The whereabouts of discs containing Social Security numbers of 1.3 million Chicago voters are still unknown.

The problem began when a serious fire broke out at the Cook County Administration Building in October 2003. The Chicago Board of Elections was forced to remove information from its mainframe and temporarily store it on compact discs.

The CDs included registration records and other personal data, including Social Security numbers. Later, the information was sent to aldermen and ward committees as part of the so-called "Ward Work" discs, a digital collection of voters' information.

Social Security numbers were not supposed to be included on those discs.

The board has failed to notify the majority of 1.3 million voters that their private information -- including birth dates and addresses -- was placed accidentally on about 100 CDs, board spokesman Jim Allen said.

The board wants to alert voters to the possibility of identity theft, although no such cases have been reported yet, he said Thursday.

Allen said the board has been working with the offices of the Illinois attorney general and the Cook County state's attorney on a plan to notify voters.

The board hasn't retrieved all of the discs yet, Allen said. But, he said, the chances are slim that politicians and political groups kept the CDs because the discs "contained data with a very short shelf life."

Allen said the board now only collects the last four digits of voters' Social Security numbers. It erased the first five digits from the nine-digit number in old voter registration records last October, he said.

Aldermanic candidate Peter Zelchenko discovered the accidental inclusion of Social Security numbers on a disc he received. His attorney, Nick Kefalos, filed a lawsuit against the board late last month, alleging the board violated the Illinois Personal Information Protection Act.

"We're going to get to the bottom of this," Kefalos said. "It appears this was the course of doing business -- handing out information like candy."