Ousted national security adviser Michael Flynn has kept out of sight as the federal investigation into his foreign ties ramps up. He’s eschewed public appearances and communicated almost exclusively through his team of lawyers since he was forced out of the Trump administration in February.

Flynn’s former lobbying client, however, is speaking out about their relationship.

In a speech Monday before the 36th Annual Conference on U.S.-Turkey Relations, Turkish businessman Kamil Ekim Alptekin directly addressed the $530,000 he paid to Flynn’s consulting firm in the heat of the 2016 election. He denied there was anything untoward about their work.

“As many of you have read in the media, I hired the Flynn Intel Group in 2016 before the election with a mandate to help me understand where the Turkish-American relationship is and where it’s going and what the obstacles to the relationship are,” Alptekin told the room, according to news reports.

The speech was delivered in the presidential ballroom of the Trump International Hotel in Washington, D.C.—a stone’s throw from the White House.

According to the New York Times, Alptekin, who frequently tweets favorable stories about the Trump administration, has been swept up in Flynn’s legal troubles, as federal investigators have issued subpoenas for Alptekin’s records, research, contracts, bank records and other communications related to his work with Flynn Intel Group.

There is no indication that Alptekin himself is a target of investigation. He told ABC News in an interview this week that he “cannot comment” on whether he he’s been questioned or subpoenaed by U.S. authorities.

The exact nature of the work Flynn did for Alptekin is key to unraveling the complex web of foreign entanglements that brought the onetime national security adviser under both federal and congressional scrutiny. Since the failed coup attempt against Turkish President Recep Tayyip Erdogan last July, the powerful businessman has been leading the effort to rehabilitate the image of Turkey and its increasingly authoritarian leader in the U.S.

“In the United States his name definitely did come up, amid the circle of people who kind of keep an eye on these things,” Scheherazade Rehman, professor of international business at George Washington University’s Elliott School of International Affairs, said of Alptekin. “Clearly it’s a totally legitimate operation in terms of following all the lobbying rules that we have, but the lobbying is pretty intense. They’ve stepped it up. There’s no question that after the coup, they have seriously stepped it up.”

Erdogan has cracked down on dissent, jailing journalists and protesters en masse, since the move to oust him from power. Most recently, he eked out a victory in an April referendum that granted him vast constitutional powers. Though President Donald Trump congratulated Erdogan on that win, international monitors reported that the voting was rife with fraud.

Representatives for Alptekin agreed Thursday to pass along emailed questions, but TPM did not receive a response. A host of Washington, D.C.-based groups and individuals associated with Alptekin, who appears to be a significant power player in the capital, also declined or did not respond to requests for comment.

Alptekin had worked on Capitol Hill as a congressional fellow in 2003, and he currently serves as chairman of the Turkey-US Business Council and representative for Turkey on the board of the U.S.-based Nowruz Commission, a nonprofit public diplomacy organization. He has significant business interests in the international real estate and defense industries through his companies EA Property Development, EA Aerospace and ATH Defense and Security Solutions.

As Politico reported, Alptekin has also worked closely with Ukraine-born businessman Dmitri “David” Zaikan to coordinate Turkish lobbying efforts in Washington, D.C., and both men have negotiated business deals with Vladimir Putin’s government (The two men denied knowing each other). Alptekin has criticized Russia’s recent imposition on the borders of other sovereign nations, however, accusing the Kremlin of “trying to adopt a political stance imitating the Soviet Union.”

What brought Alptekin to Flynn was his role in yet another business: Inovo BV, a Dutch-based company Alptekin owns.

In August, one month after Turkey’s failed coup, Inovo BV hired Flynn Intel Group to perform research and disseminate negative information about Fetullah Gulen, a Muslim cleric who Erdogan believes orchestrated the effort to unseat him from the Pennsylvania compound where Gulen lives in exile.

As part of its work with Inovo BV, Flynn Intel Group registered as a domestic lobbying entity and Flynn reportedly met with senior Turkish government officials about bypassing the U.S. extradition process to forcibly transport Gulen to Turkey—all while serving as a senior campaign adviser to Trump and sitting in on classified national security briefings. Flynn also published a fiery op-ed in The Hill on Election Day condemning the United States for harboring a “radical cleric” like Gulen, which tipped the Justice Department off to the potentially troubling nature of his lobbying.

After Flynn left office for lying to Vice President Mike Pence and others about his contacts with Russian officials, he retroactively registered with DOJ as a foreign agent for his work for Alptekin.

According to the Wall Street Journal, federal investigators are now looking into whether Flynn’s sizable contract “played any role in his decisions as the president’s adviser,” including his reported move to block a U.S. military operation against ISIS that Turkey opposed.

Flynn and Alptekin have characterized their work together quite differently.

Alptekin told ABC News this week that he has “never represented the government of Turkey” and that reports implying “that I was in any way representing the government are simply not true.”

By contrast, Flynn’s filings under the Foreign Agents Registration Act say that his work for Inovo “could be construed to have principally benefitted the Republic of Turkey.”

Alptekin seems well aware of the powerful weight lobbyists carry in Washington, telling the Centre for Policy and Research on Turkey last year that working with think tanks and “engaging in lobbying activities” was key to gaining influence in American politics.

With or without Flynn, he seems intent on continuing his crusade to extradite Gulen—who he insisted the United States must “stop tolerating” in his Monday speech at the Trump International Hotel—and to burnish the reputation of Erdogan, who he has heavily praised, on Capitol Hill.

Rahman, the Turkish GW professor, predicts Alptekin will have an easier time of achieving his goals under Trump than he did under Barack Obama. Trump’s decision not to address human rights during a speech in Saudi Arabia this week and his warm outreach to strongman leaders sends a “green light” to politicians like Erdogan, she said, as well as a simple message: “You have us as allies; manage your own house.”