RALEIGH, N.C. (AP) _ Federal authorities see him as the world's most wanted computer hacker. But to his former therapist, Kevin Mitnick is just ``a sad, lonely, angry, isolated boy'' who spent more time with computers than people.

Culminating a search that began in November 1992, federal agents arrested Mitnick early Wednesday at his Raleigh apartment.

Mitnick, who once broke into a top-secret military defense system as a teen-age prank, allegedly pilfered thousands of data files and at least 20,000 credit card numbers, worming his way into even the most sophisticated systems.

A detention hearing was scheduled for Friday morning before a federal magistrate.

Mitnick, 31, was charged with computer fraud, punishable by 20 years in prison, and illegal use of a telephone access device, which carries a maximum 15-year sentence. Both crimes also are punishable by $250,000 fines. In addition, he was wanted in California for allegedly violating probation on a previous hacking conviction.

``It was an intensive, two-week-long electronic manhunt that involved several dozen law enforcement agents around the country,'' Assistant U.S. Attorney Kent Walker in San Francisco said Thursday.

But others pooh-poohed the depiction of Mitnick as the cyberthief to beat all cyberthieves.

``That's what I see, a sad, lonely, angry, isolated boy,'' Harriet Rosetto, Mitnick's former therapist, told the Daily News of Los Angeles after learning of his arrest.

``I don't think he's that important a person. I think he's become mythical,'' she said. ``That he's become public enemy No. 1 is kind of laughable.

``I think that had he found a way to be accepted in the mainstream, he would have joined the mainstream,'' Rosetto said. ``He already had this reputation as this Svengali character. Nobody wanted to go near him.''

One of the first indicted under the Computer Security Act of 1987, Mitnick was convicted of getting into MCI telephone computers and accessing long-distance codes, and of causing $4 million damage to Digital Equipment Corp.

The $4 million actually represented computer down-time, not damage, said attorney Alan Rubin who defended Mitnick. But it was Mitnick's third conviction and he served one year in prison.

At the 1989 sentencing, U.S. District Judge Mariana Pfaelzer ruled that Mitnick's hacking was an addiction, like drugs, alcohol or the junk food he lived on. She agreed that he was dangerous when armed with a computer and phone line, and ordered him to get therapy and go to prison.

In therapy, Mitnick lost 100 of his nearly 300 pounds and worked on his self-esteem, Rosetto said.

Tom Perrine, who used to develop software to protect classified information for the federal government, said authorities are behind when it comes to computer hacking investigations.

And in the end, it took someone with the skills of Tsutomu Shimomura, a 30-year-old computer security specialist at the San Diego Supercomputer Center, to help the federal agents track Mitnick.

Shimomura's own computer at his California beach house, which was linked to the system at the center, was hit by a hacker on Christmas Day, said center spokeswoman Stephanie Sides.

Incensed, Shimomura canceled a ski vacation and assembled a team of computer experts to hunt down the intruder. They traced Mitnick to Netcom, a nationwide Internet access provider, and with the help of federally subpoenaed phone records determined that he was placing calls from a cellular phone near Raleigh-Durham International Airport.

Early Monday morning, Shimomura drove around Raleigh with a telephone company technician. They used a cellular frequency direction-finding antenna hooked to a laptop to narrow the search to an apartment complex.

The FBI arrested Mitnick after a 24-hour stakeout.

Shimomura attended Mitnick's prearraignment hearing Wednesday at the federal courthouse in Raleigh. At the end of the hearing, a handcuffed Mitnick turned to Shimomura, whom he had never met, according to The New York Times.

``Hello, Tsutomu,'' Mitnick said. ``I respect your skills.''

Shimomura nodded solemnly.

Mitnick's career has puzzled his mother as much as anyone.

``He's being talked about like he's some whiz kid,'' Shelly Jaffee said in 1988 after the third arrest. ``He's just not that smart. The kid never finished high school.''