testify. i don't think that's legally correct. >> the argument comes amid a standoff with mueller's team over whether the president should sit for voluntary interview. >> we're demanding from him, tell us what you have to get in interview that you don't already have. >> at the one year mark, special counsel team brought charges against 22 people and companies, five guilty pleas, one person was sentenced. a number of the charges tied to russia's interference in the 2016 presidential election, but so far none of them extended to collusion between trump associates and the russians. despite the protests from the trump team. >> about time to get the darn thing over with. about time to say enough. we have tortured this president enough. >> there's little sign the investigation is wrapping up. early this morning, mueller arrived at his nondescript government office building. the team calls in witnesses covertly. inside, witnesses are questioned in rooms with mismatched furniture. michael caputo that met with the