A New Zealand teenager was convicted on Tuesday due to his major role in a global cyber crime ring that managed to infect nearly 1.3 million computers worldwide and caused $20 million in losses. The investigation was launched after an assault involving 50,000 computers crashed the server at the University of Pennsylvania in the U.S. in 2006.

Owen Thor Walker, 18, was arrested as part of an FBI investigation in December. He pleaded guilty to six charges of using computers for illegal purposes and he will be sentenced in May. The charges are accessing a computer for dishonest purposes, interfering with computer systems, possession of software for committing crime and accessing computer systems without authorization, BBC News reports.

According to the New Zealand police officers, it seems that the teen started committing crimes at school. As the leader of the hacker’s group, he designed a unique encrypted virus that could not be detected by anti-virus software and made almost NZ$40,000 selling the program to other hackers. Walker was able to access usernames, passwords and credit card details.

The teenager, who used the online name “Akill”, is facing now with the possibility to remain in prison up to five years. He is due to be sentenced on May 28.

New Zealand police cooperated with the Federal Bureau of Investigation in the U.S. and with the Dutch authorities in order to reveal the network.

Symantec Corp. reported last year that China had the most infected computers at 29 percent. The U.S. at 13 percent followed the communist country. It seems that 43 percent of the servers used by hackers were located in the U.S., CNN reports.