So my first thought here would be Invader, as being a vegan in charge of raising and killing pigs for sausage seems like an odd choice. A convenient cover story for disposing of the Mafia's victims, perhaps? Even if it is, though, I can't say Invader is the most likely culprit for this case. The body was found in the meat and the cranberry pie, meaning that the culprit would need more than access to the meat.
This brings me to my most likely candidate: Leoxander. That's right, I'm jumping on the bandwagon, but that's because I feel like it's a sound train of logic. How could the mafia have snuck these things into the meals without him noticing? Because he's the one who did it.
Now, I have to admit that there is some evidence that makes me wary of Jakanader. As Whaddon mentioned earlier, the appearance of salmonella after the body was discovered could imply that he had forgone his usual job in favor of disposing of the body. However, I'm not that knowledgeable about salmonella, and my first thought had been that the disease had simply occurred from the presence of human body parts in the food. He's suspect, but less likely than Leo, in my opinion.
Just to round things out, I doubt it was Racie. Being the first to arrive gives her opportunity to have slipped the body into the food, but her obsessive cleanliness seems to imply that this wouldn't be her MO.
So yeah, I vote for Leoxandar.