Who Done it?

[Carnimírië]

My brother is reading LotR for the first time, and he asked me who raided the Prancing Pony, Bill Ferny and co. or the Black Riders? I had always assumed it was the Black Riders, I'm not sure why, but some time ago I read on some Tolkien forum that it could have been Bill Ferny. Now I think it's most logical that the latter is true, because of what Aragorn tells the hobbits the night before the attack, and my brother pointed out that the Riders would have sensed the Ring and wouldn't have been foiled so easily. So I thought I'd ask the people of the Downs. Any ideas, long-lost Letters, obscure HoMe references , or educated guesses would be appreciated.