Combining technical wizardry with the ages-old guile of a grifter, Kevin Mitnick is a computer programmer run amok. And law enforcement officials cannot seem to catch up with him.
As a teen-ager he used a computer and a modem to break into a North American Air Defense Command computer, foreshadowing the 1983 movie "War Games."
He gained control of three telephone company central offices in Manhattan and all the phone switching centers in California, giving him the ability to listen in on calls and pull pranks such as reprogramming the home phone of someone he did not like so that each time the phone was picked up, a recording asked for a deposit of 25 cents.
For months he secretly read the electronic mail of computer security officials at MCI Communications and Digital Equipment Corp., learning how their computers and phone equipment were protected. Officials at Digital later accused him of causing $4 million in damage to computer operations at the company and stealing $1 million of software.
Now law enforcement officials suspect that Mr. Mitnick, 30, one of the nation's most wanted computer criminals, is the person who stole software and data from more than half a dozen leading cellular telephone manufacturers, coaxing gullible employees into giving him passwords and computer codes that could be used to break into their computers. The companies plan to use the software for everything from handling billing information to scrambling wireless phone calls to keep them private.
Mr. Mitnick has eluded an FBI manhunt for more than a year and a half, Justice Department officials say. Last year, while a fugitive, he managed to gain control of a phone system in California that allowed him to wiretap the FBI agents who were searching for him.
"He has created a lot of frustration inside the bureau," said James Settle, a former computer crime fighter for the FBI. "He should have been locked up long ago."
Mr. Mitnick is adept at what is known in the computer underground as "social engineering." By masquerading as a company executive in a telephone call, he talks an unsuspecting company employee into giving him passwords and other information that makes it possible for him to gain entry to computers illegally.
Using a personal computer and a modem, he then connects to a company's computer and, with his knowledge of how operating systems work, commands it to copy software, display confidential electronic messages or alter a telephone switch so he can silently monitor a call.
There is no evidence that Mr. Mitnick has used his computer skills illegally to make money, although the cellular phone companies say the person who stole their software could sell it to competing manufacturers.
FBI and Justice Department officials said they were still uncertain of his motives and did not have absolute proof that he was behind the attacks on cellular phone companies.
His first brush with the law came in 1981, when, as a 17-year-old, he was arrested and charged with stealing computer manuals from Pacific Bell's switching center in Los Angeles. He was prosecuted as a juvenile and sentenced to probation.
A year later, he was caught breaking into computers at the University of Southern California and was jailed for six months.
The exploits of Mr. Mitnick became legendary. For example, after he gained control of the telephone switching network in Los Angeles, he reprogrammed the system to mislead federal agents trying to trace his call. Thinking they had found his hide-out, they barged into the home of a Middle Eastern immigrant watching television.
In 1987, he was arrested and charged with electronically breaking into a computer at the Santa Cruz Operation, a software publisher. He pleaded guilty to a misdemeanor, paid a small fine and was placed on three years' probation.
A year later he was arrested again, this time by FBI agents, and charged with stealing prototype operating system software from Digital. He was later convicted.
Mr. Mitnick vanished in November 1992 after the FBI searched his home with a warrant stating that he was breaking into telephone company computers while working for a Southern California detective agency.