Preet Bharara was fired while his office was reaching out to witnesses in an investigation into one of President Donald Trump’s favorite news outlets, Fox News, New York Magazine reports.

Bharara, the former U.S. attorney for the Southern District of New York, was in charge of a probe to determine if Fox News had hidden from shareholders payments to settle sexual harassment complaints against ousted news chief Roger Ailes, CNN Money and The New York Daily News reported last month. Both Ailes and Fox owner Rupert Murdoch are close friends of Trump. Fox News told CNN then that investigators from Bharara’s office had been in touch, but Fox would not confirm that the company was the target of a probe.

Sources have now told New York Magazine in a report Sunday that prosecutors in Bharara’s office were offering immunity to witnesses in the Fox probe in exchange for testifying before a federal grand jury that had already been impaneled. Investigators are probing not only possible mail and wire violations linked to shareholder information, but also whether Fox executives may have illegally obtained journalists’ phone records, according to the magazine’s sources.

Attorney Judd Bernstein told the Daily News last month that one of his clients, who was suing Fox and Ailes, had received a subpoena to testify from Bharara’s office relating to “alleged violations of criminal law by Fox.”

Lawyers being considered to replace Bharara include Ailes’ attorney, Marc Mukasey, who works in the same law office as Rudy Giuliani, The New York Times reported.

Bharara was directing a number of significant cases when he was summarily dismissed Saturday, including a probe into campaign fundraising by New York City Mayor Bill de Blasio (D), and an investigation into bribery and bid-rigging allegedly involving former associates of New York Gov. Andrew Cuomo (D).

In addition, ethics watchdogs from four nonprofit organizations sent Bharara a letter last Wednesday asking him to investigate whether Trump’s company, the Trump Organization, or any of his related companies “are receiving payments and financial benefits from foreign governments that benefit President Donald Trump” and do not comply with the emoluments clause of the Constitution.

The president had asked Bharara to stay on in November, then changed his mind last week. Bharara and 45 other federal prosecutors appointed by the Obama administration were asked to resign on Friday, a request that is standard practice when a new administration begins. However, when Bharara refused, he was fired on Saturday by Acting Deputy Attorney General Dana Boente on behalf of the president, CNN reported.

Acting deputy Attorney General Dana Boente just called US Attorney Preet Bharara and told him President Trump was firing him. — Jake Tapper (@jaketapper) March 11, 2017

I did not resign. Moments ago I was fired. Being the US Attorney in SDNY will forever be the greatest honor of my professional life. — Preet Bharara (@PreetBharara) March 11, 2017

Rep. Elijah Cummings (D-Md.), the ranking member of the House Oversight and Government Reform Committee, raised concerns Sunday that Bharara’s firing may have been motivated by Trump’s self-interest.

“There’s a lot of questions coming up as to whether ... President Trump is concerned about the jurisdiction of this U.S. attorney and whether that might affect his future,” Cummings said.

Trump reportedly tried to reach Bharara by phone on Thursday. Bharara instead called Attorney General Jeff Sessions’ office to say it was inappropriate for the president to be contacting U.S. attorneys, “particularly ones that have jurisdictions over important matters,” a source told The Wall Street Journal.

Bharara himself hinted at something nefarious in his firing, referring to the Moreland Commission in a tweet. The commission, which was dissolved in 2014, investigated corruption in New York’s political system in 2013.

By the way, now I know what the Moreland Commission must have felt like. — Preet Bharara (@PreetBharara) March 12, 2017

A White House aide told The Wall Street Journal Sunday that Bharara was treated no differently than the other 45 federal prosecutors let go.