Giovanni Strangio, alleged to have shot dead six Italian men in cold blood with an accomplice as part of a 'Ndrangheta feud, was captured in a joint effort between German authorities and their Dutch and Italian colleagues.
Police had already arrested the Strangio's brother-in-law, Giuseppe Nirta, in Amsterdam in November 2008.
“They led a completely normal life there, mixing with the population and disguising themselves often with hats and glasses,” said Italian police officer Renato Cortese.
The murders, which shocked the Ruhr city of Duisburg the year before, were supposedly part of a dispute within the Calabrian mafia organisation.
Police said they would hold a press conference with more details later on Friday.