According to the Santa Clara District Attorney's office, Andrew Madrid, 34, used his IT experience to pull off a variety of crimes between September 2006 and March 2008.

"This was one of the most sophisticated computer crimes our office has prosecuted," said Ben Field, Santa Clara's deputy district attorney. "There's computer intrusion in the first place, there's the introduction of spyware, there's the theft of proprietary data from a computer network, and sometimes the destruction of proprietary data from a computer network."

One of Madrid's victims was his former employer, a Sunnyvale, California, high-technology company. According to Field, Madrid destroyed data on the company's servers in the hope that "they would ask him to come back and fix the very problem that he created."

The Santa Clara District Attorney's office declined to name any of the victims of Madrid's crimes.

To make his hacking harder to trace, Madrid would often use his neighbor's open wireless networks, Field said.