Internet site that let users change real money for digital currency has been shut down by USA's Department of Justice (DOJ). site, called Liberty Reserve.com, was place for criminals around world to launder money. Money laundering is when "dirty cash" from drugs, robberies, etc. is changed into "clean money" that crime gangs can use. Criminals laundered (changed) more than $6 billion using Liberty Reserve. Police are investigating locations in 17 countries and have taken away dozens of computers and hard disk drives. They hope these can help them find out more about how Liberty Reserve operated. The DOJ says this is largest case of money laundering ever. Liberty Reserve.com looked like website for people to change dollars, euro and other currencies into digital money. Owners of other digital cash sites say this system makes it easier and cheaper to transfer money around world. However, DOJ says Liberty Reserve was started with main purpose of laundering money. It says website was designed, "to help criminals conduct illegal transactions and launder proceeds of their crimes". It added site was, "a financial hub of cyber crime world" that allowed credit card theft, investment fraud, hacking, child pornography and drug trafficking. Many honest people who used Liberty Reserve are now worried they have lost their money.