I'm not an expert, so please correct me if I am wrong about any of the details.
39 Juventus fans are crushed to death by Liverpool fans. The latter, many years later, then do this: http://upload.wikimedia.org/wikipedia/commons/b/b3/Amicizia.jpg (it means "Friendship" in Italian.
Now would it be ok for the Police to make a mosaic saying "Alright, Alright, Calm down"? I don't think it'd be appropriate, maybe a bit presumptuous towards being greeted with open arms as well.