The German federation against copyright theft, GVU, has worked with the police to achieve the arrest a 46-year-old lawyer, two brothers and a teenager for allegedly selling illegal software, movies, games and music through a commercial online service.
The men had operated the high-speed e-commerce service in Germany from June 2003 to September 2004, GVU said.
More than 45,000 customers paid a monthly flat rate of €135 (£91.85) for the premium content, which was downloaded from servers located outside of Germany.
Damages are estimated to be in the millions of euros from lost revenue, GVU said.
The arrests come just four days after a German court sentenced a father and son to jail for copyright infringement and selling counterfeit Microsoft software.
John Blau writes for IDG News Service