the last supper painting

the last supper painting
Could that window have been closed and refastened after the flight of the assassin?" asked Rouletabille.
"That is what occurred to me for a moment; but it would imply an accomplice or accomplices, - and I don't see -"
After a short silence he added:
"Ah - if Mademoiselle Stangerson were only well enough to-day to be questioned!"
Rouletabille following up his thought, asked:
"And the attic? - There must be some opening to that?"
"Yes; there is a window, or rather skylight, in it, which, as it looks out towards the country, Monsieur Stangerson has had barred, like the rest of the windows. These bars, as in the other windows, have remained intact, and the blinds, which naturally open inwards, have not been unfastened. For the rest, we have not discovered anything to lead us to suspect that the murderer had passed through the attic."