The FBI, the Slovenian Criminal Police and the Spanish Guardia Civil announced the arrest of the suspected creator of the Mariposa Botnet used by hackers worldwide.

Last week, the Slovenian Criminal Police arrested the Mariposa Botnet’s suspected creator, a 23-year-old Slovenian known as "Iserdo."

The Mariposa Botnet was built with a computer virus known as "Butterfly Bot" and was used to steal passwords for websites and financial institutions. It stole computer users’ credit card and bank account information, launched denial of service attacks, and spread viruses. Industry experts estimated the Mariposa Botnet may have infected as many as 8 million to 12 million computers.

"In the last two years, the software used to create the Mariposa botnet was sold to hundreds of other criminals, making it one of the most notorious in the world," said FBI Director Robert S. Mueller, III.

"These cyber intrusions, thefts, and frauds undermine the integrity of the Internet and the businesses that rely on it; they also threaten the privacy and pocketbooks of all who use the Internet."

In February, the Spanish Guardia Civil arrested three suspected Mariposa Botnet operators: "Netkairo," "Jonyloleante," and "Ostiator," aka Florencio Carro Ruiz, Jonathan Pazos Rivera, and Juan Jose Bellido Rios. These individuals are being prosecuted in Spain for computer crimes.

The FBI said the case is significant because it targeted not only the operators of the botnet but also the creator of the malicious software that was used to build and operate it.