Former FBI Director James Comey said Tuesday that he found it "confusing" that special counsel Robert Mueller decided not to determine whether President Trump was guilty of obstruction of justice.

"The part that's confusing is I can't quite understand what's going on with the obstruction stuff," Comey said to an audience at the Belk Theatre in Charlotte, N.C., according to NBC News.

"And I have great faith in Bob Mueller, but I just can't tell from the letter why didn't he decide these questions when the entire rationale for a special counsel is to make sure the politicals aren't making the key charging decisions," he added.

Comey was referring to the decision made by Attorney General William Barr and Deputy Attorney General Rod Rosenstein not to pursue charges against Trump related to obstruction of justice after Mueller declined to draw a conclusion on the matter.

"The notion that obstruction cases are somehow undermined by the absence of proof of an underlying crime, that is not my experience in 40 years of doing this, nor is it the Department of Justice's tradition. Obstruction crimes matter without regard to what you prove about the underlying crime," said Comey, who led the Russia probe before Trump fired him in May 2017.

He said he has not seen Mueller's final report.

Comey, who's been a staunch advocate for transparency in Mueller's investigation and conclusions, said he was pleased the special counsel was able to finish his work.

"The good part is that the special counsel was allowed to finish his work and reached a conclusion; that's very, very important to this country," Comey said. "The Russians really did massively interfere with the 2016 election with the goal of damaging one candidate and helping the other. That was not a hoax. That was a real thing."