Police say a student using a school computer last month was able to access personal information about every student enrolled at Joliet West High School.
The student allegedly downloaded a list of names and Social Security numbers to his iPod on March 7, according to reports.
Police Chief Fred Hayes said the school learned George C. Janecek, 18, had gotten the information after he showed it to other students who notified a teacher that day.
"Apparently, Janecek, who is in the school's ROTC program, has authorized access to a computer at the school to work on the ROTC Web site," said Hayes. "But he does not have authorized access to student data."
The school conducted an internal investigation which concluded March 13 when they notified Joliet police of the breach.
"We conducted an investigation that day and arrested Janecek on a misdemeanor charge of computer tampering," Hayes said.
Police seized the computer and iPod he reportedly used.
"Our investigation determined none of the data was used or disseminated," Hayes said.
School district spokeswoman Kristine Schlismann said the issue is a police matter.
"Investigators have assured us that there is no reason to believe that any accessed information was communicated to third parties," she said. "In compliance with the Illinois Personal Information Protection Act, a letter will be sent to any person whose personal information may have been obtained."