Who shot Johnny Torrio? Was Al Capone behind the Torrio hit in HBO's Boardwalk Empire?

In Boardwalk Empire, gangster Johnny Torrio is shot as revenge for the killing of Dean O'Banion, but there are clues in the show that point to Al Capone being behind the hit attempt. So lets analyse the show in this video essay and see if we can answer the question - Who really shot Johnny Torrio?