Trump campaign foreign-policy advisor George Papadopoulos’ relationship with a mysterious unnamed professor was at the center of the first guilty plea in special prosecutor Robert Mueller’s investigation into Russia campaign meddling.

In a 14-page Statement of Offense stipulated to by Papadopoulos, Mueller’s office outlines how the campaign aide was in contact with the professor, who put him in touch with a Russian foreign ministry official, and an unnamed women whom Papadopoulos incorrectly believed was Putin’s niece. The contacts were initially aimed at arranging a meeting between then-candidate Donald Trump and Russian president Vladimir Putin.

The Washington Post has reported (paywall) that Joseph Mifsud, on the staff of Stirling University in Scotland—and, the Post said, also with the London Academy of Diplomacy—is “likely” the professor in question. The Post based its assessment on an email described to the Post in which Papadopoulos reportedly identifies Mifsud.

(The Post reports Mifsud told them in August that he had “absolutely no contact with the Russian government” and said he was an academic whose only ties to Russia are through “academic links.” Neither Quartz nor the Post have been able to reach Mifsud for comment after news of Papadopoulos’ guilty plea.)

Quartz has found further evidence that Mifsud is probably the professor in question. Here’s what points in that direction:

1. Mifsud attended a conference at Russia’s Valdai Club on the same dates as “the professor”

“I am flying to Moscow on the 18th for a Valdai meeting, plus other meetings at the Duma [Russia’s parliament],” the professor emailed Papadopoulos on April 11, 2016, according to the prosecutors’ statement. Mifsud spoke on April 19 at a panel at the Valdai Club, a think tank with close ties to Putin’s government and at which Putin appears every year for a headline event.

Mifsud has a profile page on the Valdai Club’s website and has written three articles for the think tank.

2. Mifsud matches “the professor’s” description in the affidavit

Papadopoulos told the FBI that a “professor of diplomacy based in London” who is “a citizen of a country in the Mediterranean” and “an associate of several Russian nationals” is the person who told him Russians have “dirt” on Hillary Clinton, including thousands of emails. Mifsud is a Maltese citizen, who reportedly teaches at the London Academy of Diplomacy.

3. Mifsud and Papadopoulos are friends on Facebook

Here’s a screenshot:

4. Mifsud knows the man who is probably the Russian foreign ministry contact

The Post has also reported (paywall), based on emails it has seen, that Ivan Timofeev, a “senior MFA [Ministry of Foreign Affairs] official” is likely the Russian official Papadopoulos was in contact with (the men were introduced by “the professor,” according to the prosecutors’ statement.).

Mifsud and Timofeev definitely know each other: Timofeev moderated the panel at which Mifsud spoke in April 2016. The two men were reported to have appeared at an event at the Russian International Affairs Council (a state-funded think tank where Timofeev is listed on the staff) to present Global Energy 2015-2016, a report that they co-authored with several other academics.

5. This wasn’t Mifsud’s first visit to Russia

Diplomacy professor Nabil Ayad, who said he has worked with Mifsud, told Quartz that Mifsud, “Goes to Russia occasionally to attend conferences and meetings. He doesn’t stay for long, normally two or three days but he has, I think, good links with universities there.”

“I know that he has good links with the Russians but I can’t tell whether he has links with officials there,” said Ayad. “But he doesn’t have any professional…it’s a matter of education and relations as far as I know.”

When asked if it was plausible that Mifsud helped connect Papadopoulos to the Russian government, he said: “Maybe it was a casual occasion because he happened to be there and he knew some Russians and introduced them, but I don’t think he was trying to do anything sinister,” he said.

Ayad believed Mifsud is currently in Rome (the court document states that Mifsud and Papadopoulos met in Italy) and was trying to phone Mifsud to put him in contact with Quartz but could not get hold of him. (When Quartz phoned Mifsud’s cell phone, it went straight to voicemail.) “It’s important for him to clear his name,” Ayad said.

6. Mifsud’s profile disappeared from a London legal practice’s website as rumors swirled

On the morning of Oct. 30, Mifsud was listed as the director of International Strategic Development at the London Centre of International Law Practice (LCILP). Later that afternoon, his profile page appeared to have been taken down. (It is still accessible via a cached link.)

The LCILP’s phone went straight to voicemail when called. Early on Monday, the LCILP’s address was listed as: Ground Floor South, 14 Old Square, Lincoln’s Inn, London. When Quartz visited that address—which is at one of London’s four medieval Inns of Court, of which every British barrister has to be a member—it didn’t find the name listed anywhere. A man found exiting the small building told Quartz he works there and he had never heard of the company—”and I spend a lot of time here,” he added.

Later on Monday, that address had been removed from the website. Quartz visited the other address on the website, just around the corner at 8 Lincoln’s Inn Fields, and found a buzzer with LCILP’s name on it. When pressed, a visitor was put straight to an answerphone. Inside the building, LCILP’s name was on a mailbox but there was no other sign of the company in the building, which had at least one floor that seemed to be unoccupied.

So, just who is Joseph Mifsud?

His scrubbed profile on the LCILP website lists myriad positions that Mifsud has filled, as does a profile on the European Parliament’s website (pdf). He is president of the Euro-Mediterranean University in Slovenia, according to the EU, and has worked in Malta’s foreign ministry, representing the island nation at the Council of Europe.

The LCILP says he has worked in Malta’s ministry of education, is a member of the Valdai Club and the European Council on Foreign Relations think tank. It lists his geographical areas of expertise as basically the whole world (outside Latin America): Europe, USA, The Middle East, Africa, and Asia.

Mifsud is listed as a “professorial teaching fellow” at Stirling University. The administration support officer at the university said he was a dean for international development and diplomacy but that “he’s not often on campus here…he does a lot of traveling.”

When Quartz phoned the Academy of Diplomacy at Loughborough University London, a reporter was told that Mifsud was not listed in any of their internal systems.