Greenberg began talking to detectives when he realized this was his only path to leniency despite considerable evidence against him, people told the Times.
A source familiar with the case later confirmed to CNN on Tuesday that Greenberg has since provided investigators with information, including information about encounters he had with women who received cash or gifts in exchange for sex. Greenberg has met with researchers several times.
His partnership with the Justice Department could exert additional legal pressure on Gaetz, while investigators are investigating whether he himself violated sex trafficking or prostitution laws.
Gaetz has continued to deny all charges against him and has not been charged with any crimes.
The Florida Republican was on Capitol Hill on Tuesday to cast votes, but he did not comment on the New York Times report at the request of CNN.
A Gaetz spokesman, Harlan Hill, told CNN in a statement Tuesday evening that Gaetz “never paid for sex” and suggested that Greenberg is “trying to ensnare innocent people in his troubles.”
CNN has contacted Greenberg’s attorney for comment.
The former tax commissioner in Seminole County, Florida, and a friend of Gaetz, Greenberg had served decades in prison on 33 federal counts, ranging from identity theft to sex trafficking of a minor.
“We think this case will be a plea,” said assistant US attorney Roger Handberg. Greenberg’s attorney, Fritz Scheller, filed for a plea by May 15. If no plea is reached, they can go to trial in July.
After speaking to reporters at the hearing, Scheller declined to say whether his client would be willing to cooperate as part of the possible plea deal and would not reveal if Greenberg had already met prosecutors to describe what he knows about Gaetz .
However, he added that his client is ‘uniquely situated’.
“I’m sure Matt Gaetz isn’t very comfortable today,” said Scheller.
This story has been updated with additional reporting.
CNN’s Paula Reid, David Shortell, Mark Morales and Ryan Nobles contributed to this report.