The New York Times is reporting that FBI officials were so alarmed by President Donald Trump’s behavior after he fired former FBI Director James Comey that they started investigating whether he was working against American interests.

The Times cited anonymous former law enforcement officials and others familiar with the investigation Friday who said counterintelligence investigators looked into whether “Trump was knowingly working for Russia or had unwittingly fallen under Moscow’s influence.”

The officials told the newspaper that after Comey was fired in May 2107, they become concerned when Trump tied the firing of Comey to the Russia investigation.

Trump actions questioned

Law enforcement officials have previously confirmed that after the firing the FBI opened an investigation into whether the action constituted obstruction of justice. However, what has not been made public is that law enforcement officials also sought to determine whether the president’s own actions constituted a possible threat to national security, according to the Times.

The entire investigation was taken over several days later when special counsel Robert Mueller was appointed to investigate Russia’s attempts to influence the 2016 election as well as possible ties between Russia and the Trump campaign.

There has been no public evidence that Trump was in contact with Russia during the election campaign and Trump has long denied any illicit connection. Russia has also denied the allegations.

Giuliani: Nothing found

A lawyer for Trump, Rudolph Giuliani, told the Times that if FBI officials had concluded Trump was working against American interests, the public would have heard about it.

“The fact that it goes back a year and a half and nothing came of it that showed a breach of national security means they found nothing,” Giuliani told the paper.

Two days after Trump dismissed Comey in May 2017, he told NBC News anchor Lester Holt that he was going to fire Comey regardless, “knowing there was no good time to do it,” but was thinking of the Russia investigation when he decided to dismiss him.

“When I did this, now I said to myself, ‘You know, this Russia thing with Trump and Russia is a made-up story. It’s an excuse by Democrats for having lost an election that they should have won,’” Trump said.

Comey’s firing, rather than ending the Russia investigation, led directly to the appointment, over Trump’s objections, of Mueller, another former FBI director, to take over the Russia probe. Trump has repeatedly called the Russia probe a “witch hunt.”