American astronomer and author who in 1986 started a year tracking a hacker in California's Lawrence Berkeley Laboratory's computers which led to discovery of the intruder's effort to attempt espionage on linked computers of military and defense contractors. Eventually, the hacker was traced to West Germany, where he was arrested as part of a spy ring trading secrets to the Soviet KGB. His book about the quest to expose the criminal, Cuckoo's Egg: Tracking a Spy Through the Maze of Computer Espionage (1989), was a best-seller, which he followed with two more titles on computer technology.