NEW YORK (CBSNewYork) — A federal investigation was under way Tuesday into possible corruption in the NYPD.

As CBS2 Political Reporter Marcia Kramer reported, sources said it all started with an investigation of Norman Seabrook, the head of the city’s Corrections Union, and an investment he made of millions of dollars of union pension funds into hedge funds operated by local businessmen.

But sources said wiretaps of the businessmen’s phones caused the FBI and U.S. Attorney Preet Bharara to expand to the probe to include possible corruption in the NYPD.

The wiretaps turned up conversations about police officers.

“On these investigations, we’re not able to comment on them,” police Commissioner Bill Bratton said Tuesday. “It’s an agreement with the bureau.”

The probe has already led the NYPD to take the gun and badge away from a Community Affairs detective in the 66th Precinct in Brooklyn. He was put on desk duty after he took the Fifth Amendment in front of a grand jury.

“He has been placed on modified assignment for the good of the department,” Bratton said.

Sources said a number of police officers are being questioned as part of a probe into whether they received gifts and trips in exchange for undisclosed “favors.”

They include three deputy chiefs and the head of the 19th Precinct on the Upper East Side.

Roy Richter, head of the Captain’s Benevolent Association representing chiefs, told CBS2: “I am aware of a federal investigation… A number of my members have been interviewed by federal investigators. All of them fully cooperated.”

Kramer asked Bratton whether he is troubled by the fact that there is an investigation.

“It’s the nature of a business that always results, unfortunately, in investigations,” Bratton said. “We’ll just have to see where the investigation goes.”

Bratton said the NYPD will cooperate fully with the FBI and the U.S. Attorney.

Through a spokesman, Seabrook declined a request for an interview.