A lengthy new investigative story in the New Yorker reveals that Donald Trump and his Trump Organization helped build a hotel in Baku, the capital of Azerbaijan, a project that the magazine says appears to be a corrupt operation, Trump’s “worst deal” ever and possibly a conduit for illegal activity by Iran’s Revolutionary Guard.

The 33-story luxury Trump International Hotel and Tower Baku, which never opened, was engineered by oligarchs, reporter Adam Davidson writes. It potentially violated the Foreign Corrupt Practices Act and may have enabled money-laundering and other illegal activities undertaken by the Iranian Revolutionary Guard.

The U.S. government has regularly accused the Guard of criminal activity, including drug trafficking, sponsoring terrorism abroad, and money laundering, Davidson added.

And while an attorney for the Trump Organization said that the president only played a “passive role” in the development of the property — merely a “licensor” who would allow his famous named to be slapped onto it — Davidson found, among other things, that daughter Ivanka Trump was a key player in moving the hotel project along. In fact, in her own words, she “oversaw” the project “since its inception.”

She was the most senior Trump organization official on the project, Davidson reported. One executive at a London-based construction firm involved in the project said he met with Ivanka on the project in Baku and New York and said “she had very strong feelings, not just about the design but about the back of the hotel — landscaping, everything.”

An Azerbaijani lawyer who worked on the project, and who said the Trump Organization was involved in more than just licensing the Trump name, said “Ivanka personally approved everything.”

A subcontractor told Davidson that Ivanka’s team “was particular about wood panelling.” The team chose an expensive Macassar ebony, from Indonesia, for the ceiling of the lobby. The ballroom doors were to be made of book-matched panels of walnut.

Ivanka wasn’t shy about boasting about her role in the project on her website, posting a photo of herself from November 2014, wearing a hard hat inside the half-completed hotel. A caption reads: “Ivanka has overseen the development of Trump International Hotel & Tower Baku since its inception, and she recently returned from a trip to the fascinating city in Azerbaijan to check in on the project’s progress.”

She boasted that the “ultra-luxury property …. will have thirty-three floors of expansive suites, guest rooms and residences with stunning views of the Caspian Sea.” She said the hotel was expected to open in 2015, but it never did.

The story describes much more about the operation, but here are some key points, outlined by Vox:

— For whatever reason, the Trump Organization chose to partner with an Azerbaijani businessman on a project that seemed like a dubious economic prospect from the start, given the project’s location in an “oddly unglamorous” part of the city and given that the partnership was announced in 2014, just when a construction boom in Baku had ended, Davidson said.

— “The Azerbaijanis behind the project were close relatives of Ziya Mammadov, the Transportation Minister and one of the country’s wealthiest and most powerful oligarchs,” the story reads.

— US diplomats have described Mammadov as “notoriously corrupt, even for Azerbaijan.”

— The Mammadov family also had close business ties with an Iranian-owned firm called Azarpassillo, and Davidson quotes an expert on Iran who says, “It looks like Azarpassillo is a front organization for the Revolutionary Guard.”

Davidson said no evidence has surfaced showing that Donald Trump, or any of his family or employees involved in the Baku deal actively participated in bribery, money laundering, or other illegal behavior.

But he says Trump’s business ties to this corrupt family should be investigated to determine if there were any violations of the Foreign Corrupt Practices Act.

Passed in 1997, the FCPA forbids American companies from participating in a scheme to reward a foreign government official in exchange for material benefit or preferential treatment, Davidson explained. “The law even makes it a crime for an American company to unknowingly benefit from a partner’s corruption if it could have discovered illicit activity but avoided doing so,” Davidson explains. “This closed what was known as the ‘head in the sand’ loophole.”

Because of the act, American companies must examine potential foreign partners carefully before making deals with them, according to experts Davidson consulted. To comply with the law, an American company must remain vigilant even after a contract is signed, monitoring its foreign partner to be sure that nobody involved is engaging in bribery or other improprieties.

Davidson also mentions several cases in which Americans were successfully prosecuted for violating the law, even after claiming ignorance of their foreign partner’s corruption. One involved the case of the co-founder of a handbag company which invested in a partner that paid bribes to Azerbaijani government officials and their family members. This handbag manufacturer was sentenced to a year in prison and lost his appeal after a U.S. Appeals Court ruled that he obviously was aware of how “pervasive corruption was in Azerbaijan.”

Davidson notes that Trump has been publicly critical of of the FCPA, saying it hurts American businesses trying to invest overseas. While Attorney General Jeff Sessions swore during his confirmation hearings that he was committed to upholding the act, it remains to be seen if Trump will try to overturn it.

Meanwhile, another key legal issue raised by the story is whether the Mammadovs’ association with Azarpassillo violates US sanctions against Iran, Vox notes.

On both issues, Davidson reports that the case so far is circumstantial. “The best way to determine if a crime was committed in the Baku deal would be a federal investigation, which could use the power of subpoena and international legal tools to obtain access to the contracts, the due diligence, internal e-mails, and financial documents,” he said.

The Department of Justice routinely sends investigators to other countries to pursue possible FCPA and sanctions violations, Davidson said.

He added that more than a dozen lawyers with experience in FCPA prosecution expressed surprise at the Trump Organization’s seemingly lax approach to vetting its foreign partners.

But, when Davidson said he asked a former Trump Organization executive if the Baku deal had seemed unusual, he laughed. “No deal there seems unusual, as long as a check is attached,” he said.