FILE PHOTO: Special Counsel Robert Mueller departs after briefing the U.S. House Intelligence Committee on his investigation of potential collusion between Russia and the Trump campaign on Capitol Hill in Washington, U.S., June 20, 2017. REUTERS/Aaron P. Bernstein/File Photo

WASHINGTON (Reuters) - Special Counsel Robert Mueller informed top U.S. Justice Department officials three weeks ago that he would not be reaching a conclusion on whether President Donald Trump had obstructed justice during the probe into Russian interference in the 2016 election, a U.S. Justice official said Monday.

The decision by Mueller not to reach a determination was “unexpected,” the person added, speaking anonymously in order to discuss private conversations involving U.S. Attorney General William Barr and Deputy Attorney General Rod Rosenstein, who received the news.