DEFOREST, Wis. -

DeForest police are investigating how copies of teenagers' work permits -- including their Social Security numbers -- vanished from the local high school.

Eleven teenagers applied for work permits through DeForest Area High School, and school administrators kept copies in a locked classroom serving as a temporary office during construction.

Police and a district spokeswoman said there is no strong evidence of how the paperwork disappeared June 28, which frustrated parent Julie Rupp.

"The Social Security numbers, the dates of birth, basically everything needed to steal someone's identity, those should be guarded very carefully," said Rupp, whose son was among the victims.

Rupp has asked the district to reimburse her for nearly $50 spent trying to get her son Aaron's credit frozen.

DeForest administrators are still figuring out how to respond to that request, but they're doing everything they can to help the police investigation, said Debbie Brewster, a district spokeswoman.

The school is an "issuing agent" for work permits, which teenagers under the age of 18 need to work summer jobs, Brewster said.

There are no suspects in the case, although the investigation remains open, DeForest Police Sgt. Bob Berg said.

Surveillance video at the school hasn't been helpful, he said.

Anyone with information should call DeForest police at 608-846-6756.