The Justice Department's investigation into the Fox News Network now includes a federal law enforcement agency within the United States Postal Service that typically handles mail and wire fraud cases, according to news reports Thursday.
Financial crimes experts in the United States Postal Inspection Service have been added, four sources involved in the probe told CNN Money's Brian Stelter.
Investigators from both agencies have been interviewing former Fox News staffers and others "to obtain more information about the network's managers and business practices," Stelter reported.
Representatives of both the Justice Department and USPIS had no comment, according to the report.
Fox News' parent, 21st Century Fox, also declined to comment.
News of the Justice Department's investigation first surfaced in February – and Fox officials said then none of its operations had been subpoenaed.
"We have been in communication with the U.S. Attorney's office for months — we have and will continue to cooperate on all inquiries with any interested authorities," a spokeswoman said at the time.
That inquiry was reportedly focused on legal settlements with women who had alleged they had been sexually harassed by former Fox News Chairman and CEO Roger Ailes, who resigned last July after former anchor Gretchen Carlson filed a lawsuit on similar allegations.
The Justice Department's probe focused on whether Fox was required to inform shareholders about the settlements, Stelter reported.
Ailes, 76, who remains a Fox News consultant through next year, has denied the allegations.
The questions now being asked by investigations include "how the shareholder money was spent; who knew; and who should have known," one source told Stelter on Thursday.
However, new concerns are being raised about possible misconduct by Fox News employees and regarding the network's overall culture and environment, according to the report.
Questions are also surrounding those who served as confidants of Ailes, generally known inside the network as "friends of Roger," Stelter reported.
These consultants were employed by Ailes for various reasons – and at least one was paid $10,000 a month solely by submitting a monthly invoice to Fox, according to CNN Money.
Many of them left after Ailes' departure, however, sources told Stelter last August.
The Justice Department's investigation was being conducted by U.S. Attorney's Office for the Southern District of New York, Judd Burstein, an attorney for some of Ailes' accusers, told CNN Money in February.
Until March, U.S. Attorney Preet Bharara headed the office.
He was fired then by President Donald Trump after he refused to resign. Bharara, 48, had been appointed in 2009 by President Barack Obama.
"I'm not talking about any investigations that may or may not" have taken place, he told CNN Money this week when asked about any Fox News investigation.