experiencing team mueller up close is no walk in the park. >> it's intense. you know, first of all they ask to pick you up at a nearby hotel because they want to sneak you in the back door. that's the way they want to drop you off as well when you're done. it's also not a friendly environment. they're professional, i wouldn't call them impolite. >> reporter: but they are well informed. >> they know more about the trump campaign than any single person that worked there. that's because they have the documents. the mueller investigation knows more than one person does and anyone who sits with them needs to be mindful of that. >> reporter: especially the president as he and his team of revolving lawyers are aware. what would trump risk if he testified in front of bob mueller? >> untruthfulness and the possibly charge of lying to a federal investigator. >> at the end of the day is it a perjury trap or not? from my perspective the president shouldn't go anywhere