David Benjamin Schrooten, known in the hacking world as 'Fortezza', was picked up in Romania in March before being handed over to US authorities. Appearing in a Seattle court on a 14 count indictment charging him with crimes including bank fraud and aggravated ID theft, he pleaded not guilty.

Schrooten is accused of running a scam with US citizen Christopher Schroebel, who was arrested in November and pleaded guilty last month.

Schroebel hacked into the point of sale computer in a restaurant in Seattle, and a supply store in Shoreline, Washington and inserted malicious code that copied the personal information of the credit card transactions at POS terminals.

The code transmitted the information to a Kansas server controlled by Schroebel who then worked with Schrooten to build carding sites where the data was sold, say the indictments.

US Attorney Jenny A. Durkan says that in just one transaction Schrooten trafficked in as many as 44,000 stolen credit card numbers resulting in millions of dollars in losses to financial institutions.