Who killed Magi?

The Journal de Montréal advances a theory that Tony Magi was killed by some ally of the Rizzutos because Nick Jr. was killed in 2009, possibly by Magi sidekick Ducarme Joseph, gunned down in turn in 2014. The Gazette has a timeline of the association between Magi and the Rizzutos; Kristian Gravenor also has some background as does Vice.