Fifteen years ago, Christy founded the Pentagon’s first digital forensics lab. Back then, most cops didn’t even bother to seize computers when they executed a search warrant. Ten years ago, he was the guy they tapped to explain computer security to senators and the White House. Now Christy has built his shop into the world’s largest center for pulling evidence off damaged or encrypted hard drives, tracking hackers across networks, reconstructing terrorists’ computers, and training a new generation of law enforcement. He’s the government’s original geek with a gun…