Also, I don't think it would be reasonable to have to find a solution to the question here. No one can say with 100 % certainty whether Chris was a rat or not. That is EXACTLY what Chase wants - if we knew Chris was a rat, then some might view Tony's killing of Chris as justified. If he wasn't a rat, Tony's killing becomes more horrifying. Yet, if we are left with a degree of uncertainty, we are left in Tony's point of view, as we are for most of the show. In season 6B, more than any other season (one could argue), everything is focused on developing our opinions of Tony. What Chase wants is to create an air of disgust and dislike in Tony Soprano. After all, he is a murderer and criminal.