[ He nods, squatting so he can look at the glass more closely - in particular, the green cloth with swirling patterns. Maybe something had been wrapped in it and hurled at the window? But then that object would still be here. Had someone punched the glass out then? ]

Putting aside what they used for the moment, if we assume the intruders broke the glass then how did it end up outside?

[ And furthermore, why? Blackquill hums quietly, eyes flicking to the interior as if it might provide further clues. ] Glass cannot fly on its own.