Answer by Jim Clemente:
In my opinion the most sophisticated crime ever committed is Stuxnet. Although it may have been sanctioned by the US or other Governments, it was certainly illegal in the target country. It's ultimate goal was to stealthily end Iran's nuclear weapon development program, in order to do that, it had to infect pretty much every computer and electronic device around the world. Once the virus was released it began jumping from infected system to infected system until it eventually found the Siemens Step7 software that drives the centrifuges used in Iran's program. In all other systems, it simply sits there dormant and non-threatening. But in the Seimens centrifuges, it accelerated them until they burned themselves out and destroyed their systems. The really insidious component of this process was that it sent signals to the control panel that indicated the systems were functioning properly. Therefore, even while their systems were burning out, no one knew they were under attack.
Based on the scope of the viral infection and the sophistication of the attack, I believe Stuxnet is the most sophisticated crime ever committed– albeit for a good cause.