WASHINGTON ― Robert Mueller on Wednesday encouraged Americans to read his special counsel report on Russian interference in the 2016 election and reiterated his office’s position that, while President Donald Trump could not be charged with a crime while in office, that doesn’t amount to an exoneration.

“If we had confidence that the president clearly did not commit a crime, we would have said that,” Mueller said at a press conference at Justice Department headquarters in which he also announced his resignation. “A President cannot be charged with a federal crime while he is in office. That is unconstitutional. ... Charging the President with a crime was therefore not an option we could consider.”

Mueller’s remarks alluded to impeachment, saying that the U.S. Constitution “requires a process other than the criminal justice system to formally accuse a sitting president of wrongdoing.” Mueller said his office was “guided by principles of fairness” and that it “would be unfair to potentially accuse somebody of a crime when there can be no court resolution of an actual charge.”

Mueller said his office “will not comment on any other conclusions or hypotheticals about the president” given its decision not to reach a traditional prosecutorial decision about Trump’s conduct.

Mueller’s press conference on Wednesday marked his first public statement about the special counsel’s investigation since it began two years ago. He announced that he was formally closing the special counsel’s office and that he was resigning from the Justice Department to return to private life.

While House Democrats have called for Mueller to testify before Congress, the former FBI director said he does not expect to speak publicly about the investigation again.

“I hope and expect this to be the only time that I will speak about this matter. I am making that decision myself — no one has told me whether I can or should testify or speak further about this matter,” Mueller said.

“The report is my testimony. I would not provide information beyond that which is already public in any appearance before Congress,” Mueller stated.

Mueller’s investigation did not find clear evidence to charge members of the Trump campaign with conspiring with Russian operatives to sway the election. Mueller chose not to reach a traditional prosecutorial decision on obstruction of justice, but he outlined 10 instances of potential obstruction by the president during the probe.

Attorney General William Barr and then-Deputy Attorney General Rod Rosenstein chose not to charge Trump with obstruction, a decision influenced by the Justice Department’s position that the president can’t be charged with a crime. Barr and Mueller previously privately sparred over a misleading letter Barr sent to Congress that failed to fully summarize the Mueller report’s findings.

Mueller ended his remarks by emphasizing that the Russian government did, in fact, interfere in the 2016 election.

“I will close by reiterating the central allegation of our indictments — that there were multiple, systematic efforts to interfere in our election,” Mueller said. “That allegation deserves the attention of every American.”