The man believed to have created the Mariposa botnet which compromised millions of computers across the globe, has been denied bail.
Matjaž Škorjanc, believed by the authorities to be the hacker known as "Iserdo", was arrested in the city of Maribor, Slovenia, back in 2010.
The Mariposa botnet was brought down at the end of 2009, but at its peak, the botnet (named after the Spanish word for "butterfly") had hijacked almost 13 million computers in more than 190 countries.
The PCs had been silently commandeered by hackers after being infected by the polymorphic Rimecud family of malware, which spread via a variety of methods including removable storage devices, instant messaging and P2P file-sharing systems.
Once a computer had been compromised and brought into the botnet, operators could steal information from innocent users - including their credit card details and banking passwords.
According to the authorities, the Mariposa botnet's code was sold to hundreds of online criminals around the world.
Matjaž Škorjanc was denied bail of 61,000 Euros, and his trial will resume in May.