Even with Bahry obliviated there should be lots of clues it was Harry. Especially now that Quirrell is down and whatever spells he was casting to confound the wizarding equivalent of forensics are probably down. Harry sized foot prints in the dust, cloth fibers where Harry lay down? The angle/position that the stunning spell hit Bahry implying it was cast from a low elevation?

The wizarding world doesn't stoop to non-magical forensics. Footprints? Fibers? How barbaric.