In their charges, prosecutors say Schroebel had in his possession 84,000 credit card numbers he had stolen or bought from other hackers. The two hackers operated "point of sale" operations, in which spy software is installed in computers used by businesses for transactions. The software records credit card numbers used.
Schroebel pleaded guilty in May to charges of bank fraud, obtaining information from a protected computer, access device fraud, among others.
Schrooten, who was arrested in Romania, is set to stand trial next month.