From Halflife2.net:
June, 10 2004 – Arrests have been made in several countries related to the break-in to Valve’s network, theft of the Half-Life 2 source code, and release of the source code on the Internet.
“Within a few days of the announcement of the break-in, the online gaming community had tracked down those involved,” said Gabe Newell, Valve’s CEO. “It was extraordinary to watch how quickly and how cleverly gamers were able to unravel what are traditionally unsolvable problems for law enforcement related to this kind of cyber-crime.”
Thousands of tips were received related to the criminal activities, with a core group of people who were able to analyze and backtrack from these clues. Subsequent to these individuals being identified, Valve has been working with various national authorities to prepare cases against those involved, leading to these arrests.
“It was very uplifting to see how the community rallied and tracked these people down. Everyone here at Valve is once again reminded of how much we owe to the gaming community,” added Mr. Newell.