Deutsche Bank’s relationship with President Trump has long interested Trump/Russia-watchers—and drew a barrage of new headlines after Michael Cohen, the president’s estranged ex-fixer, told Congress that Trump lied to the bank when trying to get a loan.

Since ending his years-long relationship with Trump last year, Cohen has said he is cooperating fully with federal law enforcement, including prosecutors in the powerful Southern District of New York.

But if investigators there pursue leads from Cohen related to the German financial institution, they could face a dilemma. That’s because the top two officials in the Southern District, U.S. Attorney Geoffrey Berman and deputy U.S. Attorney Robert Khuzami, have both done extensive legal work for the bank. The two men, who have worked for Trump’s lender of choice, now helm the U.S. attorney’s office that presents a major threat to Trump’s associates. Prosecutors there extracted a guilty plea from Michael Cohen over campaign finance violations he committed during the 2016 presidential campaign, and identified Trump as “Individual 1” in court documents—hinting he may have committed a felony. The designation goes further than anything Robert Mueller has said publicly about the president.

Khuzami’s relationship with the bank is public. He worked there from 2002 to 2009, ultimately becoming its general counsel for the Americas and handling its responses to investigations and litigation. The position gave him broad visibility into the bank’s thorniest conflicts. He left before bankers there carried out financial transactions known as mirror trades for wealthy Russian clients. Regulators in the U.S. and the U.K. concluded that the bank’s Russian clients used those mirror trades to launder $10 billion. They fined the bank $630 million for failing to stop the scheme.

Berman also represented Deutsche Bank and some of its top executives in legal matters. Bloomberg reported last year that Berman represented the bank and some of its executives while he was in private practice at the white-shoe firm Greenberg Traurig. A source familiar with Berman’s work on behalf of Deutsche Bank told The Daily Beast he did lots of legal work with the bank over the years, including representing some of its senior executives.

A review of media coverage indicates Berman has not publicly discussed his work for the bank. The bank declined to comment on Berman and Khuzami, and a spokesperson for the Southern District said the office “is in compliance with Department of Justice policy regarding recusals.” He is recused from the investigation that targeted Michael Cohen because of “a routine conflict of interest,” according to The New York Times.

Berman’s unorthodox ascent to the top of the Southern District may explain why his background has drawn surprisingly little public scrutiny; after firing dozens of U.S. attorneys, including Berman’s predecessor Preet Bharara, Trump installed Berman in the post in an interim capacity. Judges in the Southern District then formally installed him as U.S. Attorney. As a result, he has not been through the Senate confirmation process, where congressional staffers would have vetted him.

A source who has worked with both Khuzami and Berman, and who is not authorized to speak to media, said both are committed to ethical work.

“Both Geoff and Rob are top-flight lawyers with immense skill and judgment,” the source said. “I wouldn’t bet against either of them.”

Their histories with the bank could raise thorny questions for ethics experts.

“If in fact the Southern District investigation involves Deutsche Bank, then both the U.S. attorney and the deputy U.S. attorney will have to make difficult recusal decisions,” said Elie Honig, a former prosecutor in the Southern District. “Recusal is a complicated, fact-intensive inquiry, and it’s hard to say from a distance what the outcome should be. If they do both decide to recuse, then the current Criminal Division chief would presumably take over: Laura Birger, who is a very smart and independent and fair-minded prosecutor.”

It isn’t clear if prosecutors in the Southern District are looking at the relationships between the Trump Organization and Deutsche Bank. But those relationships are deep and thick. When most American lenders eschewed Trump because of his multiple bankruptcies and defaults, Deutsche had an open door for him. Bankers with the German institution saw lending to Trump as a way to get their foot in the door of the American financial services market, and their risk-friendly approach to investments made Trump an acceptable partner. But it didn’t always go well. A detailed New York Times investigation published this week sketches out the dramatic ups and downs of the relationship, including how Trump wooed bankers by promising them trips to Mar-a-Lago and that the sign-off on one Deutsche Bank document related to Trump turned out to be fraudulent.

Trump’s history with the bank has drawn pointed scrutiny from congressional investigators, including House intelligence committee Chairman Adam Schiff (D-CA) and House Financial Services Committee Chairwoman Maxine Waters (D-CA). Both have promised to dig into the relationship between the Deutsche and the president’s business. And the bank has said publicly that it is cooperating with the probes.

“The bank has received an inquiry from the House Financial Services and Intelligence Committees,” said a spokesperson in a statement provided to The Daily Beast. “Deutsche Bank is engaged in a productive dialogue with those Committees to determine the best and most appropriate way of assisting them in their official oversight functions. We remain committed to providing appropriate information to all authorized investigations.”