[ Hannibal follows Percy into his room in short order, and it's quite clear from how Hannibal is carrying himself that this is something important. He doesn't quite seem hurried or rushed, but there's purpose rather than the sort of gentle calm that he usually carries about himself. He glances to the door, and finding it seemingly satisfactorily shut, he steps further inside, slightly away from it. ]

I know one of our murderers. One of the ones that got away.

[ He's sure that will catch Percy's attention, which is why he's quick to qualify it: ]

That said, I do not know who they killed. Only that they did so.