The Justice Department plans to file criminal charges in the hacking of Donald Trump’s presidential campaign, two law enforcement officials told NBC News.

The FBI released a brief statement Monday that read, “We can confirm the FBI is investigating this matter.” The campaign provided no specific evidence of Iran’s involvement.

The FBI investigation has focused on an online persona named “Robert” who contacted American reporters, according to people familiar with the matter.

The charges would be the result of an FBI investigation into an intrusion that investigators across multiple agencies quickly linked to an Iranian effort to influence the U.S. presidential election.

U.S. authorities are preparing to file criminal charges after the Trump campaign said in August that some of its internal communications were hacked and blamed the Iranian government, the Washington Post reported on Thursday,