Ehh, this chapter was fairly predictable. The trick was interesting, but how would no one notice the broken glass? You wouldn’t get such a clean cut and glass would be everywhere.
Like Touma said, he was obsessed about the "shape" of his crime, that he desperately needed it to work out, he could've gotten away Scott free but his original plan was to involve one of the Goodmans to make it give him a "solid" escape and that didn't work out since it was blamed on an outsider robbery, so he had to rectify it because it bad to fit the "shape"I still don't understand why he couldn't just let the crime sit, though. Was he expecting to get caught eventually?