In this April 25, 2006, file photo, John Durham speaks to reporters on the steps of U.S. District Court in New Haven, Conn.
The Justice Department's probe into its investigation of whether Russia interfered in the 2016 U.S. presidential election has shifted from an administrative review into a criminal investigation.
The New York Times was the first to report the development Thursday, citing two sources.
The new move gives the lead prosecutor the ability to issue subpoenas and empanel a grand jury.
It was not immediately clear if a grand jury has already been assembled.
John Durham, the U.S. attorney for Connecticut, is the lead prosecutor in the criminal investigation.
Special Counsel Robert Mueller concluded earlier this year in his report on possible Russian interference that there was not enough evidence to determine that President Donald Trump or his campaign colluded with Russia.
Mueller wrote, however, that he could not exonerate Trump of allegations of obstruction of justice, turning the matter over to Attorney General William Barr.
Barr said he could find no evidence of obstruction.
Trump has repeatedly characterized the Justice Department's initial Russia investigation as a "witch hunt."