here is your star witness. he's in an interesting location within the trial. it's mostly a paper case. i guess this means you've got to end strong. you've got to have a great closer and wrap it all up for the members of that jury. >> the most important thing you can do as a prosecutor when you're putting on a cooperating witness, you know they're going to take some damage. you know the defense is going to score some points on them. you have to be able to rally back with corroboration, independence evidence that backs up the corroborator, so you're not just saying to the jury, take this criminal's word for it. what we've seen so far, the mueller team has done a great job of doing that. all the witnesses leading up to rick gates, the accountant, the bookkeeper, the vendors, have had a common theme of, man aenforcememanafort knew where every dollar went.