A Slovenian court on Monday sentenced to 58 months in jail Matjaz Skorjanc, the creator of the "Mariposa Botnet", a vast network of virus-infected computers used by criminal hackers.
Skorjanc was found guilty of "creating a malicious computer programme for hacking information systems, assisting in wrongdoings and money laundering", the Maribor regional court said.
It also ordered him to pay 3,000 euros (S$5,200)along with the expropriation of an apartment and a car that Skorjanc had bought with the money he earned by selling the computer virus to a Spanish crime group.
Skorjanc, a 27-year-old former medicine student, was arrested in 2010 in a joint two-year-long operation carried out by the United States' FBI with the Spanish and the Slovenian police.
At the time of Skorjanc's arrest, the FBI said the Mariposa Botnet could have infected as many as eight to 12 million computers around the world in homes, universities, banks, government agencies and companies.
A botnet is a network of malware-infected computers that can be controlled remotely and used to carry out attacks or other operations.
The Mariposa Botnet was designed to steal credit card data, online banking passwords, account information for social networking sites and other sensitive information.
It was also used to spread viruses and launch denial of service attacks, in which a website's servers are overwhelmed by simultaneous visits from infected computers.
Both the prosecution, which had demanded a seven-and-a-half-year prison sentence, and Skorjanc's defence, who maintain their client's innocence, have said they would appeal the court's decision.