In an interview room at Tullamarine Airport in Melbourne, an Australian immigration officer sat down across from the tennis star Novak Djokovic.

The officer started with a warning.

“I am now going to caution you,” the officer said, according to a public transcript both sides have agreed is accurate, “that if you provide false or forged documents or false or misleading information you can be prosecuted under Australian laws.”

Even before his plane touched down in Melbourne last Wednesday night, Djokovic’s application for a visa to play in next week’s Australian Open was under scrutiny, and questions swirled about whether he would be allowed into the country. The answer, at least initially, was no. Australia, which requires all foreign visitors to be vaccinated, but grants exemptions in limited cases, canceled Djokovic’s visa after his airport interview, only to have a judge reinstate it on Monday on procedural grounds.

“This is his greatest victory, greater than all the Grand Slams that he has won,” his mother, Dijana, said at a news conference on Monday in Belgrade, Serbia.

Now, as Australia’s top immigration official considers rejecting Djokovic’s visa again and its prime minister calculates the political cost of the fight, published reports and Djokovic’s own social media posts have raised questions about the validity of his visa paperwork and his actions in the days around Dec. 16, when, by his account, he learned he had tested positive for the coronavirus.

Even the positive test result, which is at the heart of the medical exemption that Djokovic needed to obtain to play in the Australian Open, has been cast into doubt by a published report.

On Monday, the German newspaper Der Spiegel reported that it had scanned the unique computer code attached to Djokovic’s test result — which was included in court filings related to his visa appeal — and found that it initially reported the test was negative for the virus. But just over an hour later, when Der Spiegel journalists and others checked the code again, the linked webpage said Djokovic’s test was positive. That was still the case on Tuesday morning.

Djokovic has not commented on the merits of his case, and his family declined to address specific questions about his activities on Monday, when his brother Djordje declared at the news conference in Serbia that “truth and justice came to the light” when Novak Djokovic was released from detention with his visa restored.

Djokovic’s agent and spokesman did not immediately respond to a request for comment on Tuesday.

The confusion about Djokovic’s test result, though, only renewed questions about his actions on the day of the test and the week that followed.

If Djokovic tested positive Dec. 16, then his actions in the ensuing days — when he should have been isolating — could have endangered the health and safety of dozens of people. On the day of his test and the two that followed, for example, Djokovic’s own social media postings and contemporaneous accounts show him repeatedly appearing at public events without a mask and around children and strangers even after he had recorded a positive test.

What has Djokovic said?

To obtain a visa to enter Australia, Djokovic and his lawyers submitted documents that said he had tested positive for the coronavirus on Dec. 16. He cited that positive result when he was interviewed by Australia Border Force officials upon his arrival in Melbourne.

Djokovic produced the Dec. 16 test result “unprompted,” the Australians said in a court filing. A transcript of his interview, which was recorded, included the following exchange:

INTERVIEWER: Thank you. Have you ever had COVID?

DJOKOVIC: Yes.

INTERVIEWER: So when did you?

DJOKOVIC: I had COVID twice, I had COVID in June 2020 and I had COVID recently in — I was tested positive — PCR — 16th of December 2021.

INTERVIEWER: Thank you. Sorry what was the date? 16th of December?

DJOKOVIC: 16th of December 2021, I have the documents as well to confirm that if you want I can provide — just as a —

INTERVIEWER: Thank you. I’ll just make a photocopy of those documents —

The filing also includes the timing of the test, which was collected about 1 p.m. Dec. 16, and of a positive result returned seven hours later.

What about the medical exemption?

The positive result was used to justify Djokovic’s application for a medical exemption to play in the Australian Open, which requires all tournament participants to be vaccinated but which granted multiple exemptions to the rule.

On Jan. 4, Djokovic announced on his Instagram account that he had received the exemption he needed. Alongside a smiling photo, he said he was headed to Australia.

It was what he had done in the days after his positive test, though, that now threatened to cause him problems.

A public figure, in public.

On Dec. 16, the day Djokovic sought a test for the virus, Djokovic was honored with a stamp by the Serbian postal service and toured its facility. In photos from the event, Djokovic appears with the acting director of Serbia’s postal service, Zoran Dordevic. Neither Djokovic nor Dordevic is masked in a photo, or in other pictures from the event.

Djokovic also took part in an hourlong panel discussion that day at a tennis center that bears his name. The topic? “The role and establishment of authority in the development of character and discipline.” In a video of the event posted on YouTube, neither Djokovic nor any of the other panelists wears a mask.

A day later, Djokovic reportedly appeared at an event to honor youth tennis players at the tennis center that bears his name. None of the dozens of people in a group photo from the ceremony, including Djokovic, whose positive test result was confirmed a night earlier, wore a mask.

The next day, Dec. 18, Djokovic took part in a photo shoot with the French sports publication L’Equipe. The newspaper has published the photos repeatedly in its coverage of his visa dispute.

Serbia’s prime minister, Ana Brnabic, told Reuters in an interview on Tuesday that if Djokovic attended events after learning he was positive that he would have “clearly violated the rules.”

What now?

Djokovic, who confirmed in his airport interview that he is unvaccinated, has said little publicly beyond two Instagram posts thanking his supporters. He was “pleased and grateful” about the judge’s ruling, he said on Monday, and clearly planning to stay in Australia, where he is scheduled to begin the defense of his Australian Open title next week. He is already practicing.

Australia’s immigration minister, meanwhile, continues to “thoroughly consider the matter” of expelling him, according to his spokesman. One thing government officials will weigh is if Djokovic was truthful in his statements and declarations.

As the officer noted in his first airport interview, providing false or misleading information could be deemed a crime in Australia. Losing his visa again could result in Djokovic’s being barred from returning to Australia — and to the tennis season’s first major tournament — for at least three years.

At the news conference in Serbia, Djokovic’s brother Djordje spoke repeatedly about the transparency of the process that had vindicated his brother.

But when he was confronted with the contradictions in the timing of Djokovic’s positive test result and his multiple public appearances that week, Djordje Djokovic abruptly ended the questioning.

“OK, so, uh, this press conference is adjourned,” he said.