NEW YORK (CBSNewYork/AP)A federal corruption probe into NYPD officials has been expanded to investigate the fundraising activities of Mayor Bill de Blasio, sources said Friday.

As CBS2 Political Reporter Marcia Kramer reported, the expansion of the probe in some ways seems like a natural offshoot of the initial corruption investigation.

The corruption probe by the FBI and U.S. Attorney Preet Bharara is looking into whether polices officers accepted lavish gifts and vacations in exchange for police escorts and security.

But the investigation also involves businessmen Jeremy Reichberg and Jona Rechnitz, who both served on de Blasio’s inaugural committee in 2013 and contributed to his campaign.

Now, sources told Kramer the feds are questioning people in the real estate industry about how the mayor raises money.

Sources said the questions from the U.S. Attorney’s office have focused on how donations are solicited by team de Blasio – including former campaign treasurer Ross Offinger.

Reichberg and Rechnitz’s phones were tapped as investigators looked at their ties to former NYPD Chief of Department Philip Banks.

Rechnitz and his wife gave $9,000 to de Blasio’s 2013 campaign. He also gave $50,000 to de Blasio’s controversial nonprofit Campaign for One New York, which was used to raise money for his initiatives, Kramer reported.

Rechnitz further ponied up $102,000 when de Blasio asked for help to get Democrats to take control of the New York State Senate, Kramer reported.

Reichberg hosted a Campaign for one New York fundraiser that netted $35,000, Kramer reported.

A de Blasio spokesman, Dan Levian, responded to the probe.

“We are fully confident that the campaign has conducted itself legally and appropriately at all times,” Levian said in a statement.

On Thursday, police Commissioner Bill Bratton removed four of his most senior men from their command posts.

Deputy Housing Chief Michael Harrington and Deputy Inspector James Grant, head of the Upper East Side’s 19th Precinct, have been stripped of their guns and badges, and transferred, Police Commissioner Bill Bratton announced Thursday. Deputy Chief Eric Rodriguez and Deputy Chief David Colon have also been transferred.

NYPD Officials Disciplined

(Top row) NYPD Deputy Inspector James Grant and Deputy Chief David Colon, and (bottom row) Deputy Chief Eric Rodriguez and Deputy Housing Chief Michael Harrington have been disciplined in a federal corruption investigation. (Credit: CBS2)

On Friday, officials revealed how far the four high-ranking officers fell.

Grant was demoted from commanding officer of the 19th Precinct to working a desk in the medical division, while Harrington went from executive officer of the Brooklyn Housing Division to a desk job in Transit. Rodriguez was demoted as executive officer in Brooklyn South to handling fleet repairs and logging property confiscated during arrests, while Colon has gone from being commander of Brooklyn Housing to working in courts on such things as prisoner transfers.

“This is not a particularly good day for the department,” Bratton said on Thursday. “The public has expectations of its public officials, of its police department and certainly the leadership of the department. If those expectations are not met, actions must be taken.”

And now, all the digging into the NYPD has led investigators back to City Hall, Kramer reported.

Offinger, de Blasio’s former campaign treasurer, said he is “not allowed” to speak on record, Kramer reported.

A spokesman for the mayor said he has decided not to take any donations from the businessmen going forward. He said further that all funds from Rechnitz and his wife will be returned.

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