 1995?

A: It’s not clear. Dolisi and de Basseville both told The Washington Post that Melania Trump was not compensated for the Max magazine photo shoot. She was a relatively unknown model at the time. Taking part in magazine photo spreads for free is common for models at that level because the exposure can help them secure commercial work.

Q: Why is it important that Trump was not paid?

A: Without pay, she could have been here legally on a visitor’s visa. Foreigners coming to the United States for brief stays can obtain B1 or B2 visitor’s visas allowing them to stay in the United States as either a tourist or a business visitor attending a meeting or other work event. It is, however, illegal to work in the United States on a visitor’s visa; that kind of illegal work has tripped up many other people who wish to legally immigrate to the United States. People applying for or holding a visitor’s visa are asked both at an embassy or consulate abroad and at the port of entry upon arrival whether they intend to work. If they come to the United States planning to work and claim otherwise, that’s immigration fraud.

It is unclear, however, if she got any other kind of compensation during her 1995 stay, such as airfare and lodging.

Q: Did Melania Trump ever come to the United States on a visitor’s visa?

A: We don’t know. The Trump campaign has not answered this question.

Q: Did Melania Trump do any other work in the United States before 1996?

A: We don’t know. The Trump campaign has not answered this question.

When she first arrived in the United States, Melania Trump shared an apartment for a time with Matthew Atalian, a photographer who was friendly with Paolo Zampolli. In an interview, he said she moved in either in 1995 or in 1996 and lived with him for about a year and a half. He said he agreed to let her move in with him at the request of Zampolli, who paid her rent. His understanding at the time, he said, was that she was “fresh” to the United States.

Q: Melania Trump described having to return to Slovenia every few months to get her visa stamped, citing her willingness to undertake these trips as a commitment to complying with U.S. immigration law. Why did she need to do this?

A: We don’t know. The Trump campaign would not answer this question.

Immigration experts said that people who receive H1-B visas typically receive them for three years and are able to renew them for another three years. They expressed some confusion as to why Melania Trump would need to periodically return to Slovenia if she held an H-1B visa. However, several said the specifics of her situation might have required it. Only Melania Trump could describe her own experience.

Q: How did Melania Trump get a green card?

A: We don’t know. The Trump campaign would not answer this question.

A green card allows a foreigner to permanently reside in the United States. It is the golden ticket of the U.S. immigration system and highly sought after by millions of immigrants.

There are several avenues Melania Trump could have pursued to get a green card. She could have won a lottery for people who immigrate from countries that don’t have high immigration rates to the United States.

She could have sought a green card as a person of extraordinary ability, though experts cast doubt that she had been sufficiently successful in her modeling career to qualify in this category.

She could have been sponsored for a green card by an employer who made a case that there were no Americans available to fill a particular job. That process is not easy; it requires the employer to show that they have attempted to fill the job, by advertising it publicly. Michael Wildes, an immigration lawyer who has done work for the Miss Universe pageant and the Trump Organization, said his firm will typically not help models pursue this kind of green card, as it is too difficult to show that a modeling job could not be filled by an American. He said, however, that models can sometimes qualify for a green card on these grounds by seeking employment in a different field for which they are also qualified, like graphic design. Wildes said he did not have permission from the Trump Organization to comment on any specific case, including Melania Trump’s.

Immigrants can also obtain a green card through marriage. Melania and Donald Trump were married in a very public ceremony in 2005, four years after she has said she obtained her green card.

Q: Shouldn’t there be some documents available that would shed light here?

A: Certainly. But experts said Melania Trump’s immigration records would typically not be available for public release without her permission. The Washington Post asked Hicks to release copies of these records; she did not respond to this question.

Q: Isn’t it hypocritical for the Trump campaign not to answer these questions, given that Trump has made cracking down on illegal immigration the centerpiece of his campaign? And given that he waged a very public campaign to insist that President Obama release a copy of his birth certificate to prove that he was born in the United States?

In March, Donald Trump said he was “totally committed to eliminating rampant, widespread H-1B abuse and ending outrageous practices such as those that occurred at Disney. I will end forever the use of H-1B as a cheap labor program, and institute an absolute requirement to hire American workers first.”

A: That’s a question for the voters.

Alice Crites contributed to this report.