Computer security expert Tsutomu Shimomura and reporter John Markoff. Markoff writes about computers and technology for the New York Times. The two have collaborated on a new book, "Takedown: The Pursuit and Capture of Kevin Mitnick, America's Most Wanted Computer Outlaw-By the Man Who Did It." (Hyperion). Mitnick was the most wanted computer hacker in the world, having stolen thousands of data files, and 20,000 credit card numbers. For two years he had eluded the FBI. Mitnick broke into Shimomura's home computer, and Shimomura joined the search.