BERLIN , Germany ( CNN ) -- Six Italian men were shot dead in the German city of Duisburg on Wednesday in an execution-style killing linked to a mafia feud . Police remove a body from the scene . Italian Interior Minister Giuliano Amato said the shootings appeared to be linked to a feud between two mafia clans in the southern region of Calabria , home to the 'Ndrangheta organized crime group . Here are some key facts about the group : . ORIGINS : . -- The Calabrian `` Honored Society '' , known as `` 'Ndrangheta '' , in the Calabria region of south Italy is the equivalent of the Sicilian Mafia . -- 'Ndrangheta began as a defense network for impoverished rural peasants against aristocratic landlords . Members emigrated to Canada and the United States , and were discovered running an intimidation scheme in Pennsylvania mining towns in 1906 . HOW DOES IT WORK ? -- They are known as `` The Honored Society '' , Fibbia or Calabrian mafia . Instead of the pyramid structure of bosses used by other mafia , The 'Ndrangheta '' uses families based on blood relationships , inter-marriages , or being a Godfather . Each group is named after their village , or after the family leader . TWENTIETH CENTURY EXPANSION : . -- When Calabria began the process of industrialization and urbanization in the late 20th century , the 'Ndrangheta became interested in drug trafficking , weapons sales and public works and construction . THE PRESENT : . -- In 2004 , authorities uncovered an international drugs trafficking network involving gangs in South America , Australia , and Europe . Drugs from Colombia were destined for countries such as Greece and Bulgaria . -- Italian officials estimated at the time that 80 percent of Europe 's cocaine had arrived from Colombia via Gioia Tauro 's docks in Reggio Calabria . -- Italian anti-organized crime agencies have estimated that the 'NDrangheta earns about $ 30 billion annually , mostly from illegal drugs , but also from ostensibly legal businesses such as construction , restaurants and supermarkets . -- There are believed to be about 100 'Ndrangheta families in Calabria , who have become more successful than their Sicilian counterparts because their family ties are closer . E-mail to a friend . Copyright 2007 Reuters . All rights reserved.This material may not be published , broadcast , rewritten , or redistributed .
Six young men found shot in the head in western German city of Duisburg . Five were dead when authorities arrived , two died later . The victims were between 15 and 18 years old , police say . Police believe the murders may be linked to organized crime in Italy .