In most cases the mafia tried to dispose of the body as efficiently as possible. Without a body, conviction is a lot harder.

Dump in an incinerator, put in a car about to be crushed at the wrecker’s, 55 gallon drum willed with concrete and disposed at sea, put inside a casket that is about to be buried. Use a wood chipper, chop into little piece and down an industrial garbage disposer.

Sometimes, they want the body to be found as a warning.

La Cosa Nostra is creative.

Mostly what @zenvelo said unless they wanted to make a statement then they would leave it for all the world to see.

Sometimes we they want to send a message.
One time I
heard uh, somebody left a skimmer with a Benjamin in each hand.
Expensive , but effective.
I guess.
I heard.

When I worked at a funeral home, certain “troubleshooters” as they were called would bring in bodies for cremation. We didn’t share much information or ask questions, but one of the mobsters told me that the slop drains or waste deposits at a certain Truck Stop on I-40 near Lakeland was also used. There is lots of organic matter and chemicals that dissolve any evidences.

It is always safer for a person to simply vanish than to leave any evidence behind as an example of what happens to people who cross the mob.