In Prisoner of Azkaban, there is a hint that "Scabbers" might not be dead ("Scabbers", aka. Wormtail, being the bad guy). After the Quidditch match, Harry asks Ron if he can just give the fight with Hermione a rest (remember, they think Crookshanks just ate Scabbers) and Ron says "No I can't. If she just acted like she was sorry - but she'll never admit she's wrong, Hermione. She's still acting like Scabbers has gone on vacation or something." Another instance of Ron accidentally finding the truth and not knowing it... Scabbers is on vacation in Hagrid's hut.


I do know this, the "culprit" in Chapter 13 isn't always the obvious person, and they themselves don't always show up... sometimes it's just a mention of them.