SolidWorks, PTC, and Alibre are not the only companies to have suffered electronic attacks. I just came across this 2000 story involving Bricsnet USA:
Bricsnet had just suffered a massive attack over the Internet. Somebody had broken into its systems, erased customer files, modified financial records, and sent e-mail to Bricsnet's customers, announcing that the company was going out of business.
Within a week, Patrick McKenna was arrested and sentenced to six months in jail and restitution payment of US$13,614.11. He was a help desk worker who had been fired, launching his attack on Bricsnet later the same day.
You can read the full details at The FBI's Cybercrime Crackdown, which describes how the FBI attempts to track down cybercrime.