Michael Cohen, President Donald Trump's former attorney, has spoken with special counsel Robert Mueller's team several times over the past month, ABC News reported Thursday.
The report said the special counsel team has focused primarily on Trump's dealings with Russia. Investigators were also interested in whether Trump or Trump's associates discussed the possibility of a pardon for Cohen.
ABC said Cohen participated in the interviews without a guarantee of leniency for himself.
Cohen is also cooperating with a probe from New York state into the Trump family charity and the Trump Organization, CNN has reported, and he and his attorney met with state tax department officials last week.
Lanny Davis, attorney for Cohen, declined to comment. Peter Carr, a spokesman for the special counsel's office, also declined to comment, as did the office of the US Attorney for the Southern District of New York.
Cohen pleaded guilty on eight criminal counts last month and implicated Trump personally in campaign finance violations related to the paying of two women who have alleged they had affairs with Trump. The President has denied those allegations.
The reported cooperation of Cohen with the Mueller probe marked the latest instance of a Trump associate being said to work with the investigation the President has regularly railed against as a "witch hunt."
A federal judge said on Wednesday he was setting a sentencing date for Michael Flynn, Trump's former national security adviser, who pleaded guilty last year to lying to investigators and agreed to cooperate with the special counsel. Trump's former campaign chairman, Paul Manafort, has also pleaded guilty to several federal crimes and agreed to cooperate with Mueller's investigation.