The multiple organizations that exist in a "mafia" specialize in particular types of crime
. Mafia is responsible for crimes like narcotics trafficking or smuggling, gambling, extortion, prostitution and also in hideous crimes like murders or assassinations as well as kidnappings. The organizations in the mafia that specialized in assassinations and killed anyone when ordered to became infamously known as "Murders Inc" among the media.
The mafia has not seized being in existence since long and with the passage of time they have just kept on growing in numbers and committing organized crimes.