Former federal prosecutor Chuck Rosenberg believes there’s likely plenty in special counsel Robert Mueller’s report that’s damaging — and possibly criminal — regarding President Donald Trump. “It’s never taken me 400 pages to say nothing happened,” he added, referring to the reported length of the Mueller report.

Rosenberg, who was acting head of the Drug Enforcement Administration in the Obama and Trump administrations until September 2017, believes that, though crimes may have been committed by Trump, it’s likely Mueller didn’t believe he could file charges against him. It’s Justice Department policy not to indict a sitting president because it’s too “burdensome” and “stigmatizing,” he noted.

“I imagine something happened, and that something, particularly with respect to obstruction, was quite serious,” he said Monday on MSNBC’s “Deadline: White House.” “I can imagine Mueller not making a recommendation, because a recommendation to prosecute someone you can’t prosecute is equally burdensome and equally stigmatizing.” Rosenberg was chief of staff to FBI Director James Comey from 2013 to 2015.

Rosenberg added: “I don’t believe for a minute, if Mueller had facts that exonerated the president on obstruction, he would have hesitated to say so.” There may not be “a lot of evidence on the other side” that Trump didn’t obstruct justice, Rosenberg said.

“I imagine the facts ... [may] weigh heavily in favor of a prosecution — but for the fact that you can’t charge a sitting president,” he added.

Check out Rosenberg’s interview with Nicolle Wallace below. He talks about Mueller’s report beginning at 9:12.