An investigation into Fox News by the U.S. Justice Department has widened, with a second law enforcement agency joining the probe, according to a report today by CNN.

“Financial crimes experts from the United States Postal Inspection Service are now involved, according to four sources connected to the investigation,” the story reports. “Mail fraud and wire fraud cases are part of the USPIS purview.”

The report adds: “Investigators from both the USPIS and the Justice Department have been conducting interviews in recent weeks — including with some former Fox staffers — to obtain more information about the network’s managers and business practices, the sources said.”

The federal investigation first surfaced in  February, the report notes. “At the time Fox News and its parent company 21st Century Fox said they had not been subpoenaed, but a spokeswoman said, ‘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,'” CNN reports.

The key players — the Justice Department, the USPIS and 21st Century Fox — were not commenting for today’s story.

“In February the investigation was reported to be focusing on settlements made with women who alleged sexual harassment by former Fox News boss Roger Ailes, and questions about whether Fox had a duty to inform shareholders about the settlement payments,” CNN notes.

The report adds: “But, CNNMoney has learned, the settlement payments are not the only thing they are examining. Investigators have been probing possible misconduct by Fox News personnel and asking questions about the overall environment at the network.”