User blog comment:Morganaforever/Morgana's torturer in 5x08/@comment-5204542-20121120170143

Spoiler Tv have updated their teasers and revealed that Sarrum said it.

“At night you could hear its cries; they were even more heart breaking than Morgana” Sarrum to ?

I still reckon Sarrum is the person who captured Morgana. Especially as he heard Aithusa's heartbreaking cries.