Adrian-Tiberiu Oprea, 29, of Constanta, Romania, recently pleaded guilty to one count of conspiracy to commit computer fraud, one count of conspiracy to commit wire fraud, and two counts of conspiracy to commit access device fraud, in connection with a scheme to steal the payment card data of more than 100,000 people from several U.S. merchants, including Subway restaurants (h/t Softpedia).

Oprea admitted having conspired with co-defendants Iulian Dolan and Cezar Butu to hack into hundreds of U.S.-based point of sale (POS) systems to steal payment card data from approximately 2009 to 2011. He apparently identified vulnerable POS systems via the Internet, then installed keylogging software on those systems to collect payment card data. He then attempted to use that data to make unauthorized charges or to transfer funds.

Dolan and Butu have already pleaded guilty. As part of his plea agreement, Dolan agreed to serve seven years in prison, and Butu has been sentenced to serve 21 months in prison.