There were probably quite a few people that probably wanted the Musitano's out of the way.
-The Papalia's or members of the clan, may have wanted to revenge. -The Luppino's would benefit;also if Ken Murdock is to be believed there was a plot by the Musitano's to have the Luppino's killed. Musitano's were emboldened by their close ties to Rizzuto's. -The Violi's for that same reason, their close ties to the Rizzuto.
Can anybody else come up with other possible theories?
This alleged book (memoir) that Angelo wrote.
Those three Italian crime groups in Hamilton have had a lot of interaction over many decades, including violence; the relationships have been very complicated--especially because members of the groups have worked or associated with one another even while hating one another. John Papalia was Pat Musitano's baptismal godfather, for example.
The Musitanos and the Luppinos even had respective low-level associates fight a proxy war in the 1980s: Tim and Tom Magnini were aligned with the Musitanos, and Luciano "Luch" Pietrorazio--a former leader of the Barton-Sherman gang in Hamilton--was an associate of Natale Luppino.
