The New York Times is reporting that the U.S. Federal Bureau of Investigation opened a counterintelligence probe in 2017 into whether President Donald Trump was working for Russian interests.
The newspaper, citing unnamed former law enforcement officials and others, reported on January 11 that the counterintelligence investigation was initially separate from an ongoing criminal investigation.
The criminal probe had focused on interactions between Russian officials and Trump associates, and was originally in the summer of 2016, during the presidential election campaign.
The probe later expanded into whether Trump committed a felony crime of obstruction of justice when he fired FBI Director James Comey in May 2017.
Special Counsel Robert Mueller took over the FBI probe after Comey's firing.
According to the Times, FBI officials also opened a counterintelligence investigation around the time of Comey's firing, after officials were alarmed by comments Trump made suggesting Comey's firing was due to the original Russia investigation.
A counterintelligence investigation typically concerns national security matters, as opposed to criminal matters.
According to the paper, both lines of inquiry are now under Mueller's purview.
Mueller's probe has brought indictments against 34 people including Trump's former campaign chairman, Paul Manafort; Trump's first national security adviser, Michael Flynn, as well as a series of Russian intelligence officers and Kremlin-connected officials.
Trump and his allies have repeatedly criticized Mueller's investigation, calling it a "witch hunt" and questioning the political motivations of his investigators.
Recent news reports and court filings suggest that Mueller may be nearing the end of his investigation, at which point he is supposed to turn over a confidential final report to the Justice Department.
At least three different congressional committees, including the Senate Intelligence Committee, have also been probing various aspects of Russia's alleged interference in the 2016 election.
The U.S. intelligence community has concluded that Russia engaged in a campaign of hacking and propaganda to sway voters during the 2016 election, largely aimed at bolstering Trump's chances at the presidency.
Russian officials have repeatedly denied any such effort.