[Dog]

Could this have been a professional hit???

[Catspaw]

IMHO, it's less of a professional hit than it is an ideological hit, similar to the Unabomber. He--or they--are killing for a belief, no matter how twisted it is--rather than a paid hit.

[backhoe]

A real pro would probably be content with one head shot with a .22-- like organized crime in the States used to favor. The multiple shots with a heavy ( well, fairly ) calibre weapon argue towards and angry amatuer.