Olathe ? Authorities think an Overland Park man is “Artech,” a computer hacker suspected of getting into more then 50 Web sites in 1999 and 2000.

Matthew T. Kroeker, 18, appeared in Johnson County District Court Friday on 11 felony counts of computer crime. He was charged in the juvenile division because he was 16 when the crimes occurred, but prosecutors said they would seek to try him as an adult.

Kroeker is being held under house arrest, with his next court hearing scheduled for March 25.

Kroeker is accused of getting into Web sites run by the U.S. Department of Transportation, U.S. Department of Labor, the National Institutes of Health, the cities of Stockton, Calif., and Overland Park, and the Haysville school district.

Defense lawyer Kevin Moriarty said Kroeker cooperated fully with authorities when they questioned him almost two years ago.

The FBI and detectives from Overland Park and Stockton, Calif., took part in the investigation. Johnson County is prosecuting because federal courts do not handle juvenile cases.

The probe began in January 2000 when an unauthorized message was posted on a Greater Kansas City Chamber of Commerce site. But it was an attack on the Stockton, Calif., Web site in June 2000 that led investigators to Kroeker.

After the city’s site was invaded, employees received e-mails from Artech, who offered to help the city protect itself from such attacks in exchange for a laptop computer, according to the allegations. Artech allegedly made similar offers to other victims.