these absences. >> we don't know what we don't know. >> why is it so important that witnesses cooperate and tell the truth in an investigation like this? >> because the testimony of the witnesses goes to the heart of any criminal case you have. >> thank you, and i yield back, thank you, director mueller. >> miss stephanic. >> mr. mueller, as special counsel did you review documents related to the origin of the counter intelligence investigation to the trump campaign? >> on occasion. >> was the steele dossier one of those documents reviewed? >> i can't discuss that case. >> i'm asking a process question, have you read the steele dossier. >> i'm not going to respond to that. >> you were tasked to investigate whether there was collusion between russia and the trump campaign to interfere with the 2016 election, and the fbi we know has relevant documents and information relating to the opening of the cia having.