@EggCrusher, nothing was actually confirmed. A few people seem to think it was Solas, however.
Thanks! I wonder whether this implies that Solas did or didn't kill Felassan. I just can't picture it because Felassan seemed to like him. And it doesn't seem Solas' style.
I guess the only thing it implies is that there may actually be something to talk about post DLC. I've seen quite a few people jump to the conclusion that Solas was the one who iced Felassan. I'll be happy to admit I'm wrong if I am, but at the moment I'm thinking there might be a third party involved. Maybe Felassan has a boss who just wasn't as cool as Fen'Harel whom he told stories about instead. Or maybe he was actually working for/with Solas who actually did kill him. We have seen that Solas can kill people if he sets his mind to it (and a perceived betrayal might be something that would make him kill) and the developer notes implied this as well, but Gaider did tell us not to take them as fact. They have also stated the ways in which they softened Solas's character, though, so who knows.
I know I'd rather it be a dangerous third party though and Solas the red herring or something.
If I remember correctly there was a point where we discussed it in the thread. I think a lot of us wanted to blame Falon'Din after the codex about him. June, too (for no particular reason other than fun and the fact that not being talked about much is kind of suspicious).